Core Internals — SQLAlchemy 1.4 Documentation

Release: 1.4.51 | Release Date: January 2, 2024

# SQLAlchemy 1.4 Documentation

# Core Internals

Some key internal constructs are listed here.

Object Name | Description
--- | ---
AdaptedConnection | Interface of an adapted connection object to support the DBAPI protocol.
Compiled | Represent a compiled SQL or DDL expression.
DDLCompiler |
DefaultDialect | Default implementation of Dialect
DefaultExecutionContext |
Dialect | Define the behavior of a specific database and DB-API combination.
ExecutionContext | A messenger object for a Dialect that corresponds to a single execution.
GenericTypeCompiler |
Identified |
IdentifierPreparer | Handle quoting and case-folding of identifiers based on options.
SQLCompiler | Default implementation of `Compiled`.
StrSQLCompiler | A `SQLCompiler` subclass which allows a small selection of non-standard SQL features to render into a string value.

class sqlalchemy.engine.Compiled(dialect, statement, schema_translate_map=None, render_schema_translate=False, compile_kwargs={})

  Represent a compiled SQL or DDL expression.

  Members

  __init__(), compile_state, construct_params(), dml_compile_state, execution_options, params, sql_compiler

  The `__str__` method of the `Compiled` object should produce the actual text of the statement. `Compiled` objects are specific to their underlying database dialect, and also may or may not be specific to the columns referenced within a particular set of bind parameters. In no case should the `Compiled` object be dependent on the actual values of those bind parameters, even though it may reference those values as defaults.

  method `sqlalchemy.engine.Compiled.` __init__(dialect, statement, schema_translate_map=None, render_schema_translate=False, compile_kwargs={})

    Construct a new `Compiled` object.

    Parameters:

      - dialect – `Dialect` to compile against.

      - statement – `ClauseElement` to be compiled.

      - schema_translate_map –

        dictionary of schema names to be translated when forming the resultant SQL

        New in version 1.1.

        See also

        Translation of Schema Names

      - compile_kwargs – additional kwargs that will be passed to the initial call to `Compiled.process()`.

  attribute `sqlalchemy.engine.Compiled.` compile_state = None

    Optional `CompileState` object that maintains additional state used by the compiler.

    Major executable objects such as `Insert`, `Update`, `Delete`, `Select` will generate this state when compiled in order to calculate additional information about the object. For the top level object that is to be executed, the state can be stored here where it can also have applicability towards result set processing.

    New in version 1.4.

  method `sqlalchemy.engine.Compiled.` construct_params(params=None, extracted_parameters=None, escape_names=True)

    Return the bind params for this compiled object.

    Parameters:

      params – a dict of string/object pairs whose values will override bind values compiled in to the statement.

  attribute `sqlalchemy.engine.Compiled.` dml_compile_state = None

    Optional `CompileState` assigned at the same point that .isinsert, .isupdate, or .isdelete is assigned.

    This will normally be the same object as .compile_state, with the exception of cases like the `ORMFromStatementCompileState` object.

    New in version 1.4.40.

  attribute `sqlalchemy.engine.Compiled.` execution_options = {}

    Execution options propagated from the statement. In some cases, sub-elements of the statement can modify these.

  attribute `sqlalchemy.engine.Compiled.` params

    Return the bind params for this compiled object.

  attribute `sqlalchemy.engine.Compiled.` sql_compiler

    Return a Compiled that is capable of processing SQL expressions.

    If this compiler is one, it would likely just return ‘self’.

class sqlalchemy.sql.compiler.DDLCompiler(dialect, statement, schema_translate_map=None, render_schema_translate=False, compile_kwargs={})

  Members

  __init__(), compile_state, construct_params(), define_constraint_remote_table(), dml_compile_state, execution_options, params, sql_compiler

  Class signature

  class `sqlalchemy.sql.compiler.DDLCompiler` (`sqlalchemy.sql.compiler.Compiled`)

  method `sqlalchemy.sql.compiler.DDLCompiler.` __init__(dialect, statement, schema_translate_map=None, render_schema_translate=False, compile_kwargs={})

    inherited from the `sqlalchemy.sql.compiler.Compiled.__init__` method of `Compiled`

    Construct a new `Compiled` object.

    Parameters:

      - dialect – `Dialect` to compile against.

      - statement – `ClauseElement` to be compiled.

      - schema_translate_map –

        dictionary of schema names to be translated when forming the resultant SQL

        New in version 1.1.

        See also

        Translation of Schema Names

      - compile_kwargs – additional kwargs that will be passed to the initial call to `Compiled.process()`.

  attribute `sqlalchemy.sql.compiler.DDLCompiler.` compile_state = None

    inherited from the `Compiled.compile_state` attribute of `Compiled`

    Optional `CompileState` object that maintains additional state used by the compiler.

    Major executable objects such as `Insert`, `Update`, `Delete`, `Select` will generate this state when compiled in order to calculate additional information about the object. For the top level object that is to be executed, the state can be stored here where it can also have applicability towards result set processing.

    New in version 1.4.

  method `sqlalchemy.sql.compiler.DDLCompiler.` construct_params(params=None, extracted_parameters=None, escape_names=True)

    Return the bind params for this compiled object.

    Parameters:

      params – a dict of string/object pairs whose values will override bind values compiled in to the statement.

  method `sqlalchemy.sql.compiler.DDLCompiler.` define_constraint_remote_table(constraint, table, preparer)

    Format the remote table clause of a CREATE CONSTRAINT clause.

  attribute `sqlalchemy.sql.compiler.DDLCompiler.` dml_compile_state = None

    inherited from the `Compiled.dml_compile_state` attribute of `Compiled`

    Optional `CompileState` assigned at the same point that .isinsert, .isupdate, or .isdelete is assigned.

    This will normally be the same object as .compile_state, with the exception of cases like the `ORMFromStatementCompileState` object.

    New in version 1.4.40.

  attribute `sqlalchemy.sql.compiler.DDLCompiler.` execution_options = {}

    inherited from the `Compiled.execution_options` attribute of `Compiled`

    Execution options propagated from the statement. In some cases, sub-elements of the statement can modify these.

  attribute `sqlalchemy.sql.compiler.DDLCompiler.` params

    inherited from the `Compiled.params` attribute of `Compiled`

    Return the bind params for this compiled object.

  attribute `sqlalchemy.sql.compiler.DDLCompiler.` sql_compiler

class sqlalchemy.engine.default.DefaultDialect(convert_unicode=False, encoding='utf-8', paramstyle=None, dbapi=None, implicit_returning=None, case_sensitive=True, supports_native_boolean=None, max_identifier_length=None, label_length=None, compiler_linting=0, server_side_cursors=False, **kwargs)

  Default implementation of Dialect

  Members

  connect(), construct_arguments, create_connect_args(), create_xid(), dbapi_exception_translation_map, ddl_compiler, denormalize_name(), do_begin(), do_begin_twophase(), do_close(), do_commit(), do_commit_twophase(), do_execute(), do_execute_no_params(), do_executemany(), do_prepare_twophase(), do_recover_twophase(), do_release_savepoint(), do_rollback(), do_rollback_to_savepoint(), do_rollback_twophase(), do_savepoint(), do_set_input_sizes(), do_terminate(), engine_created(), execute_sequence_format, execution_ctx_cls, get_check_constraints(), get_columns(), get_default_isolation_level(), get_dialect_cls(), get_driver_connection(), get_foreign_keys(), get_indexes(), get_isolation_level(), get_pk_constraint(), get_sequence_names(), get_table_comment(), get_table_names(), get_temp_table_names(), get_temp_view_names(), get_unique_constraints(), get_view_definition(), get_view_names(), has_index(), has_sequence(), has_table(), initialize(), is_disconnect(), load_provisioning(), normalize_name(), on_connect(), on_connect_url(), preparer, reset_isolation_level(), returns_unicode_strings, set_isolation_level(), statement_compiler, supports_default_metavalue, supports_default_values, supports_empty_insert, supports_sane_rowcount_returning, supports_statement_cache, type_compiler, type_descriptor()

  Class signature

  class `sqlalchemy.engine.default.DefaultDialect` (`sqlalchemy.engine.interfaces.Dialect`)

  method `sqlalchemy.engine.default.DefaultDialect.` connect(*cargs, **cparams)

    Establish a connection using this dialect’s DBAPI.

    The default implementation of this method is:

        def connect(self, *cargs, **cparams):
            return self.dbapi.connect(*cargs, **cparams)

    The `*cargs, **cparams` parameters are generated directly from this dialect’s `Dialect.create_connect_args()` method.

    This method may be used for dialects that need to perform programmatic per-connection steps when a new connection is procured from the DBAPI.

    Parameters:

      - *cargs – positional parameters returned from the `Dialect.create_connect_args()` method

      - **cparams – keyword parameters returned from the `Dialect.create_connect_args()` method.

    Returns:

      a DBAPI connection, typically from the PEP 249 module level `.connect()` function.

    See also

    `Dialect.create_connect_args()`

    `Dialect.on_connect()`

  attribute `sqlalchemy.engine.default.DefaultDialect.` construct_arguments = None

    Optional set of argument specifiers for various SQLAlchemy constructs, typically schema items.

    To implement, establish as a series of tuples, as in:

        construct_arguments = [
            (schema.Index, {
                "using": False,
                "where": None,
                "ops": None
            })
        ]

    If the above construct is established on the PostgreSQL dialect, the `Index` construct will now accept the keyword arguments `postgresql_using`, `postgresql_where`, nad `postgresql_ops`. Any other argument specified to the constructor of `Index` which is prefixed with `postgresql_` will raise `ArgumentError`.

    A dialect which does not include a `construct_arguments` member will not participate in the argument validation system. For such a dialect, any argument name is accepted by all participating constructs, within the namespace of arguments prefixed with that dialect name. The rationale here is so that third-party dialects that haven’t yet implemented this feature continue to function in the old way.

