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| author | Mike Bayer <mike_mp@zzzcomputing.com> | 2021-04-01 17:20:31 -0400 |
|---|---|---|
| committer | Mike Bayer <mike_mp@zzzcomputing.com> | 2021-04-01 18:59:41 -0400 |
| commit | 20c0f774e5517514da811bc446812baa6b1f32f1 (patch) | |
| tree | 31130474fc5aabcd7143ac5b0ba585c25700169a /lib | |
| parent | dc5ade010da55c1158ee7294c9e882cc52cd6e01 (diff) | |
| download | sqlalchemy-20c0f774e5517514da811bc446812baa6b1f32f1.tar.gz | |
Default caching to opt-out for 3rd party dialects
Added a new flag to the :class:`_engine.Dialect` class called
:attr:`_engine.Dialect.supports_statement_cache`. This flag now needs to be present
directly on a dialect class in order for SQLAlchemy's
:ref:`query cache <sql_caching>` to take effect for that dialect. The
rationale is based on discovered issues such as :ticket:`6173` revealing
that dialects which hardcode literal values from the compiled statement,
often the numerical parameters used for LIMIT / OFFSET, will not be
compatible with caching until these dialects are revised to use the
parameters present in the statement only. For third party dialects where
this flag is not applied, the SQL logging will show the message "dialect
does not support caching", indicating the dialect should seek to apply this
flag once they have verified that no per-statement literal values are being
rendered within the compilation phase.
Fixes: #6184
Change-Id: I6fd5b5d94200458d4cb0e14f2f556dbc25e27e22
Diffstat (limited to 'lib')
38 files changed, 114 insertions, 17 deletions
diff --git a/lib/sqlalchemy/dialects/firebird/base.py b/lib/sqlalchemy/dialects/firebird/base.py index 7fc914f1b..fcf0c31d3 100644 --- a/lib/sqlalchemy/dialects/firebird/base.py +++ b/lib/sqlalchemy/dialects/firebird/base.py @@ -623,6 +623,7 @@ class FBDialect(default.DefaultDialect): """Firebird dialect""" name = "firebird" + supports_statement_cache = True max_identifier_length = 31 diff --git a/lib/sqlalchemy/dialects/firebird/fdb.py b/lib/sqlalchemy/dialects/firebird/fdb.py index 14954b073..18ed65f45 100644 --- a/lib/sqlalchemy/dialects/firebird/fdb.py +++ b/lib/sqlalchemy/dialects/firebird/fdb.py @@ -66,6 +66,8 @@ from ... import util class FBDialect_fdb(FBDialect_kinterbasdb): + supports_statement_cache = True + def __init__(self, enable_rowcount=True, retaining=False, **kwargs): super(FBDialect_fdb, self).__init__( enable_rowcount=enable_rowcount, retaining=retaining, **kwargs diff --git a/lib/sqlalchemy/dialects/firebird/kinterbasdb.py b/lib/sqlalchemy/dialects/firebird/kinterbasdb.py index 4c937e0de..7c91db639 100644 --- a/lib/sqlalchemy/dialects/firebird/kinterbasdb.py +++ b/lib/sqlalchemy/dialects/firebird/kinterbasdb.py @@ -78,6 +78,7 @@ class FBExecutionContext_kinterbasdb(FBExecutionContext): class FBDialect_kinterbasdb(FBDialect): driver = "kinterbasdb" + supports_statement_cache = True supports_sane_rowcount = False supports_sane_multi_rowcount = False execution_ctx_cls = FBExecutionContext_kinterbasdb diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py index bfa1cf08c..1fef42c53 100644 --- a/lib/sqlalchemy/dialects/mssql/base.py +++ b/lib/sqlalchemy/dialects/mssql/base.py @@ -2576,6 +2576,7 @@ def _schema_elements(schema): class MSDialect(default.DefaultDialect): # will assume it's at