swh.core.db.db_utils module

swh.core.db.db_utils.stored_procedure(stored_proc)[source]

decorator to execute remote stored procedure, specified as argument

Generally, the body of the decorated function should be empty. If it is not, the stored procedure will be executed first; the function body then.

swh.core.db.db_utils.jsonize(value)[source]

Convert a value to a psycopg2 JSON object if necessary

swh.core.db.db_utils.connect_to_conninfo(db_or_conninfo: Union[str, psycopg2.extensions.connection]) → psycopg2.extensions.connection[source]

Connect to the database passed in argument

Parameters

db_or_conninfo – A database connection, or a database connection info string

Returns

a connected database handle

Raises

psycopg2.Error if the database doesn't exist –

swh.core.db.db_utils.swh_db_version(db_or_conninfo: Union[str, psycopg2.extensions.connection]) → Optional[int][source]

Retrieve the swh version of the database.

If the database is not initialized, this logs a warning and returns None.

Parameters

db_or_conninfo – A database connection, or a database connection info string

Returns

Either the version of the database, or None if it couldn’t be detected

swh.core.db.db_utils.swh_db_flavor(db_or_conninfo: Union[str, psycopg2.extensions.connection]) → Optional[str][source]

Retrieve the swh flavor of the database.

If the database is not initialized, or the database doesn’t support flavors, this returns None.

Parameters

db_or_conninfo – A database connection, or a database connection info string

Returns

The flavor of the database, or None if it could not be detected.

swh.core.db.db_utils.execute_values_generator(cur, sql, argslist, template=None, page_size=100)[source]

Execute a statement using SQL VALUES with a sequence of parameters. Rows returned by the query are returned through a generator. You need to consume the generator for the queries to be executed!

Parameters

  • cur – the cursor to use to execute the query.

  • sql – the query to execute. It must contain a single %s placeholder, which will be replaced by a VALUES list. Example: "INSERT INTO mytable (id, f1, f2) VALUES %s".

  • argslist – sequence of sequences or dictionaries with the arguments to send to the query. The type and content must be consistent with template.

  • template –

    the snippet to merge to every item in argslist to compose the query.

    • If the argslist items are sequences it should contain positional placeholders (e.g. "(%s, %s, %s)", or "(%s, %s, 42)” if there are constants value…).

    • If the argslist items are mappings it should contain named placeholders (e.g. "(%(id)s, %(f1)s, 42)").

    If not specified, assume the arguments are sequence and use a simple positional template (i.e. (%s, %s, ...)), with the number of placeholders sniffed by the first element in argslist.

  • page_size – maximum number of argslist items to include in every statement. If there are more items the function will execute more than one statement.

  • yield_from_cur – Whether to yield results from the cursor in this function directly.

After the execution of the function the cursor.rowcount property will not contain a total result.