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Allow subqueries in LIMIT/OFFSET

pull/3746/head
Philip Dubé 2020-04-10 02:37:36 +00:00
parent 132efdbc56
commit 8c959fd6f9
4 changed files with 56 additions and 15 deletions
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21
src/backend/distributed/planner/distributed_planner.c
View File

@ -258,8 +258,27 @@ distributed_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
planContext.plan = standard_planner(planContext.query,
planContext.cursorOptions,
planContext.boundParams);
if (needsDistributedPlanning)
{
/*
* standard_planner rewrites simple queries like 'select 10' to PARAM_EXEC nodes,
* which we're unable to handle. Meanwhile we only optimize rewrites to Const.
* So deoptimize non-Const LIMIT/OFFSET, standard_planner will handle it again later.
*/
if (planContext.query->limitCount &&
!IsA(planContext.query->limitCount, Const))
{
planContext.query->limitCount = planContext.originalQuery->limitCount;
}
if (planContext.query->limitOffset &&
!IsA(planContext.query->limitOffset, Const))
{
planContext.query->limitOffset =
planContext.originalQuery->limitOffset;
}
result = PlanDistributedStmt(&planContext, rteIdCounter);
}
else if ((result = TryToDelegateFunctionCall(&planContext)) == NULL)
@ -806,7 +825,7 @@ InlineCtesAndCreateDistributedPlannedStmt(uint64 planId,
/* after inlining, we shouldn't have any inlinable CTEs */
Assert(!QueryTreeContainsInlinableCTE(copyOfOriginalQuery));
#if PG_VERSION_NUM < PG_VERSION_12
#if PG_VERSION_NUM < PG_VERSION_12
Query *query = planContext->query;
/*

12
src/backend/distributed/planner/multi_logical_planner.c
View File

@ -1013,18 +1013,6 @@ DeferErrorIfQueryNotSupported(Query *queryTree)
errorHint = filterHint;
}
if (FindNodeCheck((Node *) queryTree->limitCount, IsNodeSubquery))
{
preconditionsSatisfied = false;
errorMessage = "subquery in LIMIT is not supported in multi-shard queries";
}
if (FindNodeCheck((Node *) queryTree->limitOffset, IsNodeSubquery))
{
preconditionsSatisfied = false;
errorMessage = "subquery in OFFSET is not supported in multi-shard queries";
}
/* finally check and error out if not satisfied */
if (!preconditionsSatisfied)
{

36
src/test/regress/expected/multi_limit_clause.out
View File

@ -553,8 +553,40 @@ SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT 10 OFFSET my_limi
DROP FUNCTION my_limit();
-- subqueries should error out
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT (SELECT min(l_linenumber) FROM lineitem_hash) OFFSET (SELECT (count(*)/2)::int FROM lineitem_hash);
l_orderkey
---------------------------------------------------------------------
8997
(1 row)
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT (SELECT 10);
ERROR: subquery in LIMIT is not supported in multi-shard queries
l_orderkey
---------------------------------------------------------------------
1
1
1
1
1
1
2
3
3
3
(10 rows)
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT 10 OFFSET (SELECT 10);
ERROR: subquery in OFFSET is not supported in multi-shard queries
l_orderkey
---------------------------------------------------------------------
3
3
3
4
5
5
5
6
7
7
(10 rows)
DROP TABLE lineitem_hash;

2
src/test/regress/sql/multi_limit_clause.sql
View File

@ -237,6 +237,8 @@ SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT 10 OFFSET my_limi
DROP FUNCTION my_limit();
-- subqueries should error out
SELECT min(l_linenumber) FROM lineitem;
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT (SELECT min(l_linenumber) FROM lineitem) OFFSET (SELECT (count(*)/2)::int FROM lineitem_hash);
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT (SELECT 10);
SELECT l_orderkey FROM lineitem_hash ORDER BY l_orderkey LIMIT 10 OFFSET (SELECT 10);