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Merge pull request #1106 from citusdata/error_out_cte_with_modify 

Error out on CTEs with data modifying statement
pull/1095/head
Burak Yücesoy 2017-01-10 09:35:46 +02:00 committed by GitHub
parent 8b3dc1f974 59d3d05bc4
commit 2a13f23176
3 changed files with 93 additions and 3 deletions
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45
src/backend/distributed/planner/multi_router_planner.c
View File

@ -127,7 +127,7 @@ static void ErrorIfInsertPartitionColumnDoesNotMatchSelect(Query *query,
Oid *
selectPartitionColumnTableId);
static void AddUninstantiatedEqualityQual(Query *query, Var *targetPartitionColumnVar);
static void ErrorIfQueryHasModifyingCTE(Query *queryTree);
/*
* MultiRouterPlanCreate creates a multi plan for the queries
@ -202,8 +202,7 @@ CreateSingleTaskRouterPlan(Query *originalQuery, Query *query,
}
else
{
Assert(commandType == CMD_SELECT);
ErrorIfQueryHasModifyingCTE(query);
task = RouterSelectTask(originalQuery, restrictionContext, &placementList);
}
@ -2850,3 +2849,43 @@ InstantiatePartitionQual(Node *node, void *context)
return expression_tree_mutator(node, InstantiatePartitionQual, context);
}
/*
* ErrorIfQueryHasModifyingCTE checks if the query contains modifying common table
* expressions and errors out if it does.
*/
static void
ErrorIfQueryHasModifyingCTE(Query *queryTree)
{
ListCell *cteCell = NULL;
Assert(queryTree->commandType == CMD_SELECT);
/* we do not need to do anything if there are no CTEs */
if (queryTree->cteList == NIL)
{
return;
}
foreach(cteCell, queryTree->cteList)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(cteCell);
Query *cteQuery = (Query *) cte->ctequery;
/*
* Here we only check for command type of top level query. Normally there can be
* nested CTE, however PostgreSQL dictates that data-modifying statements must
* be at top level of CTE. Therefore it is OK to just check for top level.
* Similarly, we do not need to check for subqueries.
*/
if (cteQuery->commandType != CMD_SELECT)
{
ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot perform distributed planning for the given "
"modification"),
errdetail("Data-modifying statements are not supported in "
"the WITH clauses of distributed queries.")));
}
}
}

28
src/test/regress/expected/multi_router_planner.out
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@ -439,6 +439,34 @@ DEBUG: predicate pruning for shardId 840004
DEBUG: predicate pruning for shardId 840005
ERROR: cannot perform distributed planning on this query
DETAIL: Complex table expressions are currently unsupported
-- CTE with queries other than SELECT is not supported
WITH new_article AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM new_article;
ERROR: cannot perform distributed planning for the given modification
DETAIL: Data-modifying statements are not supported in the WITH clauses of distributed queries.
-- Modifying statement in nested CTE case is covered by PostgreSQL itself
WITH new_article AS (
WITH nested_cte AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM nested_cte
)
SELECT * FROM new_article;
ERROR: WITH clause containing a data-modifying statement must be at the top level
LINE 2: WITH nested_cte AS (
^
-- Modifying statement in a CTE in subquwey is also covered by PostgreSQL
SELECT * FROM (
WITH new_article AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM new_article
) AS subquery_cte;
ERROR: WITH clause containing a data-modifying statement must be at the top level
LINE 2: WITH new_article AS (
^
-- grouping sets are supported on single shard
SELECT
id, substring(title, 2, 1) AS subtitle, count(*)

23
src/test/regress/sql/multi_router_planner.sql
View File

@ -226,6 +226,29 @@ WITH RECURSIVE hierarchy as (
ce.company_id = 2))
SELECT * FROM hierarchy WHERE LEVEL <= 2;
-- CTE with queries other than SELECT is not supported
WITH new_article AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM new_article;
-- Modifying statement in nested CTE case is covered by PostgreSQL itself
WITH new_article AS (
WITH nested_cte AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM nested_cte
)
SELECT * FROM new_article;
-- Modifying statement in a CTE in subquwey is also covered by PostgreSQL
SELECT * FROM (
WITH new_article AS (
INSERT INTO articles_hash VALUES (1, 1, 'arsenous', 9572) RETURNING *
)
SELECT * FROM new_article
) AS subquery_cte;
-- grouping sets are supported on single shard
SELECT
id, substring(title, 2, 1) AS subtitle, count(*)