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PG16: Fix join recursion

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The initial approach to mark EquivalenceMember as derived had some
loopholes still leading to infinite recursion with certain join
conditions.
This commit is contained in:
Sven Klemm 2023-11-06 09:03:43 +01:00 committed by Sven Klemm
parent c34fd0b06c
commit e93b5fa657
3 changed files with 30 additions and 29 deletions
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44
tsl/src/nodes/decompress_chunk/decompress_chunk.c
View File

@ -1416,22 +1416,6 @@ create_var_for_compressed_equivalence_member(Var *var, const EMCreationContext *
return NULL;
}
#if PG16_GE
static EquivalenceMember *
find_em_for_relid(EquivalenceClass *ec, Index relid)
{
ListCell *lc;
foreach (lc, ec->ec_members)
{
EquivalenceMember *em = lfirst_node(EquivalenceMember, lc);
if (bms_is_member(relid, em->em_relids) && bms_num_members(em->em_relids) == 1)
return em;
}
return NULL;
}
#endif
/* This function is inspired by the Postgres add_child_rel_equivalences. */
static bool
add_segmentby_to_equivalence_class(PlannerInfo *root, EquivalenceClass *cur_ec,
@ -1545,22 +1529,24 @@ add_segmentby_to_equivalence_class(PlannerInfo *root, EquivalenceClass *cur_ec,
lappend(compressed_fdw_private->compressed_ec_em_pairs, list_make2(cur_ec, em));
#if PG16_GE
EquivalenceMember *ht_em = find_em_for_relid(cur_ec, info->ht_rel->relid);
/* Record EquivalenceMember for the compressed chunk as derived to prevent
* infinite recursion.
*/
if (ht_em && ht_em->em_jdomain)
foreach (lc, cur_ec->ec_members)
{
int i = -1;
while ((i = bms_next_member(ht_em->em_jdomain->jd_relids, i)) >= 0)
{
RestrictInfo *d = make_simple_restrictinfo_compat(root, em->em_expr);
d->parent_ec = cur_ec;
d->left_em = find_em_for_relid(cur_ec, i);
if (!d->left_em)
continue;
d->right_em = em;
cur_ec->ec_derives = lappend(cur_ec->ec_derives, d);
}
EquivalenceMember *p_em = lfirst_node(EquivalenceMember, lc);
/* Assume non-child member are at the beginning */
if (p_em->em_is_child)
break;
RestrictInfo *d = make_simple_restrictinfo_compat(root, p_em->em_expr);
d->parent_ec = cur_ec;
d->left_em = p_em;
d->right_em = em;
cur_ec->ec_derives = lappend(cur_ec->ec_derives, d);
}
#endif
return true;

9
tsl/test/shared/expected/decompress_join.out
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@ -60,3 +60,12 @@ SELECT * FROM partial_join m1 INNER JOIN partial_join m2 ON m1.device = m2.devic
(4 rows)
DROP TABLE partial_join;
-- This resulted in a recursion in the join planner code on PG16
SELECT * FROM metrics_tstz as m
INNER JOIN metrics_space as ms on (true)
INNER JOIN metrics_space_compressed as msc on (true)
WHERE CASE WHEN m.device_id is not NULL and ms.v2 is not NULL THEN NULL::int2 end = msc.device_id;
time | device_id | v1 | v2 | time | device_id | v0 | v1 | v2 | v3 | time | device_id | v0 | v1 | v2 | v3
------+-----------+----+----+------+-----------+----+----+----+----+------+-----------+----+----+----+----
(0 rows)

6
tsl/test/shared/sql/decompress_join.sql
View File

@ -35,3 +35,9 @@ SELECT * FROM partial_join m1 INNER JOIN partial_join m2 ON m1.device = m2.devic
DROP TABLE partial_join;
-- This resulted in a recursion in the join planner code on PG16
SELECT * FROM metrics_tstz as m
INNER JOIN metrics_space as ms on (true)
INNER JOIN metrics_space_compressed as msc on (true)
WHERE CASE WHEN m.device_id is not NULL and ms.v2 is not NULL THEN NULL::int2 end = msc.device_id;