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bpo-43258: Prevent needless allocation of sqlite3 aggregate context for empty queries #24569

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Merged
merged 3 commits into from
Feb 19, 2021
Merged

bpo-43258: Prevent needless allocation of sqlite3 aggregate context for empty queries #24569

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3470ce0
Prevent needless memory allocations of SQLite aggregate context
Feb 18, 2021
b7dd8c2
Handle aggregate queries with no hits
Feb 18, 2021
9722ea9
Add NEWS
Feb 18, 2021
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5 changes: 5 additions & 0 deletions Lib/sqlite3/test/userfunctions.py
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Original file line number Diff line number Diff line change
Expand Up @@ -429,6 +429,11 @@ def test_aggr_check_aggr_sum(self):
val = cur.fetchone()[0]
self.assertEqual(val, 60)

def test_aggr_no_match(self):
cur = self.con.execute("select mysum(i) from (select 1 as i) where i == 0")
val = cur.fetchone()[0]
self.assertIsNone(val)

class AuthorizerTests(unittest.TestCase):
@staticmethod
def authorizer_cb(action, arg1, arg2, dbname, source):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2021-02-18-23-30-52.bpo-43258.LeU-q8.rst
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@@ -0,0 +1,2 @@
Prevent needless allocation of :mod:`sqlite3` aggregate function context
when no rows match an aggregate query. Patch by Erlend E. Aasland.
8 changes: 6 additions & 2 deletions Modules/_sqlite/connection.c
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Expand Up @@ -708,8 +708,12 @@ void _pysqlite_final_callback(sqlite3_context* context)

threadstate = PyGILState_Ensure();

aggregate_instance = (PyObject**)sqlite3_aggregate_context(context, sizeof(PyObject*));
if (!*aggregate_instance) {
aggregate_instance = (PyObject**)sqlite3_aggregate_context(context, 0);
if (aggregate_instance == NULL) {
/* No rows matched the query; the step handler was never called. */
goto error;
}
else if (!*aggregate_instance) {
/* this branch is executed if there was an exception in the aggregate's
* __init__ */

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