least mssql2005 name = "mssql" + supports_statement_cache = True supports_default_values = True supports_empty_insert = False execution_ctx_cls = MSExecutionContext diff --git a/lib/sqlalchemy/dialects/mssql/mxodbc.py b/lib/sqlalchemy/dialects/mssql/mxodbc.py index da4e45f07..637b04869 100644 --- a/lib/sqlalchemy/dialects/mssql/mxodbc.py +++ b/lib/sqlalchemy/dialects/mssql/mxodbc.py @@ -126,6 +126,7 @@ class MSDialect_mxodbc(MxODBCConnector, MSDialect): # this is only needed if "native ODBC" mode is used, # which is now disabled by default. # statement_compiler = MSSQLStrictCompiler + supports_statement_cache = True execution_ctx_cls = MSExecutionContext_mxodbc diff --git a/lib/sqlalchemy/dialects/mssql/pymssql.py b/lib/sqlalchemy/dialects/mssql/pymssql.py index 5110badb9..4cc6c4696 100644 --- a/lib/sqlalchemy/dialects/mssql/pymssql.py +++ b/lib/sqlalchemy/dialects/mssql/pymssql.py @@ -65,6 +65,7 @@ class MSIdentifierPreparer_pymssql(MSIdentifierPreparer): class MSDialect_pymssql(MSDialect): + supports_statement_cache = True supports_native_decimal = True driver = "pymssql" diff --git a/lib/sqlalchemy/dialects/mssql/pyodbc.py b/lib/sqlalchemy/dialects/mssql/pyodbc.py index 6b2fffc4e..99ab37228 100644 --- a/lib/sqlalchemy/dialects/mssql/pyodbc.py +++ b/lib/sqlalchemy/dialects/mssql/pyodbc.py @@ -431,6 +431,7 @@ class MSExecutionContext_pyodbc(MSExecutionContext): class MSDialect_pyodbc(PyODBCConnector, MSDialect): + supports_statement_cache = True # mssql still has problems with this on Linux supports_sane_rowcount_returning = False diff --git a/lib/sqlalchemy/dialects/mysql/aiomysql.py b/lib/sqlalchemy/dialects/mysql/aiomysql.py index c8c7c0f97..6c77e7525 100644 --- a/lib/sqlalchemy/dialects/mysql/aiomysql.py +++ b/lib/sqlalchemy/dialects/mysql/aiomysql.py @@ -266,6 +266,7 @@ class AsyncAdapt_aiomysql_dbapi: class MySQLDialect_aiomysql(MySQLDialect_pymysql): driver = "aiomysql" + supports_statement_cache = True supports_server_side_cursors = True _sscursor = AsyncAdapt_aiomysql_ss_cursor diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py index b3c338bad..986ed8757 100644 --- a/lib/sqlalchemy/dialects/mysql/base.py +++ b/lib/sqlalchemy/dialects/mysql/base.py @@ -2511,6 +2511,8 @@ class MySQLDialect(default.DefaultDialect): """ name = "mysql" + supports_statement_cache = True + supports_alter = True # MySQL has no true "boolean" type; we diff --git a/lib/sqlalchemy/dialects/mysql/cymysql.py b/lib/sqlalchemy/dialects/mysql/cymysql.py index 0d7ba5594..ec9fd6edd 100644 --- a/lib/sqlalchemy/dialects/mysql/cymysql.py +++ b/lib/sqlalchemy/dialects/mysql/cymysql.py @@ -43,6 +43,7 @@ class _cymysqlBIT(BIT): class MySQLDialect_cymysql(MySQLDialect_mysqldb): driver = "cymysql" + supports_statement_cache = True description_encoding = None supports_sane_rowcount = True diff --git a/lib/sqlalchemy/dialects/mysql/mariadb.py b/lib/sqlalchemy/dialects/mysql/mariadb.py index 0dbb579e8..8ebde462b 100644 --- a/lib/sqlalchemy/dialects/mysql/mariadb.py +++ b/lib/sqlalchemy/dialects/mysql/mariadb.py @@ -3,6 +3,7 @@ from .base import MySQLDialect class MariaDBDialect(MySQLDialect): is_mariadb = True + supports_statement_cache = True name = "mariadb" @@ -18,5 +19,5 @@ def loader(driver): MariaDBDialect, driver_cls, ), - {}, + {"supports_statement_cache": True}, ) diff --git a/lib/sqlalchemy/dialects/mysql/mariadbconnector.py b/lib/sqlalchemy/dialects/mysql/mariadbconnector.py index ddc11f6e6..6e3a24950 100644 --- a/lib/sqlalchemy/dialects/mysql/mariadbconnector.py +++ b/lib/sqlalchemy/dialects/mysql/mariadbconnector.py @@ -57,6 +57,7 @@ class MySQLIdentifierPreparer_mariadbconnector(MySQLIdentifierPreparer): class MySQLDialect_mariadbconnector(MySQLDialect): driver = "mariadbconnector" + supports_statement_cache = True # set this to True at the module level to prevent the driver from running # against a backend that server detects as MySQL. currently this appears to diff --git a/lib/sqlalchemy/dialects/mysql/mysqlconnector.py b/lib/sqlalchemy/dialects/mysql/mysqlconnector.py index 5ed675b13..80f20688b 100644 --- a/lib/sqlalchemy/dialects/mysql/mysqlconnector.py +++ b/lib/sqlalchemy/dialects/mysql/mysqlconnector.py @@ -85,6 +85,7 @@ class _myconnpyBIT(BIT): class MySQLDialect_mysqlconnector(MySQLDialect): driver = "mysqlconnector" + supports_statement_cache = True supports_unicode_binds = True diff --git a/lib/sqlalchemy/dialects/mysql/mysqldb.py b/lib/sqlalchemy/dialects/mysql/mysqldb.py index 0318b5077..274f3eea4 100644 --- a/lib/sqlalchemy/dialects/mysql/mysqldb.py +++ b/lib/sqlalchemy/dialects/mysql/mysqldb.py @@ -77,6 +77,7 @@ class MySQLIdentifierPreparer_mysqldb(MySQLIdentifierPreparer): class MySQLDialect_mysqldb(MySQLDialect): driver = "mysqldb" + supports_statement_cache = True supports_unicode_statements = True supports_sane_rowcount = True supports_sane_multi_rowcount = True diff --git a/lib/sqlalchemy/dialects/mysql/oursql.py b/lib/sqlalchemy/dialects/mysql/oursql.py index 5c8c7b7c2..06a6115b4 100644 --- a/lib/sqlalchemy/dialects/mysql/oursql.py +++ b/lib/sqlalchemy/dialects/mysql/oursql.py @@ -55,6 +55,7 @@ class MySQLExecutionContext_oursql(MySQLExecutionContext): class MySQLDialect_oursql(MySQLDialect): driver = "oursql" + supports_statement_cache = True if util.py2k: supports_unicode_binds = True diff --git a/lib/sqlalchemy/dialects/mysql/pymysql.py b/lib/sqlalchemy/dialects/mysql/pymysql.py index 0c321f854..09b5abffe 100644 --- a/lib/sqlalchemy/dialects/mysql/pymysql.py +++ b/lib/sqlalchemy/dialects/mysql/pymysql.py @@ -35,6 +35,7 @@ from ...util import py3k class MySQLDialect_pymysql(MySQLDialect_mysqldb): driver = "pymysql" + supports_statement_cache = True description_encoding = None diff --git a/lib/sqlalchemy/dialects/mysql/pyodbc.py b/lib/sqlalchemy/dialects/mysql/pyodbc.py index 048586b59..7bc9ff14f 100644 --- a/lib/sqlalchemy/dialects/mysql/pyodbc.py +++ b/lib/sqlalchemy/dialects/mysql/pyodbc.py @@ -72,6 +72,7 @@ class MySQLExecutionContext_pyodbc(MySQLExecutionContext): class MySQLDialect_pyodbc(PyODBCConnector, MySQLDialect): + supports_statement_cache = True colspecs = util.update_copy(MySQLDialect.colspecs, {Time: _pyodbcTIME}) supports_unicode_statements = True execution_ctx_cls = MySQLExecutionContext_pyodbc diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py index 46fcbbbe1..11ad61675 100644 --- a/lib/sqlalchemy/dialects/oracle/base.py +++ b/lib/sqlalchemy/dialects/oracle/base.py @@ -1093,10 +1093,10 @@ class OracleCompiler(compiler.SQLCompiler): offset_clause = select._offset_clause if select._simple_int_clause(limit_clause): - limit_clause = limit_clause._render_literal_execute() + limit_clause = limit_clause.render_literal_execute() if select._simple_int_clause(offset_clause): - offset_clause = offset_clause._render_literal_execute() + offset_clause = offset_clause.render_literal_execute() # currently using form at: # https://blogs.oracle.com/oraclemagazine/\ @@ -1434,6 +1434,7 @@ class OracleExecutionContext(default.DefaultExecutionContext): class OracleDialect(default.DefaultDialect): name = "oracle" + supports_statement_cache = True supports_alter = True supports_unicode_statements = False supports_unicode_binds = False diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py index 38b92117b..87c817066 100644 --- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py +++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py @@ -797,6 +797,7 @@ class OracleExecutionContext_cx_oracle(OracleExecutionContext): class OracleDialect_cx_oracle(OracleDialect): + supports_statement_cache = True execution_ctx_cls = OracleExecutionContext_cx_oracle statement_compiler = OracleCompiler_cx_oracle diff --git a/lib/sqlalchemy/dialects/postgresql/asyncpg.py b/lib/sqlalchemy/dialects/postgresql/asyncpg.py index 4580421f6..8cd5bee41 100644 --- a/lib/sqlalchemy/dialects/postgresql/asyncpg.py +++ b/lib/sqlalchemy/dialects/postgresql/asyncpg.py @@ -850,6 +850,7 @@ _pg_types = { class PGDialect_asyncpg(PGDialect): driver = "asyncpg" + supports_statement_cache = True supports_unicode_statements = True supports_server_side_cursors = True diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py index 97eb07bdb..2c4e316b3 100644 --- a/lib/sqlalchemy/dialects/postgresql/base.py +++ b/lib/sqlalchemy/dialects/postgresql/base.py @@ -3062,6 +3062,7 @@ class PGDeferrableConnectionCharacteristic( class PGDialect(default.DefaultDialect): name = "postgresql" + supports_statement_cache = True supports_alter = True max_identifier_length = 63 supports_sane_rowcount = True diff --git a/lib/sqlalchemy/dialects/postgresql/pg8000.py b/lib/sqlalchemy/dialects/postgresql/pg8000.py index 43df6edea..eaf6ccbb8 100644 --- a/lib/sqlalchemy/dialects/postgresql/pg8000.py +++ b/lib/sqlalchemy/dialects/postgresql/pg8000.py @@ -252,6 +252,7 @@ class PGIdentifierPreparer_pg8000(PGIdentifierPreparer): class PGDialect_pg8000(PGDialect): driver = "pg8000" + supports_statement_cache = True supports_unicode_statements = True diff --git a/lib/sqlalchemy/dialects/postgresql/psycopg2.py b/lib/sqlalchemy/dialects/postgresql/psycopg2.py index 16f9ecefa..c2b679022 100644 --- a/lib/sqlalchemy/dialects/postgresql/psycopg2.py +++ b/lib/sqlalchemy/dialects/postgresql/psycopg2.py @@ -634,6 +634,9 @@ EXECUTEMANY_VALUES_PLUS_BATCH = util.symbol( class PGDialect_psycopg2(PGDialect): driver = "psycopg2" + + supports_statement_cache = True + if util.py2k: # turn off supports_unicode_statements for Python 2. psycopg2 supports # unicode statements in Py2K. But! it does not support unicode *bound diff --git a/lib/sqlalchemy/dialects/postgresql/psycopg2cffi.py b/lib/sqlalchemy/dialects/postgresql/psycopg2cffi.py index a449f9e65..780244be9 100644 --- a/lib/sqlalchemy/dialects/postgresql/psycopg2cffi.py +++ b/lib/sqlalchemy/dialects/postgresql/psycopg2cffi.py @@ -28,6 +28,7 @@ from .psycopg2 import PGDialect_psycopg2 class PGDialect_psycopg2cffi(PGDialect_psycopg2): driver = "psycopg2cffi" supports_unicode_statements = True + supports_statement_cache = True # psycopg2cffi's first release is 2.5.0, but reports # __version__ as 2.4.4. Subsequent releases seem to have diff --git a/lib/sqlalchemy/dialects/postgresql/pygresql.py b/lib/sqlalchemy/dialects/postgresql/pygresql.py index 64dd7262d..718bbf78f 100644 --- a/lib/sqlalchemy/dialects/postgresql/pygresql.py +++ b/lib/sqlalchemy/dialects/postgresql/pygresql.py @@ -193,6 +193,7 @@ class _PGIdentifierPreparer(PGIdentifierPreparer): class PGDialect_pygresql(PGDialect): driver = "pygresql" + supports_statement_cache = True statement_compiler = _PGCompiler preparer = _PGIdentifierPreparer diff --git a/lib/sqlalchemy/dialects/postgresql/pypostgresql.py b/lib/sqlalchemy/dialects/postgresql/pypostgresql.py index 6e4db217d..7d4783867 100644 --- a/lib/sqlalchemy/dialects/postgresql/pypostgresql.py +++ b/lib/sqlalchemy/dialects/postgresql/pypostgresql.py @@ -52,6 +52,7 @@ class PGExecutionContext_pypostgresql(PGExecutionContext): class PGDialect_pypostgresql(PGDialect): driver = "pypostgresql" + supports_statement_cache = True supports_unicode_statements = True supports_unicode_binds = True description_encoding = None diff --git a/lib/sqlalchemy/dialects/sqlite/aiosqlite.py b/lib/sqlalchemy/dialects/sqlite/aiosqlite.py index e4b7d1d52..1d09a619d 100644 --- a/lib/sqlalchemy/dialects/sqlite/aiosqlite.py +++ b/lib/sqlalchemy/dialects/sqlite/aiosqlite.py @@ -299,6 +299,7 @@ class SQLiteExecutionContext_aiosqlite(SQLiteExecutionContext): class SQLiteDialect_aiosqlite(SQLiteDialect_pysqlite): driver = "aiosqlite" + supports_statement_cache = True is_async = True diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py index 691ca642d..83c2a8ea7 100644 --- a/lib/sqlalchemy/dialects/sqlite/base.py +++ b/lib/sqlalchemy/dialects/sqlite/base.py @@ -1796,6 +1796,7 @@ class SQLiteDialect(default.DefaultDialect): supports_cast = True supports_multivalues_insert = True tuple_in_values = True + supports_statement_cache = True default_paramstyle = "qmark" execution_ctx_cls = SQLiteExecutionContext diff --git a/lib/sqlalchemy/dialects/sqlite/pysqlcipher.py b/lib/sqlalchemy/dialects/sqlite/pysqlcipher.py index 8f0f46acb..ff02d4dee 100644 --- a/lib/sqlalchemy/dialects/sqlite/pysqlcipher.py +++ b/lib/sqlalchemy/dialects/sqlite/pysqlcipher.py @@ -98,6 +98,7 @@ from ... import util class SQLiteDialect_pysqlcipher(SQLiteDialect_pysqlite): driver = "pysqlcipher" + supports_statement_cache = True pragmas = ("kdf_iter", "cipher", "cipher_page_size", "cipher_use_hmac") diff --git a/lib/sqlalchemy/dialects/sqlite/pysqlite.py b/lib/sqlalchemy/dialects/sqlite/pysqlite.py index c940faf38..0b091e73b 100644 --- a/lib/sqlalchemy/dialects/sqlite/pysqlite.py +++ b/lib/sqlalchemy/dialects/sqlite/pysqlite.py @@ -443,6 +443,7 @@ class _SQLite_pysqliteDate(DATE): class SQLiteDialect_pysqlite(SQLiteDialect): default_paramstyle = "qmark" + supports_statement_cache = True colspecs = util.update_copy( SQLiteDialect.colspecs, diff --git a/lib/sqlalchemy/dialects/sybase/base.py b/lib/sqlalchemy/dialects/sybase/base.py index 49243be78..fd5e5b3b6 100644 --- a/lib/sqlalchemy/dialects/sybase/base.py +++ b/lib/sqlalchemy/dialects/sybase/base.py @@ -632,6 +632,7 @@ class SybaseDialect(default.DefaultDialect): supports_unicode_statements = False