    New in version 0.9.2.

    See also

    `DialectKWArgs` - implementing base class which consumes `DefaultDialect.construct_arguments`

  method `sqlalchemy.engine.default.DefaultDialect.` create_connect_args(url)

    Build DB-API compatible connection arguments.

    Given a `URL` object, returns a tuple consisting of a `(*args, **kwargs)` suitable to send directly to the dbapi’s connect function. The arguments are sent to the `Dialect.connect()` method which then runs the DBAPI-level `connect()` function.

    The method typically makes use of the `URL.translate_connect_args()` method in order to generate a dictionary of options.

    The default implementation is:

        def create_connect_args(self, url):
            opts = url.translate_connect_args()
            opts.update(url.query)
            return [[], opts]

    Parameters:

      url – a `URL` object

    Returns:

      a tuple of `(*args, **kwargs)` which will be passed to the `Dialect.connect()` method.

    See also

    `URL.translate_connect_args()`

  method `sqlalchemy.engine.default.DefaultDialect.` create_xid()

    Create a random two-phase transaction ID.

    This id will be passed to do_begin_twophase(), do_rollback_twophase(), do_commit_twophase(). Its format is unspecified.

  attribute `sqlalchemy.engine.default.DefaultDialect.` dbapi_exception_translation_map = {}

    mapping used in the extremely unusual case that a DBAPI’s published exceptions don’t actually have the __name__ that they are linked towards.

    New in version 1.0.5.

  attribute `sqlalchemy.engine.default.DefaultDialect.` ddl_compiler

    alias of `DDLCompiler`

  method `sqlalchemy.engine.default.DefaultDialect.` denormalize_name(name)

    convert the given name to a case insensitive identifier for the backend if it is an all-lowercase name.

    This method is only used if the dialect defines requires_name_normalize=True.

  method `sqlalchemy.engine.default.DefaultDialect.` do_begin(dbapi_connection)

    Provide an implementation of `connection.begin()`, given a DB-API connection.

    The DBAPI has no dedicated “begin” method and it is expected that transactions are implicit. This hook is provided for those DBAPIs that might need additional help in this area.

    Note that `Dialect.do_begin()` is not called unless a `Transaction` object is in use. The `Dialect.do_autocommit()` hook is provided for DBAPIs that need some extra commands emitted after a commit in order to enter the next transaction, when the SQLAlchemy `Connection` is used in its default “autocommit” mode.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_begin_twophase(connection, xid)

    inherited from the `Dialect.do_begin_twophase()` method of `Dialect`

    Begin a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

  method `sqlalchemy.engine.default.DefaultDialect.` do_close(dbapi_connection)

    Provide an implementation of `connection.close()`, given a DBAPI connection.

    This hook is called by the `Pool` when a connection has been detached from the pool, or is being returned beyond the normal capacity of the pool.

  method `sqlalchemy.engine.default.DefaultDialect.` do_commit(dbapi_connection)

    Provide an implementation of `connection.commit()`, given a DB-API connection.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_commit_twophase(connection, xid, is_prepared=True, recover=False)

    inherited from the `Dialect.do_commit_twophase()` method of `Dialect`

    Commit a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

      - is_prepared – whether or not `TwoPhaseTransaction.prepare()` was called.

      - recover – if the recover flag was passed.

  method `sqlalchemy.engine.default.DefaultDialect.` do_execute(cursor, statement, parameters, context=None)

    Provide an implementation of `cursor.execute(statement, parameters)`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_execute_no_params(cursor, statement, context=None)

    Provide an implementation of `cursor.execute(statement)`.

    The parameter collection should not be sent.

  method `sqlalchemy.engine.default.DefaultDialect.` do_executemany(cursor, statement, parameters, context=None)

    Provide an implementation of `cursor.executemany(statement, parameters)`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_prepare_twophase(connection, xid)

    inherited from the `Dialect.do_prepare_twophase()` method of `Dialect`

    Prepare a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

  method `sqlalchemy.engine.default.DefaultDialect.` do_recover_twophase(connection)

    inherited from the `Dialect.do_recover_twophase()` method of `Dialect`

    Recover list of uncommitted prepared two phase transaction identifiers on the given connection.

    Parameters:

      connection – a `Connection`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_release_savepoint(connection, name)

    Release the named savepoint on a connection.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.default.DefaultDialect.` do_rollback(dbapi_connection)

    Provide an implementation of `connection.rollback()`, given a DB-API connection.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.default.DefaultDialect.` do_rollback_to_savepoint(connection, name)

    Rollback a connection to the named savepoint.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.default.DefaultDialect.` do_rollback_twophase(connection, xid, is_prepared=True, recover=False)

    inherited from the `Dialect.do_rollback_twophase()` method of `Dialect`

    Rollback a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

      - is_prepared – whether or not `TwoPhaseTransaction.prepare()` was called.

      - recover – if the recover flag was passed.

  method `sqlalchemy.engine.default.DefaultDialect.` do_savepoint(connection, name)

    Create a savepoint with the given name.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.default.DefaultDialect.` do_set_input_sizes(cursor, list_of_tuples, context)

    inherited from the `Dialect.do_set_input_sizes()` method of `Dialect`

    invoke the cursor.setinputsizes() method with appropriate arguments

    This hook is called if the dialect.use_inputsizes flag is set to True. Parameter data is passed in a list of tuples (paramname, dbtype, sqltype), where `paramname` is the key of the parameter in the statement, `dbtype` is the DBAPI datatype and `sqltype` is the SQLAlchemy type. The order of tuples is in the correct parameter order.

    New in version 1.4.

  method `sqlalchemy.engine.default.DefaultDialect.` do_terminate(dbapi_connection)

    Provide an implementation of `connection.close()` that tries as much as possible to not block, given a DBAPI connection.

    In the vast majority of cases this just calls .close(), however for some asyncio dialects may call upon different API features.

    This hook is called by the `Pool` when a connection is being recycled or has been invalidated.

    New in version 1.4.41.

  classmethod `sqlalchemy.engine.default.DefaultDialect.` engine_created(engine)

    inherited from the `Dialect.engine_created()` method of `Dialect`

    A convenience hook called before returning the final `Engine`.

    If the dialect returned a different class from the `get_dialect_cls()` method, then the hook is called on both classes, first on the dialect class returned by the `get_dialect_cls()` method and then on the class on which the method was called.

    The hook should be used by dialects and/or wrappers to apply special events to the engine or its components. In particular, it allows a dialect-wrapping class to apply dialect-level events.

    New in version 1.0.3.

  attribute `sqlalchemy.engine.default.DefaultDialect.` execute_sequence_format

    alias of `tuple`

  attribute `sqlalchemy.engine.default.DefaultDialect.` execution_ctx_cls

    alias of `DefaultExecutionContext`

  method `sqlalchemy.engine.default.DefaultDialect.` get_check_constraints(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_check_constraints()` method of `Dialect`

    Return information about check constraints in table_name.

    Given a string table_name and an optional string schema, return check constraint information as a list of dicts with these keys:

    - `name` - the check constraint’s name

    - `sqltext` - the check constraint’s SQL expression

    - `**kw` - other options passed to the dialect’s get_check_constraints() method.

    New in version 1.1.0.

  method `sqlalchemy.engine.default.DefaultDialect.` get_columns(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_columns()` method of `Dialect`

    Return information about columns in table_name.

    Given a `Connection`, a string table_name, and an optional string schema, return column information as a list of dictionaries with these keys:

    name

      the column’s name

    type

      [sqlalchemy.types#TypeEngine]

    nullable

      boolean

    default

      the column’s default value

    autoincrement

      boolean

    sequence
      a dictionary of the form
        {‘name’str, ‘start’ :int, ‘increment’: int, ‘minvalue’: int,

          ‘maxvalue’: int, ‘nominvalue’: bool, ‘nomaxvalue’: bool, ‘cycle’: bool, ‘cache’: int, ‘order’: bool}

    Additional column attributes may be present.

  method `sqlalchemy.engine.default.DefaultDialect.` get_default_isolation_level(dbapi_conn)

    Given a DBAPI connection, return its isolation level, or a default isolation level if one cannot be retrieved.

    May be overridden by subclasses in order to provide a “fallback” isolation level for databases that cannot reliably retrieve the actual isolation level.

    By default, calls the `Interfaces.get_isolation_level()` method, propagating any exceptions raised.

    New in version 1.3.22.

  classmethod `sqlalchemy.engine.default.DefaultDialect.` get_dialect_cls(url)

    inherited from the `Dialect.get_dialect_cls()` method of `Dialect`

    Given a URL, return the `Dialect` that will be used.

    This is a hook that allows an external plugin to provide functionality around an existing dialect, by allowing the plugin to be loaded from the url based on an entrypoint, and then the plugin returns the actual dialect to be used.

    By default this just returns the cls.

    New in version 1.0.3.

  method `sqlalchemy.engine.default.DefaultDialect.` get_driver_connection(connection)

    Returns the connection object as returned by the external driver package.

    For normal dialects that use a DBAPI compliant driver this call will just return the `connection` passed as argument. For dialects that instead adapt a non DBAPI compliant driver, like when adapting an asyncio driver, this call will return the connection-like object as returned by the driver.

    New in version 1.4.24.

  method `sqlalchemy.engine.default.DefaultDialect.` get_foreign_keys(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_foreign_keys()` method of `Dialect`

    Return information about foreign_keys in table_name.

    Given a `Connection`, a string table_name, and an optional string schema, return foreign key information as a list of dicts with these keys:

    name

      the constraint’s name

    constrained_columns

      a list of column names that make up the foreign key

    referred_schema

      the name of the referred schema

    referred_table

      the name of the referred table

    referred_columns

      a list of column names in the referred table that correspond to constrained_columns

  method `sqlalchemy.engine.default.DefaultDialect.` get_indexes(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_indexes()` method of `Dialect`

    Return information about indexes in table_name.

