mysql and postgresql backends get_last_insert_id() do extra queries
|Reported by:||anonymous||Owned by:||Adrian Holovaty|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
Cursor Attribute .lastrowid This read-only attribute provides the rowid of the last modified row (most databases return a rowid only when a single INSERT operation is performed). If the operation does not set a rowid or if the database does not support rowids, this attribute should be set to None. The semantics of .lastrowid are undefined in case the last executed statement modified more than one row, e.g. when using INSERT with .executemany(). Warning Message: "DB-API extension cursor.lastrowid used"
While this is an extension, it is supported by both MySQLdb and psycopg (including version 1). Therefore, it is only necessary in base.py to do this:
def get_last_insert_id(cursor, table_name, pk_name): return cursor.lastrowid
The sqlite3 backend already does this, in fact.
I've been testing the above change with MySQLdb for awhile and it works fine. I have not tried it with pyscopg1, but judging from the source code, it should work: http://initd.org/tracker/psycopg/browser/psycopg1/trunk/cursor.c (look for lastrowid defined on the cursor object).