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prefect.server.database.configurations

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Classes

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ConnectionTracker

A test utility which tracks the connections given out by a connection pool, to make it easy to see which connections are currently checked out and open. Methods:

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clear 

clear(self) -> None

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on_close 

on_close(self, adapted_connection: AdaptedConnection, connection_record: ConnectionPoolEntry) -> None

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on_close_detached 

on_close_detached(self, adapted_connection: AdaptedConnection) -> None

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on_connect 

on_connect(self, adapted_connection: AdaptedConnection, connection_record: ConnectionPoolEntry) -> None

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track_pool 

track_pool(self, pool: sa.pool.Pool) -> None

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BaseDatabaseConfiguration

Abstract base class used to inject database connection configuration into Prefect. This configuration is responsible for defining how Prefect REST API creates and manages database connections and sessions. Methods:

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begin_transaction 

begin_transaction(self, session: AsyncSession, with_for_update: bool = False) -> AbstractAsyncContextManager[AsyncSessionTransaction]
Enter a transaction for a session

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create_db 

create_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Create the database

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drop_db 

drop_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Drop the database

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engine 

engine(self) -> AsyncEngine
Returns a SqlAlchemy engine

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is_inmemory 

is_inmemory(self) -> bool
Returns true if database is run in memory

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session 

session(self, engine: AsyncEngine) -> AsyncSession
Retrieves a SQLAlchemy session for an engine.

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unique_key 

unique_key(self) -> tuple[Hashable, ...]
Returns a key used to determine whether to instantiate a new DB interface.

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AsyncPostgresConfiguration

Methods:

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begin_transaction 

begin_transaction(self, session: AsyncSession, with_for_update: bool = False) -> AsyncGenerator[AsyncSessionTransaction, None]

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begin_transaction 

begin_transaction(self, session: AsyncSession, with_for_update: bool = False) -> AbstractAsyncContextManager[AsyncSessionTransaction]
Enter a transaction for a session

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create_db 

create_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Create the database

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create_db 

create_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Create the database

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drop_db 

drop_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Drop the database

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drop_db 

drop_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Drop the database

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engine 

engine(self) -> AsyncEngine
Retrieves an async SQLAlchemy engine. Args:
  • connection_url: The database connection string. Defaults to self.connection_url
  • echo: Whether to echo SQL sent to the database. Defaults to self.echo
  • timeout: The database statement timeout, in seconds. Defaults to self.timeout
Returns:
  • a SQLAlchemy engine

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engine 

engine(self) -> AsyncEngine
Returns a SqlAlchemy engine

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is_inmemory 

is_inmemory(self) -> bool
Returns true if database is run in memory

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is_inmemory 

is_inmemory(self) -> bool
Returns true if database is run in memory

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schedule_engine_disposal 

schedule_engine_disposal(self, cache_key: _EngineCacheKey) -> None
Dispose of an engine once the event loop is closing. See caveats at add_event_loop_shutdown_callback. We attempted to lazily clean up old engines when new engines are created, but if the loop the engine is attached to is already closed then the connections cannot be cleaned up properly and warnings are displayed. Engine disposal should only be important when running the application ephemerally. Notably, this is an issue in our tests where many short-lived event loops and engines are created which can consume all of the available database connection slots. Users operating at a scale where connection limits are encountered should be encouraged to use a standalone server.

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session 

session(self, engine: AsyncEngine) -> AsyncSession
Retrieves a SQLAlchemy session for an engine. Args:
  • engine: a sqlalchemy engine

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session 

session(self, engine: AsyncEngine) -> AsyncSession
Retrieves a SQLAlchemy session for an engine.

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unique_key 

unique_key(self) -> tuple[Hashable, ...]
Returns a key used to determine whether to instantiate a new DB interface.

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AioSqliteConfiguration

Methods:

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begin_sqlite_conn 

begin_sqlite_conn(self, conn: aiosqlite.AsyncAdapt_aiosqlite_connection) -> None

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begin_sqlite_stmt 

begin_sqlite_stmt(self, conn: sa.Connection) -> None

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begin_transaction 

begin_transaction(self, session: AsyncSession, with_for_update: bool = False) -> AsyncGenerator[AsyncSessionTransaction, None]

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begin_transaction 

begin_transaction(self, session: AsyncSession, with_for_update: bool = False) -> AbstractAsyncContextManager[AsyncSessionTransaction]
Enter a transaction for a session

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create_db 

create_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Create the database

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create_db 

create_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Create the database

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drop_db 

drop_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Drop the database

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drop_db 

drop_db(self, connection: AsyncConnection, base_metadata: sa.MetaData) -> None
Drop the database

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engine 

engine(self) -> AsyncEngine
Retrieves an async SQLAlchemy engine. Args:
  • connection_url: The database connection string. Defaults to self.connection_url
  • echo: Whether to echo SQL sent to the database. Defaults to self.echo
  • timeout: The database statement timeout, in seconds. Defaults to self.timeout
Returns:
  • a SQLAlchemy engine

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engine 

engine(self) -> AsyncEngine
Returns a SqlAlchemy engine

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is_inmemory 

is_inmemory(self) -> bool
Returns true if database is run in memory

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is_inmemory 

is_inmemory(self) -> bool
Returns true if database is run in memory

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schedule_engine_disposal 

schedule_engine_disposal(self, cache_key: _EngineCacheKey) -> None
Dispose of an engine once the event loop is closing. See caveats at add_event_loop_shutdown_callback. We attempted to lazily clean up old engines when new engines are created, but if the loop the engine is attached to is already closed then the connections cannot be cleaned up properly and warnings are displayed. Engine disposal should only be important when running the application ephemerally. Notably, this is an issue in our tests where many short-lived event loops and engines are created which can consume all of the available database connection slots. Users operating at a scale where connection limits are encountered should be encouraged to use a standalone server.

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session 

session(self, engine: AsyncEngine) -> AsyncSession
Retrieves a SQLAlchemy session for an engine. Args:
  • engine: a sqlalchemy engine

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session 

session(self, engine: AsyncEngine) -> AsyncSession
Retrieves a SQLAlchemy session for an engine.

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setup_sqlite 

setup_sqlite(self, conn: DBAPIConnection, record: ConnectionPoolEntry) -> None
Issue PRAGMA statements to SQLITE on connect. PRAGMAs only last for the duration of the connection. See https://www.sqlite.org/pragma.html for more info.

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unique_key 

unique_key(self) -> tuple[Hashable, ...]
Returns a key used to determine whether to instantiate a new DB interface.