    Given a `Connection`, a string table_name and an optional string schema, return index information as a list of dictionaries with these keys:

    name

      the index’s name

    column_names

      list of column names in order

    unique

      boolean

  method `sqlalchemy.engine.default.DefaultDialect.` get_isolation_level(dbapi_conn)

    inherited from the `Dialect.get_isolation_level()` method of `Dialect`

    Given a DBAPI connection, return its isolation level.

    When working with a `Connection` object, the corresponding DBAPI connection may be procured using the `Connection.connection` accessor.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  method `sqlalchemy.engine.default.DefaultDialect.` get_pk_constraint(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_pk_constraint()` method of `Dialect`

    Return information about the primary key constraint on table_name`.

    Given a `Connection`, a string table_name, and an optional string schema, return primary key information as a dictionary with these keys:

    constrained_columns

      a list of column names that make up the primary key

    name

      optional name of the primary key constraint.

  method `sqlalchemy.engine.default.DefaultDialect.` get_sequence_names(connection, schema=None, **kw)

    inherited from the `Dialect.get_sequence_names()` method of `Dialect`

    Return a list of all sequence names available in the database.

    Parameters:

      schema – schema name to query, if not the default schema.

    New in version 1.4.

  method `sqlalchemy.engine.default.DefaultDialect.` get_table_comment(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_table_comment()` method of `Dialect`

    Return the “comment” for the table identified by table_name.

    Given a string table_name and an optional string schema, return table comment information as a dictionary with this key:

    text

      text of the comment

    Raises `NotImplementedError` for dialects that don’t support comments.

    New in version 1.2.

  method `sqlalchemy.engine.default.DefaultDialect.` get_table_names(connection, schema=None, **kw)

    inherited from the `Dialect.get_table_names()` method of `Dialect`

    Return a list of table names for schema.

  method `sqlalchemy.engine.default.DefaultDialect.` get_temp_table_names(connection, schema=None, **kw)

    inherited from the `Dialect.get_temp_table_names()` method of `Dialect`

    Return a list of temporary table names on the given connection, if supported by the underlying backend.

  method `sqlalchemy.engine.default.DefaultDialect.` get_temp_view_names(connection, schema=None, **kw)

    inherited from the `Dialect.get_temp_view_names()` method of `Dialect`

    Return a list of temporary view names on the given connection, if supported by the underlying backend.

  method `sqlalchemy.engine.default.DefaultDialect.` get_unique_constraints(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.get_unique_constraints()` method of `Dialect`

    Return information about unique constraints in table_name.

    Given a string table_name and an optional string schema, return unique constraint information as a list of dicts with these keys:

    name

      the unique constraint’s name

    column_names

      list of column names in order

    **kw

      other options passed to the dialect’s get_unique_constraints() method.

    New in version 0.9.0.

  method `sqlalchemy.engine.default.DefaultDialect.` get_view_definition(connection, view_name, schema=None, **kw)

    inherited from the `Dialect.get_view_definition()` method of `Dialect`

    Return view definition.

    Given a `Connection`, a string view_name, and an optional string schema, return the view definition.

  method `sqlalchemy.engine.default.DefaultDialect.` get_view_names(connection, schema=None, **kw)

    inherited from the `Dialect.get_view_names()` method of `Dialect`

    Return a list of all view names available in the database.

    Parameters:

      schema – schema name to query, if not the default schema.

  method `sqlalchemy.engine.default.DefaultDialect.` has_index(connection, table_name, index_name, schema=None)

    Check the existence of a particular index name in the database.

    Given a `Connection` object, a string table_name and string index name, return True if an index of the given name on the given table exists, false otherwise.

    The `DefaultDialect` implements this in terms of the `Dialect.has_table()` and `Dialect.get_indexes()` methods, however dialects can implement a more performant version.

    New in version 1.4.

  method `sqlalchemy.engine.default.DefaultDialect.` has_sequence(connection, sequence_name, schema=None, **kw)

    inherited from the `Dialect.has_sequence()` method of `Dialect`

    Check the existence of a particular sequence in the database.

    Given a `Connection` object and a string sequence_name, return True if the given sequence exists in the database, False otherwise.

  method `sqlalchemy.engine.default.DefaultDialect.` has_table(connection, table_name, schema=None, **kw)

    inherited from the `Dialect.has_table()` method of `Dialect`

    For internal dialect use, check the existence of a particular table in the database.

    Given a `Connection` object, a string table_name and optional schema name, return True if the given table exists in the database, False otherwise.

    This method serves as the underlying implementation of the public facing `Inspector.has_table()` method, and is also used internally to implement the “checkfirst” behavior for methods like `Table.create()` and `MetaData.create_all()`.

    Note

    This method is used internally by SQLAlchemy, and is published so that third-party dialects may provide an implementation. It is not the public API for checking for table presence. Please use the `Inspector.has_table()` method. Alternatively, for legacy cross-compatibility, the `Engine.has_table()` method may be used.

  method `sqlalchemy.engine.default.DefaultDialect.` initialize(connection)

    Called during strategized creation of the dialect with a connection.

    Allows dialects to configure options based on server version info or other properties.

    The connection passed here is a SQLAlchemy Connection object, with full capabilities.

    The initialize() method of the base dialect should be called via super().

    Note

    as of SQLAlchemy 1.4, this method is called before any `Dialect.on_connect()` hooks are called.

  method `sqlalchemy.engine.default.DefaultDialect.` is_disconnect(e, connection, cursor)

    Return True if the given DB-API error indicates an invalid connection

  classmethod `sqlalchemy.engine.default.DefaultDialect.` load_provisioning()

    set up the provision.py module for this dialect.

    For dialects that include a provision.py module that sets up provisioning followers, this method should initiate that process.

    A typical implementation would be:

        @classmethod
        def load_provisioning(cls):
            __import__("mydialect.provision")

    The default method assumes a module named `provision.py` inside the owning package of the current dialect, based on the `__module__` attribute:

        @classmethod
        def load_provisioning(cls):
            package = ".".join(cls.__module__.split(".")[0:-1])
            try:
                __import__(package + ".provision")
            except ImportError:
                pass

    New in version 1.3.14.

  method `sqlalchemy.engine.default.DefaultDialect.` normalize_name(name)

    convert the given name to lowercase if it is detected as case insensitive.

    This method is only used if the dialect defines requires_name_normalize=True.

  method `sqlalchemy.engine.default.DefaultDialect.` on_connect()

    return a callable which sets up a newly created DBAPI connection.

    The callable should accept a single argument “conn” which is the DBAPI connection itself. The inner callable has no return value.

    E.g.:

        class MyDialect(default.DefaultDialect):
            # ...

            def on_connect(self):
                def do_on_connect(connection):
                    connection.execute("SET SPECIAL FLAGS etc")

                return do_on_connect

    This is used to set dialect-wide per-connection options such as isolation modes, Unicode modes, etc.

    The “do_on_connect” callable is invoked by using the `PoolEvents.connect()` event hook, then unwrapping the DBAPI connection and passing it into the callable.

    Changed in version 1.4: the on_connect hook is no longer called twice for the first connection of a dialect. The on_connect hook is still called before the `Dialect.initialize()` method however.

    Changed in version 1.4.3: the on_connect hook is invoked from a new method on_connect_url that passes the URL that was used to create the connect args. Dialects can implement on_connect_url instead of on_connect if they need the URL object that was used for the connection in order to get additional context.

    If None is returned, no event listener is generated.

    Returns:

      a callable that accepts a single DBAPI connection as an argument, or None.

    See also

    `Dialect.connect()` - allows the DBAPI `connect()` sequence itself to be controlled.

    `Dialect.on_connect_url()` - supersedes `Dialect.on_connect()` to also receive the `URL` object in context.

  method `sqlalchemy.engine.default.DefaultDialect.` on_connect_url(url)

    inherited from the `Dialect.on_connect_url()` method of `Dialect`

    return a callable which sets up a newly created DBAPI connection.

    This method is a new hook that supersedes the `Dialect.on_connect()` method when implemented by a dialect. When not implemented by a dialect, it invokes the `Dialect.on_connect()` method directly to maintain compatibility with existing dialects. There is no deprecation for `Dialect.on_connect()` expected.

    The callable should accept a single argument “conn” which is the DBAPI connection itself. The inner callable has no return value.

    E.g.:

        class MyDialect(default.DefaultDialect):
            # ...

            def on_connect_url(self, url):
                def do_on_connect(connection):
                    connection.execute("SET SPECIAL FLAGS etc")

                return do_on_connect

    This is used to set dialect-wide per-connection options such as isolation modes, Unicode modes, etc.

    This method differs from `Dialect.on_connect()` in that it is passed the `URL` object that’s relevant to the connect args. Normally the only way to get this is from the `Dialect.on_connect()` hook is to look on the `Engine` itself, however this URL object may have been replaced by plugins.

    Note

    The default implementation of `Dialect.on_connect_url()` is to invoke the `Dialect.on_connect()` method. Therefore if a dialect implements this method, the `Dialect.on_connect()` method will not be called unless the overriding dialect calls it directly from here.

    New in version 1.4.3: added `Dialect.on_connect_url()` which normally calls into `Dialect.on_connect()`.

    Parameters:

      url – a `URL` object representing the `URL` that was passed to the `Dialect.create_connect_args()` method.

    Returns:

      a callable that accepts a single DBAPI connection as an argument, or None.

