diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c new file mode 100644 index adc9e76..f3a4d3b --- a/src/backend/rewrite/rewriteHandler.c +++ b/src/backend/rewrite/rewriteHandler.c @@ -3872,9 +3872,13 @@ rewriteTargetView(Query *parsetree, Rela * orig_rt_length is the length of the originating query's rtable, for product * queries created by fireRules(), and 0 otherwise. This is used to skip any * already-processed VALUES RTEs from the original query. + * + * num_ctes_processed is the number of CTEs at the end of the query's cteList + * that have already been rewritten, and must not be rewritten again. */ static List * -RewriteQuery(Query *parsetree, List *rewrite_events, int orig_rt_length) +RewriteQuery(Query *parsetree, List *rewrite_events, int orig_rt_length, + int num_ctes_processed) { CmdType event = parsetree->commandType; bool instead = false; @@ -3883,22 +3887,36 @@ RewriteQuery(Query *parsetree, List *rew Query *qual_product = NULL; List *rewritten = NIL; ListCell *lc1; + int i; /* * First, recursively process any insert/update/delete/merge statements in * WITH clauses. (We have to do this first because the WITH clauses may * get copied into rule actions below.) + * + * Any new WITH clauses from rule actions are processed when we recurse + * into product queries below. However, when recursing, we must take care + * to avoid rewriting a CTE query more than once (because expanding + * generated columns in the targetlist more than once would fail). Since + * new CTEs from product queries are added to the start of the list (see + * rewriteRuleAction), we just skip the last num_ctes_processed items. */ + i = 0; foreach(lc1, parsetree->cteList) { CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc1); Query *ctequery = castNode(Query, cte->ctequery); List *newstuff; + /* Skip already-processed CTEs at the end of the list */ + i++; + if (i > list_length(parsetree->cteList) - num_ctes_processed) + break; + if (ctequery->commandType == CMD_SELECT) continue; - newstuff = RewriteQuery(ctequery, rewrite_events, 0); + newstuff = RewriteQuery(ctequery, rewrite_events, 0, 0); /* * Currently we can only handle unconditional, single-statement DO @@ -3958,6 +3976,7 @@ RewriteQuery(Query *parsetree, List *rew errmsg("multi-statement DO INSTEAD rules are not supported for data-modifying statements in WITH"))); } } + num_ctes_processed = list_length(parsetree->cteList); /* * If the statement is an insert, update, delete, or merge, adjust its @@ -4289,7 +4308,8 @@ RewriteQuery(Query *parsetree, List *rew newstuff = RewriteQuery(pt, rewrite_events, pt == parsetree ? orig_rt_length : - product_orig_rt_length); + product_orig_rt_length, + num_ctes_processed); rewritten = list_concat(rewritten, newstuff); } @@ -4564,7 +4584,7 @@ QueryRewrite(Query *parsetree) * * Apply all non-SELECT rules possibly getting 0 or many queries */ - querylist = RewriteQuery(parsetree, NIL, 0); + querylist = RewriteQuery(parsetree, NIL, 0, 0); /* * Step 2 diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out new file mode 100644 index f4caedf..e71c3cc --- a/src/test/regress/expected/with.out +++ b/src/test/regress/expected/with.out @@ -2872,6 +2872,19 @@ SELECT * FROM bug6051_3; --- (0 rows) +-- check that recursive CTE processing doesn't rewrite a CTE more than once +-- (must not try to expand IDENTITY column more than once) +CREATE TEMP TABLE id_alw (i int GENERATED ALWAYS AS IDENTITY); +CREATE TEMP TABLE id_alw_base (i int); +CREATE TEMP VIEW id_alw_view AS SELECT * FROM id_alw_base; +WITH t_cte AS (INSERT INTO id_alw DEFAULT VALUES RETURNING i) + INSERT INTO id_alw_view SELECT i FROM t_cte; +SELECT * from id_alw_view; + i +--- + 1 +(1 row) + -- check case where CTE reference is removed due to optimization EXPLAIN (VERBOSE, COSTS OFF) SELECT q1 FROM diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql new file mode 100644 index cd25a5e..efeb977 --- a/src/test/regress/sql/with.sql +++ b/src/test/regress/sql/with.sql @@ -1360,6 +1360,17 @@ COMMIT; SELECT * FROM bug6051_3; +-- check that recursive CTE processing doesn't rewrite a CTE more than once +-- (must not try to expand IDENTITY column more than once) +CREATE TEMP TABLE id_alw (i int GENERATED ALWAYS AS IDENTITY); +CREATE TEMP TABLE id_alw_base (i int); +CREATE TEMP VIEW id_alw_view AS SELECT * FROM id_alw_base; + +WITH t_cte AS (INSERT INTO id_alw DEFAULT VALUES RETURNING i) + INSERT INTO id_alw_view SELECT i FROM t_cte; + +SELECT * from id_alw_view; + -- check case where CTE reference is removed due to optimization EXPLAIN (VERBOSE, COSTS OFF) SELECT q1 FROM