supports_sane_rowcount = False supports_sane_multi_rowcount = False + supports_statement_cache = True supports_native_boolean = False supports_unicode_binds = False diff --git a/lib/sqlalchemy/dialects/sybase/mxodbc.py b/lib/sqlalchemy/dialects/sybase/mxodbc.py index 6b2f07c54..7002217c0 100644 --- a/lib/sqlalchemy/dialects/sybase/mxodbc.py +++ b/lib/sqlalchemy/dialects/sybase/mxodbc.py @@ -28,6 +28,7 @@ class SybaseExecutionContext_mxodbc(SybaseExecutionContext): class SybaseDialect_mxodbc(MxODBCConnector, SybaseDialect): execution_ctx_cls = SybaseExecutionContext_mxodbc + supports_statement_cache = True dialect = SybaseDialect_mxodbc diff --git a/lib/sqlalchemy/dialects/sybase/pyodbc.py b/lib/sqlalchemy/dialects/sybase/pyodbc.py index bbd6d968a..bbaaa7e02 100644 --- a/lib/sqlalchemy/dialects/sybase/pyodbc.py +++ b/lib/sqlalchemy/dialects/sybase/pyodbc.py @@ -77,6 +77,7 @@ class SybaseExecutionContext_pyodbc(SybaseExecutionContext): class SybaseDialect_pyodbc(PyODBCConnector, SybaseDialect): execution_ctx_cls = SybaseExecutionContext_pyodbc + supports_statement_cache = True colspecs = {sqltypes.Numeric: _SybNumeric_pyodbc} diff --git a/lib/sqlalchemy/dialects/sybase/pysybase.py b/lib/sqlalchemy/dialects/sybase/pysybase.py index d6d2f2ed2..0c5557e99 100644 --- a/lib/sqlalchemy/dialects/sybase/pysybase.py +++ b/lib/sqlalchemy/dialects/sybase/pysybase.py @@ -62,6 +62,8 @@ class SybaseDialect_pysybase(SybaseDialect): execution_ctx_cls = SybaseExecutionContext_pysybase statement_compiler = SybaseSQLCompiler_pysybase + supports_statement_cache = True + colspecs = {sqltypes.Numeric: _SybNumeric, sqltypes.Float: sqltypes.Float} @classmethod diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py index 7391e7b01..5193a0273 100644 --- a/lib/sqlalchemy/engine/default.py +++ b/lib/sqlalchemy/engine/default.py @@ -44,6 +44,7 @@ CACHE_HIT = util.symbol("CACHE_HIT") CACHE_MISS = util.symbol("CACHE_MISS") CACHING_DISABLED = util.symbol("CACHING_DISABLED") NO_CACHE_KEY = util.symbol("NO_CACHE_KEY") +NO_DIALECT_SUPPORT = util.symbol("NO_DIALECT_SUPPORT") class DefaultDialect(interfaces.Dialect): @@ -57,6 +58,7 @@ class DefaultDialect(interfaces.Dialect): supports_comments = False inline_comments = False use_setinputsizes = False + supports_statement_cache = True # the first value we'd get for an autoincrement # column. @@ -215,6 +217,7 @@ class DefaultDialect(interfaces.Dialect): CACHE_MISS = CACHE_MISS CACHING_DISABLED = CACHING_DISABLED NO_CACHE_KEY = NO_CACHE_KEY + NO_DIALECT_SUPPORT = NO_DIALECT_SUPPORT @util.deprecated_params( convert_unicode=( @@ -320,6 +323,13 @@ class DefaultDialect(interfaces.Dialect): self._decoder = processors.to_unicode_processor_factory(self.encoding) @util.memoized_property + def _supports_statement_cache(self): + return ( + self.__class__.__dict__.get("supports_statement_cache", False) + is True + ) + + @util.memoized_property def _type_memos(self): return weakref.WeakKeyDictionary() @@ -771,6 +781,8 @@ class StrCompileDialect(DefaultDialect): type_compiler = compiler.StrSQLTypeCompiler preparer = compiler.IdentifierPreparer + supports_statement_cache = True + supports_sequences = True sequences_optional = True preexecute_autoincrement_sequences = False @@ -1137,6 +1149,12 @@ class DefaultExecutionContext(interfaces.ExecutionContext): return "generated in %.5fs" % (now - self.compiled._gen_time,) elif ch is CACHING_DISABLED: return "caching disabled %.5fs" % (now - self.compiled._gen_time,) + elif ch is NO_DIALECT_SUPPORT: + return "dialect %s+%s does not support caching %.5fs" % ( + self.dialect.name, + self.dialect.driver, + now - self.compiled._gen_time, + ) else: return "unknown" diff --git a/lib/sqlalchemy/engine/interfaces.py b/lib/sqlalchemy/engine/interfaces.py index 24e0e5b0d..5e6cc524e 100644 --- a/lib/sqlalchemy/engine/interfaces.py +++ b/lib/sqlalchemy/engine/interfaces.py @@ -152,6 +152,24 @@ class Dialect(object): _has_events = False + 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. + + .. versionadded:: 1.4.5 + + .. seealso:: + + :ref:`engine_thirdparty_caching` + + """ + def create_connect_args(self, url): """Build DB-API compatible connection arguments. diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py index b64427d51..7a27690b8 100644 --- a/lib/sqlalchemy/sql/elements.py +++ b/lib/sqlalchemy/sql/elements.py @@ -514,7 +514,7 @@ class ClauseElement( schema_translate_map=None, **kw ): - if compiled_cache is not None: + if compiled_cache is not None and dialect._supports_statement_cache: elem_cache_key = self._generate_cache_key() else: elem_cache_key = None @@ -553,11 +553,13 @@ class ClauseElement( schema_translate_map=schema_translate_map, **kw ) - cache_hit = ( - dialect.CACHING_DISABLED - if compiled_cache is None - else dialect.NO_CACHE_KEY - ) + + if not dialect._supports_statement_cache: + cache_hit = dialect.NO_DIALECT_SUPPORT + elif compiled_cache is None: + cache_hit = dialect.CACHING_DISABLED + else: + cache_hit = dialect.NO_CACHE_KEY return compiled_sql, extracted_params, cache_hit @@ -1429,6 +1431,34 @@ class BindParameter(roles.InElementRole, ColumnElement): else: return self.value + def render_literal_execute(self): + """Produce a copy of this bound parameter that will enable the + :paramref:`_sql.BindParameter.literal_execute` flag. + + The :paramref:`_sql.BindParameter.literal_execute` flag will + have the effect of the parameter rendered in the compiled SQL + string using ``[POSTCOMPILE]`` form, which is a special form that + is converted to be a rendering of the literal value of the parameter + at SQL execution time. The rationale is to support caching + of SQL statement strings that can embed per-statement literal values, + such as LIMIT and OFFSET parameters, in the final SQL string that + is passed to the DBAPI. Dialects in particular may want to use + this method within custom compilation schemes. + + .. versionadded:: 1.4.5 + + .. seealso:: + + :ref:`engine_thirdparty_caching` + + """ + return self.__class__( + self.key, + self.value, + type_=self.type, + literal_execute=True, + ) + def _with_binary_element_type(self, type_): c = ClauseElement._clone(self) c.type = type_ diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py index 189deec41..a2e5780f8 100644 --- a/lib/sqlalchemy/sql/selectable.py +++ b/lib/sqlalchemy/sql/selectable.py @@ -69,14 +69,6 @@ class _OffsetLimitParam(BindParameter): def _limit_offset_value(self): return self.effective_value - def _render_literal_execute(self): - return _OffsetLimitParam( - self.key, - self.value, - type_=self.type, - literal_execute=True, - ) - @util.deprecated( "1.4", |