    See also

    `Dialect.on_connect()`

  attribute `sqlalchemy.engine.default.DefaultDialect.` preparer

    alias of `IdentifierPreparer`

  method `sqlalchemy.engine.default.DefaultDialect.` reset_isolation_level(dbapi_conn)

    Given a DBAPI connection, revert its isolation to the default.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  attribute `sqlalchemy.engine.default.DefaultDialect.` returns_unicode_strings = symbol('RETURNS_UNICODE')
  method `sqlalchemy.engine.default.DefaultDialect.` set_isolation_level(dbapi_conn, level)

    inherited from the `Dialect.set_isolation_level()` method of `Dialect`

    Given a DBAPI connection, set its isolation level.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  attribute `sqlalchemy.engine.default.DefaultDialect.` statement_compiler

    alias of `SQLCompiler`

  attribute `sqlalchemy.engine.default.DefaultDialect.` supports_default_metavalue = False

    dialect supports INSERT… VALUES (DEFAULT) syntax

  attribute `sqlalchemy.engine.default.DefaultDialect.` supports_default_values = False

    dialect supports INSERT… DEFAULT VALUES syntax

  attribute `sqlalchemy.engine.default.DefaultDialect.` supports_empty_insert = True

    dialect supports INSERT () VALUES ()

  attribute `sqlalchemy.engine.default.DefaultDialect.` supports_sane_rowcount_returning

    True if this dialect supports sane rowcount even if RETURNING is in use.

    For dialects that don’t support RETURNING, this is synonymous with `supports_sane_rowcount`.

  attribute `sqlalchemy.engine.default.DefaultDialect.` supports_statement_cache = True

    indicates if this dialect supports caching.

    All dialects that are compatible with statement caching should set this flag to True directly on each dialect class and subclass that supports it. SQLAlchemy tests that this flag is locally present on each dialect subclass before it will use statement caching. This is to provide safety for legacy or new dialects that are not yet fully tested to be compliant with SQL statement caching.

    New in version 1.4.5.

    See also

    Caching for Third Party Dialects

  attribute `sqlalchemy.engine.default.DefaultDialect.` type_compiler

    alias of `GenericTypeCompiler`

  method `sqlalchemy.engine.default.DefaultDialect.` type_descriptor(typeobj)

    Provide a database-specific `TypeEngine` object, given the generic object which comes from the types module.

    This method looks for a dictionary called `colspecs` as a class or instance-level variable, and passes on to `adapt_type()`.

class sqlalchemy.engine.Dialect

  Define the behavior of a specific database and DB-API combination.

  Any aspect of metadata definition, SQL query generation, execution, result-set handling, or anything else which varies between databases is defined under the general category of the Dialect. The Dialect acts as a factory for other database-specific object implementations including ExecutionContext, Compiled, DefaultGenerator, and TypeEngine.

  Note

  Third party dialects should not subclass `Dialect` directly. Instead, subclass `DefaultDialect` or descendant class.

  All dialects include the following attributes. There are many other attributes that may be supported as well:

  Members

  connect(), create_connect_args(), create_xid(), denormalize_name(), do_begin(), do_begin_twophase(), do_close(), do_commit(), do_commit_twophase(), do_execute(), do_execute_no_params(), do_executemany(), do_prepare_twophase(), do_recover_twophase(), do_release_savepoint(), do_rollback(), do_rollback_to_savepoint(), do_rollback_twophase(), do_savepoint(), do_set_input_sizes(), do_terminate(), engine_created(), get_check_constraints(), get_columns(), get_default_isolation_level(), get_dialect_cls(), get_driver_connection(), get_foreign_keys(), get_indexes(), get_isolation_level(), get_pk_constraint(), get_sequence_names(), get_table_comment(), get_table_names(), get_temp_table_names(), get_temp_view_names(), get_unique_constraints(), get_view_definition(), get_view_names(), has_index(), has_sequence(), has_table(), initialize(), is_disconnect(), load_provisioning(), normalize_name(), on_connect(), on_connect_url(), reset_isolation_level(), set_isolation_level(), supports_statement_cache, type_descriptor()

  `name`

    identifying name for the dialect from a DBAPI-neutral point of view (i.e. ‘sqlite’)

  `driver`

    identifying name for the dialect’s DBAPI

  `positional`

    True if the paramstyle for this Dialect is positional.

  `paramstyle`

    the paramstyle to be used (some DB-APIs support multiple paramstyles).

  `encoding`

    type of encoding to use for unicode, usually defaults to ‘utf-8’.

  `statement_compiler`

    a `Compiled` class used to compile SQL statements

  `ddl_compiler`

    a `Compiled` class used to compile DDL statements

  `server_version_info`

    a tuple containing a version number for the DB backend in use. This value is only available for supporting dialects, and is typically populated during the initial connection to the database.

  `default_schema_name`

    the name of the default schema. This value is only available for supporting dialects, and is typically populated during the initial connection to the database.

  `execution_ctx_cls`

    a `ExecutionContext` class used to handle statement execution

  `execute_sequence_format`

    either the ‘tuple’ or ‘list’ type, depending on what cursor.execute() accepts for the second argument (they vary).

  `preparer`

    a `IdentifierPreparer` class used to quote identifiers.

  `supports_alter`

    `True` if the database supports `ALTER TABLE` - used only for generating foreign key constraints in certain circumstances

  `max_identifier_length`

    The maximum length of identifier names.

  `supports_sane_rowcount`

    Indicate whether the dialect properly implements rowcount for `UPDATE` and `DELETE` statements.

  `supports_sane_multi_rowcount`

    Indicate whether the dialect properly implements rowcount for `UPDATE` and `DELETE` statements when executed via executemany.

  `preexecute_autoincrement_sequences`

    True if ‘implicit’ primary key functions must be executed separately in order to get their value. This is currently oriented towards PostgreSQL.

  `implicit_returning`

    use RETURNING or equivalent during INSERT execution in order to load newly generated primary keys and other column defaults in one execution, which are then available via inserted_primary_key. If an insert statement has returning() specified explicitly, the “implicit” functionality is not used and inserted_primary_key will not be available.

  `colspecs`

    A dictionary of TypeEngine classes from sqlalchemy.types mapped to subclasses that are specific to the dialect class. This dictionary is class-level only and is not accessed from the dialect instance itself.

  `supports_default_values`

    Indicates if the construct `INSERT INTO tablename DEFAULT VALUES` is supported

  `supports_sequences`

    Indicates if the dialect supports CREATE SEQUENCE or similar.

  `sequences_optional`

    If True, indicates if the “optional” flag on the Sequence() construct should signal to not generate a CREATE SEQUENCE. Applies only to dialects that support sequences. Currently used only to allow PostgreSQL SERIAL to be used on a column that specifies Sequence() for usage on other backends.

  `supports_native_enum`

    Indicates if the dialect supports a native ENUM construct. This will prevent types.Enum from generating a CHECK constraint when that type is used.

  `supports_native_boolean`

    Indicates if the dialect supports a native boolean construct. This will prevent types.Boolean from generating a CHECK constraint when that type is used.

  `dbapi_exception_translation_map`

    A dictionary of names that will contain as values the names of pep-249 exceptions (“IntegrityError”, “OperationalError”, etc) keyed to alternate class names, to support the case where a DBAPI has exception classes that aren’t named as they are referred to (e.g. IntegrityError = MyException). In the vast majority of cases this dictionary is empty.

    New in version 1.0.5.

  method `sqlalchemy.engine.Dialect.` connect(*cargs, **cparams)

    Establish a connection using this dialect’s DBAPI.

    The default implementation of this method is:

        def connect(self, *cargs, **cparams):
            return self.dbapi.connect(*cargs, **cparams)

    The `*cargs, **cparams` parameters are generated directly from this dialect’s `Dialect.create_connect_args()` method.

    This method may be used for dialects that need to perform programmatic per-connection steps when a new connection is procured from the DBAPI.

    Parameters:

      - *cargs – positional parameters returned from the `Dialect.create_connect_args()` method

      - **cparams – keyword parameters returned from the `Dialect.create_connect_args()` method.

    Returns:

      a DBAPI connection, typically from the PEP 249 module level `.connect()` function.

    See also

    `Dialect.create_connect_args()`

    `Dialect.on_connect()`

  method `sqlalchemy.engine.Dialect.` create_connect_args(url)

    Build DB-API compatible connection arguments.

    Given a `URL` object, returns a tuple consisting of a `(*args, **kwargs)` suitable to send directly to the dbapi’s connect function. The arguments are sent to the `Dialect.connect()` method which then runs the DBAPI-level `connect()` function.

    The method typically makes use of the `URL.translate_connect_args()` method in order to generate a dictionary of options.

    The default implementation is:

        def create_connect_args(self, url):
            opts = url.translate_connect_args()
            opts.update(url.query)
            return [[], opts]

    Parameters:

      url – a `URL` object

    Returns:

      a tuple of `(*args, **kwargs)` which will be passed to the `Dialect.connect()` method.

    See also

    `URL.translate_connect_args()`

  method `sqlalchemy.engine.Dialect.` create_xid()

    Create a two-phase transaction ID.

    This id will be passed to do_begin_twophase(), do_rollback_twophase(), do_commit_twophase(). Its format is unspecified.

  method `sqlalchemy.engine.Dialect.` denormalize_name(name)

    convert the given name to a case insensitive identifier for the backend if it is an all-lowercase name.

    This method is only used if the dialect defines requires_name_normalize=True.

  method `sqlalchemy.engine.Dialect.` do_begin(dbapi_connection)

    Provide an implementation of `connection.begin()`, given a DB-API connection.

    The DBAPI has no dedicated “begin” method and it is expected that transactions are implicit. This hook is provided for those DBAPIs that might need additional help in this area.

    Note that `Dialect.do_begin()` is not called unless a `Transaction` object is in use. The `Dialect.do_autocommit()` hook is provided for DBAPIs that need some extra commands emitted after a commit in order to enter the next transaction, when the SQLAlchemy `Connection` is used in its default “autocommit” mode.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.Dialect.` do_begin_twophase(connection, xid)

    Begin a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

  method `sqlalchemy.engine.Dialect.` do_close(dbapi_connection)

    Provide an implementation of `connection.close()`, given a DBAPI connection.

