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Merge pull request #2105 from citusdata/fix_null_access 

Citus should not consider subqueries that are removed by PostgreSQL planner
pull/2120/head^2
Önder Kalacı 2018-04-21 04:23:47 +03:00 committed by GitHub
parent b0b130f064 814f0e3acc
commit 6c6cddff04
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 209 additions and 1 deletions
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18
src/backend/distributed/planner/relation_restriction_equivalence.c
View File

@ -1179,6 +1179,22 @@ AddRteSubqueryToAttributeEquivalenceClass(AttributeEquivalenceClass
TargetEntry *subqueryTargetEntry = NULL;
Query *targetSubquery = GetTargetSubquery(root, rangeTableEntry, varToBeAdded);
/*
* We might not always get the subquery because the subquery might be a
* referencing to RELOPT_DEADREL such that the corresponding join is
* removed via join_is_removable().
*
* Returning here implies that PostgreSQL doesn't need to plan the
* subquery because it doesn't contribute to the query result at all.
* Since the relations in the subquery does not appear in the query
* plan as well, Citus would simply ignore the subquery and treat that
* as a safe-to-pushdown subquery.
*/
if (targetSubquery == NULL)
{
return;
}
subqueryTargetEntry = get_tle_by_resno(targetSubquery->targetList,
varToBeAdded->varattno);
@ -1252,7 +1268,7 @@ GetTargetSubquery(PlannerInfo *root, RangeTblEntry *rangeTableEntry, Var *varToB
{
RelOptInfo *baseRelOptInfo = find_base_rel(root, varToBeAdded->varno);
/* If the targetSubquery hasn't been planned yet, we have to punt */
/* If the targetSubquery was not planned, we have to punt */
if (baseRelOptInfo->subroot == NULL)
{
return NULL;

107
src/test/regress/expected/multi_subquery_misc.out
View File

@ -276,5 +276,112 @@ ERROR: could not create distributed plan
DETAIL: Possibly this is caused by the use of parameters in SQL functions, which is not supported in Citus.
HINT: Consider using PL/pgSQL functions instead.
CONTEXT: SQL function "sql_subquery_test" statement 1
-- the joins are actually removed since they are
-- not needed by PostgreSQL planner (e.g., target list
-- doesn't contain anything from there)
-- but Citus can still pushdown this query
SELECT
t1.user_id, count(*)
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
user_id
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
GROUP BY 1
ORDER BY 2 DESC;
user_id | count
---------+-------
5 | 676
4 | 529
2 | 324
3 | 289
6 | 100
1 | 49
(6 rows)
-- the joins are actually removed since they are
-- not needed by PostgreSQL planner (e.g., target list
-- doesn't contain anything from there)
-- but Citus can still plan this query even though the query
-- is not safe to pushdown
SELECT
t1.user_id, count(*)
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
value_2
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
GROUP BY 1
ORDER BY 2 DESC;
user_id | count
---------+-------
5 | 676
4 | 529
2 | 324
3 | 289
6 | 100
1 | 49
(6 rows)
-- Similar to the above queries, but
-- this time the joins are not removed because
-- target list contains all the entries
SELECT
*
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
user_id
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
ORDER BY 1 DESC, 2 DESC, 3 DESC, 4 DESC, 5 DESC, 6 DESC, 7 DESC, 8 DESC
LIMIT 5;
user_id | time | value_1 | value_2 | value_3 | value_4 | user_id | user_id
---------+---------------------------------+---------+---------+---------+---------+---------+---------
6 | Thu Nov 23 14:43:18.024104 2017 | 3 | 2 | 5 | | 6 | 6
6 | Thu Nov 23 14:43:18.024104 2017 | 3 | 2 | 5 | | 6 | 6
6 | Thu Nov 23 14:43:18.024104 2017 | 3 | 2 | 5 | | 6 | 6
6 | Thu Nov 23 14:43:18.024104 2017 | 3 | 2 | 5 | | 6 | 6
6 | Thu Nov 23 14:43:18.024104 2017 | 3 | 2 | 5 | | 6 | 6
(5 rows)
DROP FUNCTION plpgsql_subquery_test(int, int);
DROP FUNCTION sql_subquery_test(int, int);

85
src/test/regress/sql/multi_subquery_misc.sql
View File

@ -151,5 +151,90 @@ $$ LANGUAGE SQL;
-- should error out
SELECT sql_subquery_test(1,1);
-- the joins are actually removed since they are
-- not needed by PostgreSQL planner (e.g., target list
-- doesn't contain anything from there)
-- but Citus can still pushdown this query
SELECT
t1.user_id, count(*)
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
user_id
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
GROUP BY 1
ORDER BY 2 DESC;
-- the joins are actually removed since they are
-- not needed by PostgreSQL planner (e.g., target list
-- doesn't contain anything from there)
-- but Citus can still plan this query even though the query
-- is not safe to pushdown
SELECT
t1.user_id, count(*)
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
value_2
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
GROUP BY 1
ORDER BY 2 DESC;
-- Similar to the above queries, but
-- this time the joins are not removed because
-- target list contains all the entries
SELECT
*
FROM users_table t1
LEFT JOIN (
SELECT
user_id
FROM
users_table
UNION
SELECT
user_id
FROM
events_table
) t2 ON t1.user_id = t2.user_id
INNER JOIN (
SELECT
user_id
FROM
users_table
) t3 ON t1.user_id = t3.user_id
ORDER BY 1 DESC, 2 DESC, 3 DESC, 4 DESC, 5 DESC, 6 DESC, 7 DESC, 8 DESC
LIMIT 5;
DROP FUNCTION plpgsql_subquery_test(int, int);
DROP FUNCTION sql_subquery_test(int, int);