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SEARCH and CYCLE clauses

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This adds the SQL standard feature that adds the SEARCH and CYCLE
clauses to recursive queries to be able to do produce breadth- or
depth-first search orders and detect cycles.  These clauses can be
rewritten into queries using existing syntax, and that is what this
patch does in the rewriter.

Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2021-02-01 13:54:59 +01:00
parent bb513b364b
commit 3696a600e2
28 changed files with 2301 additions and 33 deletions
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17
src/backend/parser/parse_target.c
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@@ -399,8 +399,23 @@ markTargetListOrigin(ParseState *pstate, TargetEntry *tle,
{
CommonTableExpr *cte = GetCTEForRTE(pstate, rte, netlevelsup);
TargetEntry *ste;
List *tl = GetCTETargetList(cte);
int extra_cols = 0;
ste = get_tle_by_resno(GetCTETargetList(cte), attnum);
/*
* RTE for CTE will already have the search and cycle columns
* added, but the subquery won't, so skip looking those up.
*/
if (cte->search_clause)
extra_cols += 1;
if (cte->cycle_clause)
extra_cols += 2;
if (extra_cols &&
attnum > list_length(tl) &&
attnum <= list_length(tl) + extra_cols)
break;
ste = get_tle_by_resno(tl, attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "CTE %s does not have attribute %d",
rte->eref->aliasname, attnum);