    This hook is called by the `Pool` when a connection has been detached from the pool, or is being returned beyond the normal capacity of the pool.

  method `sqlalchemy.engine.Dialect.` do_commit(dbapi_connection)

    Provide an implementation of `connection.commit()`, given a DB-API connection.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.Dialect.` do_commit_twophase(connection, xid, is_prepared=True, recover=False)

    Commit a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

      - is_prepared – whether or not `TwoPhaseTransaction.prepare()` was called.

      - recover – if the recover flag was passed.

  method `sqlalchemy.engine.Dialect.` do_execute(cursor, statement, parameters, context=None)

    Provide an implementation of `cursor.execute(statement, parameters)`.

  method `sqlalchemy.engine.Dialect.` do_execute_no_params(cursor, statement, parameters, context=None)

    Provide an implementation of `cursor.execute(statement)`.

    The parameter collection should not be sent.

  method `sqlalchemy.engine.Dialect.` do_executemany(cursor, statement, parameters, context=None)

    Provide an implementation of `cursor.executemany(statement, parameters)`.

  method `sqlalchemy.engine.Dialect.` do_prepare_twophase(connection, xid)

    Prepare a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

  method `sqlalchemy.engine.Dialect.` do_recover_twophase(connection)

    Recover list of uncommitted prepared two phase transaction identifiers on the given connection.

    Parameters:

      connection – a `Connection`.

  method `sqlalchemy.engine.Dialect.` do_release_savepoint(connection, name)

    Release the named savepoint on a connection.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.Dialect.` do_rollback(dbapi_connection)

    Provide an implementation of `connection.rollback()`, given a DB-API connection.

    Parameters:

      dbapi_connection – a DBAPI connection, typically proxied within a `ConnectionFairy`.

  method `sqlalchemy.engine.Dialect.` do_rollback_to_savepoint(connection, name)

    Rollback a connection to the named savepoint.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.Dialect.` do_rollback_twophase(connection, xid, is_prepared=True, recover=False)

    Rollback a two phase transaction on the given connection.

    Parameters:

      - connection – a `Connection`.

      - xid – xid

      - is_prepared – whether or not `TwoPhaseTransaction.prepare()` was called.

      - recover – if the recover flag was passed.

  method `sqlalchemy.engine.Dialect.` do_savepoint(connection, name)

    Create a savepoint with the given name.

    Parameters:

      - connection – a `Connection`.

      - name – savepoint name.

  method `sqlalchemy.engine.Dialect.` do_set_input_sizes(cursor, list_of_tuples, context)

    invoke the cursor.setinputsizes() method with appropriate arguments

    This hook is called if the dialect.use_inputsizes flag is set to True. Parameter data is passed in a list of tuples (paramname, dbtype, sqltype), where `paramname` is the key of the parameter in the statement, `dbtype` is the DBAPI datatype and `sqltype` is the SQLAlchemy type. The order of tuples is in the correct parameter order.

    New in version 1.4.

  method `sqlalchemy.engine.Dialect.` do_terminate(dbapi_connection)

    Provide an implementation of `connection.close()` that tries as much as possible to not block, given a DBAPI connection.

    In the vast majority of cases this just calls .close(), however for some asyncio dialects may call upon different API features.

    This hook is called by the `Pool` when a connection is being recycled or has been invalidated.

    New in version 1.4.41.

  classmethod `sqlalchemy.engine.Dialect.` engine_created(engine)

    A convenience hook called before returning the final `Engine`.

    If the dialect returned a different class from the `get_dialect_cls()` method, then the hook is called on both classes, first on the dialect class returned by the `get_dialect_cls()` method and then on the class on which the method was called.

    The hook should be used by dialects and/or wrappers to apply special events to the engine or its components. In particular, it allows a dialect-wrapping class to apply dialect-level events.

    New in version 1.0.3.

  method `sqlalchemy.engine.Dialect.` get_check_constraints(connection, table_name, schema=None, **kw)

    Return information about check constraints in table_name.

    Given a string table_name and an optional string schema, return check constraint information as a list of dicts with these keys:

    - `name` - the check constraint’s name

    - `sqltext` - the check constraint’s SQL expression

    - `**kw` - other options passed to the dialect’s get_check_constraints() method.

    New in version 1.1.0.

  method `sqlalchemy.engine.Dialect.` get_columns(connection, table_name, schema=None, **kw)

    Return information about columns in table_name.

    Given a `Connection`, a string table_name, and an optional string schema, return column information as a list of dictionaries with these keys:

    name

      the column’s name

    type

      [sqlalchemy.types#TypeEngine]

    nullable

      boolean

    default

      the column’s default value

    autoincrement

      boolean

    sequence
      a dictionary of the form
        {‘name’str, ‘start’ :int, ‘increment’: int, ‘minvalue’: int,

          ‘maxvalue’: int, ‘nominvalue’: bool, ‘nomaxvalue’: bool, ‘cycle’: bool, ‘cache’: int, ‘order’: bool}

    Additional column attributes may be present.

  method `sqlalchemy.engine.Dialect.` get_default_isolation_level(dbapi_conn)

    Given a DBAPI connection, return its isolation level, or a default isolation level if one cannot be retrieved.

    This method may only raise NotImplementedError and must not raise any other exception, as it is used implicitly upon first connect.

    The method must return a value for a dialect that supports isolation level settings, as this level is what will be reverted towards when a per-connection isolation level change is made.

    The method defaults to using the `Dialect.get_isolation_level()` method unless overridden by a dialect.

    New in version 1.3.22.

  classmethod `sqlalchemy.engine.Dialect.` get_dialect_cls(url)

    Given a URL, return the `Dialect` that will be used.

    This is a hook that allows an external plugin to provide functionality around an existing dialect, by allowing the plugin to be loaded from the url based on an entrypoint, and then the plugin returns the actual dialect to be used.

    By default this just returns the cls.

    New in version 1.0.3.

  method `sqlalchemy.engine.Dialect.` get_driver_connection(connection)

    Returns the connection object as returned by the external driver package.

    For normal dialects that use a DBAPI compliant driver this call will just return the `connection` passed as argument. For dialects that instead adapt a non DBAPI compliant driver, like when adapting an asyncio driver, this call will return the connection-like object as returned by the driver.

    New in version 1.4.24.

  method `sqlalchemy.engine.Dialect.` get_foreign_keys(connection, table_name, schema=None, **kw)

    Return information about foreign_keys in table_name.

    Given a `Connection`, a string table_name, and an optional string schema, return foreign key information as a list of dicts with these keys:

    name

      the constraint’s name

    constrained_columns

      a list of column names that make up the foreign key

    referred_schema

      the name of the referred schema

    referred_table

      the name of the referred table

    referred_columns

      a list of column names in the referred table that correspond to constrained_columns

  method `sqlalchemy.engine.Dialect.` get_indexes(connection, table_name, schema=None, **kw)

    Return information about indexes in table_name.

    Given a `Connection`, a string table_name and an optional string schema, return index information as a list of dictionaries with these keys:

    name

      the index’s name

    column_names

      list of column names in order

    unique

      boolean

  method `sqlalchemy.engine.Dialect.` get_isolation_level(dbapi_conn)

    Given a DBAPI connection, return its isolation level.

    When working with a `Connection` object, the corresponding DBAPI connection may be procured using the `Connection.connection` accessor.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  method `sqlalchemy.engine.Dialect.` get_pk_constraint(connection, table_name, schema=None, **kw)

    Return information about the primary key constraint on table_name`.

    Given a `Connection`, a string table_name, and an optional string schema, return primary key information as a dictionary with these keys:

    constrained_columns

      a list of column names that make up the primary key

    name

      optional name of the primary key constraint.

  method `sqlalchemy.engine.Dialect.` get_sequence_names(connection, schema=None, **kw)

    Return a list of all sequence names available in the database.

    Parameters:

      schema – schema name to query, if not the default schema.

    New in version 1.4.

  method `sqlalchemy.engine.Dialect.` get_table_comment(connection, table_name, schema=None, **kw)

    Return the “comment” for the table identified by table_name.

    Given a string table_name and an optional string schema, return table comment information as a dictionary with this key:

    text

      text of the comment

    Raises `NotImplementedError` for dialects that don’t support comments.

    New in version 1.2.

  method `sqlalchemy.engine.Dialect.` get_table_names(connection, schema=None, **kw)

    Return a list of table names for schema.

  method `sqlalchemy.engine.Dialect.` get_temp_table_names(connection, schema=None, **kw)

    Return a list of temporary table names on the given connection, if supported by the underlying backend.

  method `sqlalchemy.engine.Dialect.` get_temp_view_names(connection, schema=None, **kw)

    Return a list of temporary view names on the given connection, if supported by the underlying backend.

  method `sqlalchemy.engine.Dialect.` get_unique_constraints(connection, table_name, schema=None, **kw)

    Return information about unique constraints in table_name.

    Given a string table_name and an optional string schema, return unique constraint information as a list of dicts with these keys:

    name

      the unique constraint’s name

    column_names

      list of column names in order

    **kw

      other options passed to the dialect’s get_unique_constraints() method.

    New in version 0.9.0.

  method `sqlalchemy.engine.Dialect.` get_view_definition(connection, view_name, schema=None, **kw)

    Return view definition.

    Given a `Connection`, a string view_name, and an optional string schema, return the view definition.

  method `sqlalchemy.engine.Dialect.` get_view_names(connection, schema=None, **kw)

    Return a list of all view names available in the database.

    Parameters:

      schema – schema name to query, if not the default schema.

  method `sqlalchemy.engine.Dialect.` has_index(connection, table_name, index_name, schema=None)

    Check the existence of a particular index name in the database.

    Given a `Connection` object, a string table_name and string index name, return True if an index of the given name on the given table exists, false otherwise.

    The `DefaultDialect` implements this in terms of the `Dialect.has_table()` and `Dialect.get_indexes()` methods, however dialects can implement a more performant version.

    New in version 1.4.

  method `sqlalchemy.engine.Dialect.` has_sequence(connection, sequence_name, schema=None, **kw)

    Check the existence of a particular sequence in the database.

    Given a `Connection` object and a string sequence_name, return True if the given sequence exists in the database, False otherwise.

  method `sqlalchemy.engine.Dialect.` has_table(connection, table_name, schema=None, **kw)

    For internal dialect use, check the existence of a particular table in the database.

    Given a `Connection` object, a string table_name and optional schema name, return True if the given table exists in the database, False otherwise.

    This method serves as the underlying implementation of the public facing `Inspector.has_table()` method, and is also used internally to implement the “checkfirst” behavior for methods like `Table.create()` and `MetaData.create_all()`.

    Note

    This method is used internally by SQLAlchemy, and is published so that third-party dialects may provide an implementation. It is not the public API for checking for table presence. Please use the `Inspector.has_table()` method. Alternatively, for legacy cross-compatibility, the `Engine.has_table()` method may be used.

  method `sqlalchemy.engine.Dialect.` initialize(connection)

    Called during strategized creation of the dialect with a connection.

    Allows dialects to configure options based on server version info or other properties.

    The connection passed here is a SQLAlchemy Connection object, with full capabilities.

    The initialize() method of the base dialect should be called via super().

    Note

    as of SQLAlchemy 1.4, this method is called before any `Dialect.on_connect()` hooks are called.

  method `sqlalchemy.engine.Dialect.` is_disconnect(e, connection, cursor)

    Return True if the given DB-API error indicates an invalid connection

  classmethod `sqlalchemy.engine.Dialect.` load_provisioning()

    set up the provision.py module for this dialect.

    For dialects that include a provision.py module that sets up provisioning followers, this method should initiate that process.

    A typical implementation would be:

        @classmethod
        def load_provisioning(cls):
            __import__("mydialect.provision")

    The default method assumes a module named `provision.py` inside the owning package of the current dialect, based on the `__module__` attribute:

        @classmethod
        def load_provisioning(cls):
            package = ".".join(cls.__module__.split(".")[0:-1])
            try:
                __import__(package + ".provision")
            except ImportError:
                pass

    New in version 1.3.14.

  method `sqlalchemy.engine.Dialect.` normalize_name(name)

    convert the given name to lowercase if it is detected as case insensitive.

    This method is only used if the dialect defines requires_name_normalize=True.

  method `sqlalchemy.engine.Dialect.` on_connect()

    return a callable which sets up a newly created DBAPI connection.

    The callable should accept a single argument “conn” which is the DBAPI connection itself. The inner callable has no return value.

    E.g.:

        class MyDialect(default.DefaultDialect):
            # ...

            def on_connect(self):
                def do_on_connect(connection):
                    connection.execute("SET SPECIAL FLAGS etc")

                return do_on_connect

    This is used to set dialect-wide per-connection options such as isolation modes, Unicode modes, etc.

    The “do_on_connect” callable is invoked by using the `PoolEvents.connect()` event hook, then unwrapping the DBAPI connection and passing it into the callable.

    Changed in version 1.4: the on_connect hook is no longer called twice for the first connection of a dialect. The on_connect hook is still called before the `Dialect.initialize()` method however.

    Changed in version 1.4.3: the on_connect hook is invoked from a new method on_connect_url that passes the URL that was used to create the connect args. Dialects can implement on_connect_url instead of on_connect if they need the URL object that was used for the connection in order to get additional context.

    If None is returned, no event listener is generated.

    Returns:

      a callable that accepts a single DBAPI connection as an argument, or None.

    See also

    `Dialect.connect()` - allows the DBAPI `connect()` sequence itself to be controlled.

    `Dialect.on_connect_url()` - supersedes `Dialect.on_connect()` to also receive the `URL` object in context.

  method `sqlalchemy.engine.Dialect.` on_connect_url(url)

    return a callable which sets up a newly created DBAPI connection.

    This method is a new hook that supersedes the `Dialect.on_connect()` method when implemented by a dialect. When not implemented by a dialect, it invokes the `Dialect.on_connect()` method directly to maintain compatibility with existing dialects. There is no deprecation for `Dialect.on_connect()` expected.

    The callable should accept a single argument “conn” which is the DBAPI connection itself. The inner callable has no return value.

    E.g.:

        class MyDialect(default.DefaultDialect):
            # ...

            def on_connect_url(self, url):
                def do_on_connect(connection):
                    connection.execute("SET SPECIAL FLAGS etc")

                return do_on_connect

    This is used to set dialect-wide per-connection options such as isolation modes, Unicode modes, etc.

    This method differs from `Dialect.on_connect()` in that it is passed the `URL` object that’s relevant to the connect args. Normally the only way to get this is from the `Dialect.on_connect()` hook is to look on the `Engine` itself, however this URL object may have been replaced by plugins.

    Note

    The default implementation of `Dialect.on_connect_url()` is to invoke the `Dialect.on_connect()` method. Therefore if a dialect implements this method, the `Dialect.on_connect()` method will not be called unless the overriding dialect calls it directly from here.

    New in version 1.4.3: added `Dialect.on_connect_url()` which normally calls into `Dialect.on_connect()`.

    Parameters:

      url – a `URL` object representing the `URL` that was passed to the `Dialect.create_connect_args()` method.

    Returns:

      a callable that accepts a single DBAPI connection as an argument, or None.

    See also

    `Dialect.on_connect()`

  method `sqlalchemy.engine.Dialect.` reset_isolation_level(dbapi_conn)

    Given a DBAPI connection, revert its isolation to the default.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  method `sqlalchemy.engine.Dialect.` set_isolation_level(dbapi_conn, level)

    Given a DBAPI connection, set its isolation level.

    Note that this is a dialect-level method which is used as part of the implementation of the `Connection` and `Engine` isolation level facilities; these APIs should be preferred for most typical use cases.

    See also

    `Connection.get_isolation_level()` - view current level

    `Connection.default_isolation_level` - view default level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

  attribute `sqlalchemy.engine.Dialect.` supports_statement_cache = True

    indicates if this dialect supports caching.

    All dialects that are compatible with statement caching should set this flag to True directly on each dialect class and subclass that supports it. SQLAlchemy tests that this flag is locally present on each dialect subclass before it will use statement caching. This is to provide safety for legacy or new dialects that are not yet fully tested to be compliant with SQL statement caching.

    New in version 1.4.5.

    See also

    Caching for Third Party Dialects

  classmethod `sqlalchemy.engine.Dialect.` type_descriptor(typeobj)

    Transform a generic type to a dialect-specific type.

    Dialect classes will usually use the `adapt_type()` function in the types module to accomplish this.

    The returned result is cached per dialect class so can contain no dialect-instance state.

class sqlalchemy.engine.default.DefaultExecutionContext

  Members

  create_cursor(), current_parameters, get_current_parameters(), get_lastrowid(), get_out_parameter_values(), get_result_processor(), handle_dbapi_exception(), lastrow_has_defaults(), post_exec(), pre_exec(), should_autocommit_text()

  Class signature

  class `sqlalchemy.engine.default.DefaultExecutionContext` (`sqlalchemy.engine.interfaces.ExecutionContext`)

  method `sqlalchemy.engine.default.DefaultExecutionContext.` create_cursor()

    Return a new cursor generated from this ExecutionContext’s connection.

    Some dialects may wish to change the behavior of connection.cursor(), such as postgresql which may return a PG “server side” cursor.

  attribute `sqlalchemy.engine.default.DefaultExecutionContext.` current_parameters = None

    A dictionary of parameters applied to the current row.

    This attribute is only available in the context of a user-defined default generation function, e.g. as described at Context-Sensitive Default Functions. It consists of a dictionary which includes entries for each column/value pair that is to be part of the INSERT or UPDATE statement. The keys of the dictionary will be the key value of each `Column`, which is usually synonymous with the name.

    Note that the `DefaultExecutionContext.current_parameters` attribute does not accommodate for the “multi-values” feature of the `Insert.values()` method. The `DefaultExecutionContext.get_current_parameters()` method should be preferred.

    See also

    `DefaultExecutionContext.get_current_parameters()`

    Context-Sensitive Default Functions

  method `sqlalchemy.engine.default.DefaultExecutionContext.` get_current_parameters(isolate_multiinsert_groups=True)

    Return a dictionary of parameters applied to the current row.

    This method can only be used in the context of a user-defined default generation function, e.g. as described at Context-Sensitive Default Functions. When invoked, a dictionary is returned which includes entries for each column/value pair that is part of the INSERT or UPDATE statement. The keys of the dictionary will be the key value of each `Column`, which is usually synonymous with the name.

    Parameters:

      isolate_multiinsert_groups=True – indicates that multi-valued INSERT constructs created using `Insert.values()` should be handled by returning only the subset of parameters that are local to the current column default invocation. When `False`, the raw parameters of the statement are returned including the naming convention used in the case of multi-valued INSERT.

    New in version 1.2: added `DefaultExecutionContext.get_current_parameters()` which provides more functionality over the existing `DefaultExecutionContext.current_parameters` attribute.

    See also

    `DefaultExecutionContext.current_parameters`

    Context-Sensitive Default Functions

  method `sqlalchemy.engine.default.DefaultExecutionContext.` get_lastrowid()

    return self.cursor.lastrowid, or equivalent, after an INSERT.

    This may involve calling special cursor functions, issuing a new SELECT on the cursor (or a new one), or returning a stored value that was calculated within post_exec().

    This function will only be called for dialects which support “implicit” primary key generation, keep preexecute_autoincrement_sequences set to False, and when no explicit id value was bound to the statement.

    The function is called once for an INSERT statement that would need to return the last inserted primary key for those dialects that make use of the lastrowid concept. In these cases, it is called directly after `ExecutionContext.post_exec()`.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` get_out_parameter_values(names)

    Return a sequence of OUT parameter values from a cursor.

    For dialects that support OUT parameters, this method will be called when there is a `SQLCompiler` object which has the `SQLCompiler.has_out_parameters` flag set. This flag in turn will be set to True if the statement itself has `BindParameter` objects that have the `.isoutparam` flag set which are consumed by the `SQLCompiler.visit_bindparam()` method. If the dialect compiler produces `BindParameter` objects with `.isoutparam` set which are not handled by `SQLCompiler.visit_bindparam()`, it should set this flag explicitly.

    The list of names that were rendered for each bound parameter is passed to the method. The method should then return a sequence of values corresponding to the list of parameter objects. Unlike in previous SQLAlchemy versions, the values can be the raw values from the DBAPI; the execution context will apply the appropriate type handler based on what’s present in self.compiled.binds and update the values. The processed dictionary will then be made available via the `.out_parameters` collection on the result object. Note that SQLAlchemy 1.4 has multiple kinds of result object as part of the 2.0 transition.

    New in version 1.4: - added `ExecutionContext.get_out_parameter_values()`, which is invoked automatically by the `DefaultExecutionContext` when there are `BindParameter` objects with the `.isoutparam` flag set. This replaces the practice of setting out parameters within the now-removed `get_result_proxy()` method.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` get_result_processor(type_, colname, coltype)

    Return a ‘result processor’ for a given type as present in cursor.description.

    This has a default implementation that dialects can override for context-sensitive result type handling.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` handle_dbapi_exception(e)

    Receive a DBAPI exception which occurred upon execute, result fetch, etc.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` lastrow_has_defaults()

    Return True if the last INSERT or UPDATE row contained inlined or database-side defaults.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` post_exec()

    Called after the execution of a compiled statement.

    If a compiled statement was passed to this ExecutionContext, the last_insert_ids, last_inserted_params, etc. datamembers should be available after this method completes.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` pre_exec()

    Called before an execution of a compiled statement.

    If a compiled statement was passed to this ExecutionContext, the statement and parameters datamembers must be initialized after this statement is complete.

  method `sqlalchemy.engine.default.DefaultExecutionContext.` should_autocommit_text(statement)

    Parse the given textual statement and return True if it refers to a “committable” statement

class sqlalchemy.engine.ExecutionContext

  A messenger object for a Dialect that corresponds to a single execution.

  ExecutionContext should have these data members:

  Members

  create_cursor(), get_out_parameter_values(), get_rowcount(), handle_dbapi_exception(), lastrow_has_defaults(), post_exec(), pre_exec(), should_autocommit_text()

  connection

    Connection object which can be freely used by default value generators to execute SQL. This Connection should reference the same underlying connection/transactional resources of root_connection.

  root_connection

    Connection object which is the source of this ExecutionContext. This Connection may have close_with_result=True set, in which case it can only be used once.

  dialect

    dialect which created this ExecutionContext.

  cursor

    DB-API cursor procured from the connection,

  compiled

    if passed to constructor, sqlalchemy.engine.base.Compiled object being executed,

  statement

    string version of the statement to be executed. Is either passed to the constructor, or must be created from the sql.Compiled object by the time pre_exec() has completed.

  parameters

    bind parameters passed to the execute() method. For compiled statements, this is a dictionary or list of dictionaries. For textual statements, it should be in a format suitable for the dialect’s paramstyle (i.e. dict or list of dicts for non positional, list or list of lists/tuples for positional).

  isinsert

    True if the statement is an INSERT.

  isupdate

    True if the statement is an UPDATE.

  should_autocommit

    True if the statement is a “committable” statement.

  prefetch_cols

    a list of Column objects for which a client-side default was fired off. Applies to inserts and updates.

  postfetch_cols

    a list of Column objects for which a server-side default or inline SQL expression value was fired off. Applies to inserts and updates.

  method `sqlalchemy.engine.ExecutionContext.` create_cursor()

    Return a new cursor generated from this ExecutionContext’s connection.

    Some dialects may wish to change the behavior of connection.cursor(), such as postgresql which may return a PG “server side” cursor.

  method `sqlalchemy.engine.ExecutionContext.` get_out_parameter_values(out_param_names)

    Return a sequence of OUT parameter values from a cursor.

    For dialects that support OUT parameters, this method will be called when there is a `SQLCompiler` object which has the `SQLCompiler.has_out_parameters` flag set. This flag in turn will be set to True if the statement itself has `BindParameter` objects that have the `.isoutparam` flag set which are consumed by the `SQLCompiler.visit_bindparam()` method. If the dialect compiler produces `BindParameter` objects with `.isoutparam` set which are not handled by `SQLCompiler.visit_bindparam()`, it should set this flag explicitly.

    The list of names that were rendered for each bound parameter is passed to the method. The method should then return a sequence of values corresponding to the list of parameter objects. Unlike in previous SQLAlchemy versions, the values can be the raw values from the DBAPI; the execution context will apply the appropriate type handler based on what’s present in self.compiled.binds and update the values. The processed dictionary will then be made available via the `.out_parameters` collection on the result object. Note that SQLAlchemy 1.4 has multiple kinds of result object as part of the 2.0 transition.

    New in version 1.4: - added `ExecutionContext.get_out_parameter_values()`, which is invoked automatically by the `DefaultExecutionContext` when there are `BindParameter` objects with the `.isoutparam` flag set. This replaces the practice of setting out parameters within the now-removed `get_result_proxy()` method.

  method `sqlalchemy.engine.ExecutionContext.` get_rowcount()

    Return the DBAPI `cursor.rowcount` value, or in some cases an interpreted value.

    See `CursorResult.rowcount` for details on this.

  method `sqlalchemy.engine.ExecutionContext.` handle_dbapi_exception(e)

    Receive a DBAPI exception which occurred upon execute, result fetch, etc.

  method `sqlalchemy.engine.ExecutionContext.` lastrow_has_defaults()

    Return True if the last INSERT or UPDATE row contained inlined or database-side defaults.

  method `sqlalchemy.engine.ExecutionContext.` post_exec()

    Called after the execution of a compiled statement.

    If a compiled statement was passed to this ExecutionContext, the last_insert_ids, last_inserted_params, etc. datamembers should be available after this method completes.

  method `sqlalchemy.engine.ExecutionContext.` pre_exec()

    Called before an execution of a compiled statement.

    If a compiled statement was passed to this ExecutionContext, the statement and parameters datamembers must be initialized after this statement is complete.

  method `sqlalchemy.engine.ExecutionContext.` should_autocommit_text(statement)

    Parse the given textual statement and return True if it refers to a “committable” statement

class sqlalchemy.sql.compiler.GenericTypeCompiler(dialect)

  Class signature

  class `sqlalchemy.sql.compiler.GenericTypeCompiler` (`sqlalchemy.sql.compiler.TypeCompiler`)

class sqlalchemy.log.Identified

class sqlalchemy.sql.compiler.IdentifierPreparer(dialect, initial_quote='"', final_quote=None, escape_quote='"', quote_case_sensitive_collations=True, omit_schema=False)

  Members

  __init__(), format_column(), format_label_name(), format_schema(), format_table(), format_table_seq(), quote(), quote_identifier(), quote_schema(), schema_for_object, unformat_identifiers(), validate_sql_phrase()

  Handle quoting and case-folding of identifiers based on options.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` __init__(dialect, initial_quote='"', final_quote=None, escape_quote='"', quote_case_sensitive_collations=True, omit_schema=False)

    Construct a new `IdentifierPreparer` object.

    initial_quote

      Character that begins a delimited identifier.

    final_quote

      Character that ends a delimited identifier. Defaults to initial_quote.

    omit_schema

      Prevent prepending schema name. Useful for databases that do not support schemae.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` format_column(column, use_table=False, name=None, table_name=None, use_schema=False, anon_map=None)

    Prepare a quoted column name.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` format_label_name(name, anon_map=None)

    Prepare a quoted column name.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` format_schema(name)

    Prepare a quoted schema name.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` format_table(table, use_schema=True, name=None)

    Prepare a quoted table and schema name.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` format_table_seq(table, use_schema=True)

    Format table name and schema as a tuple.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` quote(ident, force=None)

    Conditionally quote an identifier.

    The identifier is quoted if it is a reserved word, contains quote-necessary characters, or is an instance of `quoted_name` which includes `quote` set to `True`.

    Subclasses can override this to provide database-dependent quoting behavior for identifier names.

    Parameters:

      - ident – string identifier

      - force –

        unused

        Deprecated since version 0.9: The `IdentifierPreparer.quote.force` parameter is deprecated and will be removed in a future release. This flag has no effect on the behavior of the `IdentifierPreparer.quote()` method; please refer to `quoted_name`.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` quote_identifier(value)

    Quote an identifier.

    Subclasses should override this to provide database-dependent quoting behavior.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` quote_schema(schema, force=None)

    Conditionally quote a schema name.

    The name is quoted if it is a reserved word, contains quote-necessary characters, or is an instance of `quoted_name` which includes `quote` set to `True`.

    Subclasses can override this to provide database-dependent quoting behavior for schema names.

    Parameters:

      - schema – string schema name

      - force –

        unused

        Deprecated since version 0.9: The `IdentifierPreparer.quote_schema.force` parameter is deprecated and will be removed in a future release. This flag has no effect on the behavior of the `IdentifierPreparer.quote()` method; please refer to `quoted_name`.

  attribute `sqlalchemy.sql.compiler.IdentifierPreparer.` schema_for_object = operator.attrgetter('schema')

    Return the .schema attribute for an object.

    For the default IdentifierPreparer, the schema for an object is always the value of the “.schema” attribute. if the preparer is replaced with one that has a non-empty schema_translate_map, the value of the “.schema” attribute is rendered a symbol that will be converted to a real schema name from the mapping post-compile.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` unformat_identifiers(identifiers)

    Unpack ‘schema.table.column’-like strings into components.

  method `sqlalchemy.sql.compiler.IdentifierPreparer.` validate_sql_phrase(element, reg)

    keyword sequence filter.

    a filter for elements that are intended to represent keyword sequences, such as “INITIALLY”, “INITIALLY DEFERRED”, etc. no special characters should be present.

    New in version 1.3.

class sqlalchemy.sql.compiler.SQLCompiler(dialect, statement, cache_key=None, column_keys=None, for_executemany=False, linting=symbol('NO_LINTING'), **kwargs)

  Default implementation of `Compiled`.

  Compiles `ClauseElement` objects into SQL strings.

  Members

  __init__(), ansi_bind_rules, construct_params(), current_executable, default_from(), delete_extra_from_clause(), escaped_bind_names, get_select_precolumns(), group_by_clause(), has_out_parameters, insert_single_values_expr, isdelete, literal_execute_params, order_by_clause(), params, positiontup, post_compile_params, postfetch_lastrowid, render_literal_value(), render_table_with_column_in_update_from, returning, returning_precedes_values, sql_compiler, translate_select_structure, update_from_clause(), update_limit_clause(), update_tables_clause()

  Class signature

  class `sqlalchemy.sql.compiler.SQLCompiler` (`sqlalchemy.sql.compiler.Compiled`)

  method `sqlalchemy.sql.compiler.SQLCompiler.` __init__(dialect, statement, cache_key=None, column_keys=None, for_executemany=False, linting=symbol('NO_LINTING'), **kwargs)

    Construct a new `SQLCompiler` object.

    Parameters:

      - dialect – `Dialect` to be used

      - statement – `ClauseElement` to be compiled

      - column_keys – a list of column names to be compiled into an INSERT or UPDATE statement.

      - for_executemany – whether INSERT / UPDATE statements should expect that they are to be invoked in an “executemany” style, which may impact how the statement will be expected to return the values of defaults and autoincrement / sequences and similar. Depending on the backend and driver in use, support for retrieving these values may be disabled which means SQL expressions may be rendered inline, RETURNING may not be rendered, etc.

      - kwargs – additional keyword arguments to be consumed by the superclass.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` ansi_bind_rules = False

    SQL 92 doesn’t allow bind parameters to be used in the columns clause of a SELECT, nor does it allow ambiguous expressions like “? = ?”. A compiler subclass can set this flag to False if the target driver/DB enforces this

  method `sqlalchemy.sql.compiler.SQLCompiler.` construct_params(params=None, _group_number=None, _check=True, extracted_parameters=None, escape_names=True)

    return a dictionary of bind parameter keys and values

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` current_executable

    Return the current ‘executable’ that is being compiled.

    This is currently the `Select`, `Insert`, `Update`, `Delete`, `CompoundSelect` object that is being compiled. Specifically it’s assigned to the `self.stack` list of elements.

    When a statement like the above is being compiled, it normally is also assigned to the `.statement` attribute of the `Compiler` object. However, all SQL constructs are ultimately nestable, and this attribute should never be consulted by a `visit_` method, as it is not guaranteed to be assigned nor guaranteed to correspond to the current statement being compiled.

    New in version 1.3.21: For compatibility with previous versions, use the following recipe:

        statement = getattr(self, "current_executable", False)
        if statement is False:
            statement = self.stack[-1]["selectable"]

    For versions 1.4 and above, ensure only .current_executable is used; the format of “self.stack” may change.

  method `sqlalchemy.sql.compiler.SQLCompiler.` default_from()

    Called when a SELECT statement has no froms, and no FROM clause is to be appended.

    Gives Oracle a chance to tack on a `FROM DUAL` to the string output.

  method `sqlalchemy.sql.compiler.SQLCompiler.` delete_extra_from_clause(update_stmt, from_table, extra_froms, from_hints, **kw)

    Provide a hook to override the generation of an DELETE..FROM clause.

    This can be used to implement DELETE..USING for example.

    MySQL and MSSQL override this.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` escaped_bind_names = {}

    Late escaping of bound parameter names that has to be converted to the original name when looking in the parameter dictionary.

  method `sqlalchemy.sql.compiler.SQLCompiler.` get_select_precolumns(select, **kw)

    Called when building a `SELECT` statement, position is just before column list.

  method `sqlalchemy.sql.compiler.SQLCompiler.` group_by_clause(select, **kw)

    allow dialects to customize how GROUP BY is rendered.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` has_out_parameters = False

    if True, there are bindparam() objects that have the isoutparam flag set.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` insert_single_values_expr = None

    When an INSERT is compiled with a single set of parameters inside a VALUES expression, the string is assigned here, where it can be used for insert batching schemes to rewrite the VALUES expression.

    New in version 1.3.8.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` isdelete = False

    class-level defaults which can be set at the instance level to define if this Compiled instance represents INSERT/UPDATE/DELETE

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` literal_execute_params = frozenset({})

    bindparameter objects that are rendered as literal values at statement execution time.

  method `sqlalchemy.sql.compiler.SQLCompiler.` order_by_clause(select, **kw)

    allow dialects to customize how ORDER BY is rendered.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` params

    Return the bind param dictionary embedded into this compiled object, for those values that are present.

    See also

    How do I render SQL expressions as strings, possibly with bound parameters inlined? - includes a usage example for debugging use cases.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` positiontup = None

    for a compiled construct that uses a positional paramstyle, will be a sequence of strings, indicating the names of bound parameters in order.

    This is used in order to render bound parameters in their correct order, and is combined with the `Compiled.params` dictionary to render parameters.

    See also

    How do I render SQL expressions as strings, possibly with bound parameters inlined? - includes a usage example for debugging use cases.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` post_compile_params = frozenset({})

    bindparameter objects that are rendered as bound parameter placeholders at statement execution time.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` postfetch_lastrowid = False

    if True, and this in insert, use cursor.lastrowid to populate result.inserted_primary_key.

  method `sqlalchemy.sql.compiler.SQLCompiler.` render_literal_value(value, type_)

    Render the value of a bind parameter as a quoted literal.

    This is used for statement sections that do not accept bind parameters on the target driver/database.

    This should be implemented by subclasses using the quoting services of the DBAPI.

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` render_table_with_column_in_update_from = False

    set to True classwide to indicate the SET clause in a multi-table UPDATE statement should qualify columns with the table name (i.e. MySQL only)

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` returning = None

    holds the “returning” collection of columns if the statement is CRUD and defines returning columns either implicitly or explicitly

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` returning_precedes_values = False

    set to True classwide to generate RETURNING clauses before the VALUES or WHERE clause (i.e. MSSQL)

  attribute `sqlalchemy.sql.compiler.SQLCompiler.` sql_compiler
  attribute `sqlalchemy.sql.compiler.SQLCompiler.` translate_select_structure = None

    if not `None`, should be a callable which accepts `(select_stmt, **kw)` and returns a select object. this is used for structural changes mostly to accommodate for LIMIT/OFFSET schemes

  method `sqlalchemy.sql.compiler.SQLCompiler.` update_from_clause(update_stmt, from_table, extra_froms, from_hints, **kw)

    Provide a hook to override the generation of an UPDATE..FROM clause.

    MySQL and MSSQL override this.

  method `sqlalchemy.sql.compiler.SQLCompiler.` update_limit_clause(update_stmt)

    Provide a hook for MySQL to add LIMIT to the UPDATE

  method `sqlalchemy.sql.compiler.SQLCompiler.` update_tables_clause(update_stmt, from_table, extra_froms, **kw)

    Provide a hook to override the initial table clause in an UPDATE statement.

    MySQL overrides this.

class sqlalchemy.sql.compiler.StrSQLCompiler(dialect, statement, cache_key=None, column_keys=None, for_executemany=False, linting=symbol('NO_LINTING'), **kwargs)

  A `SQLCompiler` subclass which allows a small selection of non-standard SQL features to render into a string value.

  The `StrSQLCompiler` is invoked whenever a Core expression element is directly stringified without calling upon the `ClauseElement.compile()` method. It can render a limited set of non-standard SQL constructs to assist in basic stringification, however for more substantial custom or dialect-specific SQL constructs, it will be necessary to make use of `ClauseElement.compile()` directly.

  See also

  How do I render SQL expressions as strings, possibly with bound parameters inlined?

  Members

  delete_extra_from_clause(), update_from_clause()

  Class signature

  class `sqlalchemy.sql.compiler.StrSQLCompiler` (`sqlalchemy.sql.compiler.SQLCompiler`)

  method `sqlalchemy.sql.compiler.StrSQLCompiler.` delete_extra_from_clause(update_stmt, from_table, extra_froms, from_hints, **kw)

    Provide a hook to override the generation of an DELETE..FROM clause.

    This can be used to implement DELETE..USING for example.

    MySQL and MSSQL override this.

  method `sqlalchemy.sql.compiler.StrSQLCompiler.` update_from_clause(update_stmt, from_table, extra_froms, from_hints, **kw)

    Provide a hook to override the generation of an UPDATE..FROM clause.

    MySQL and MSSQL override this.

class sqlalchemy.engine.AdaptedConnection

  Interface of an adapted connection object to support the DBAPI protocol.

  Used by asyncio dialects to provide a sync-style pep-249 facade on top of the asyncio connection/cursor API provided by the driver.

  Members

  driver_connection, run_async()

  New in version 1.4.24.

  attribute `sqlalchemy.engine.AdaptedConnection.` driver_connection

    The connection object as returned by the driver after a connect.

  method `sqlalchemy.engine.AdaptedConnection.` run_async(fn)

    Run the awaitable returned by the given function, which is passed the raw asyncio driver connection.

    This is used to invoke awaitable-only methods on the driver connection within the context of a “synchronous” method, like a connection pool event handler.

    E.g.:

        engine = create_async_engine(...)

        @event.listens_for(engine.sync_engine, "connect")
        def register_custom_types(dbapi_connection, ...):
            dbapi_connection.run_async(
                lambda connection: connection.set_type_codec(
                    'MyCustomType', encoder, decoder, ...
                )
            )

    New in version 1.4.30.

    See also

    Using awaitable-only driver methods in connection pool and other events