diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepunion.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepunion.c | 58 |
1 files changed, 32 insertions, 26 deletions
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 12d492f8038..ba1de1b8860 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.116 2004/08/29 05:06:44 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.117 2004/10/02 22:39:47 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -705,24 +705,23 @@ find_all_inheritors(Oid parentrel) * whole inheritance set (parent and children). * If not, return NIL. * - * When dup_parent is false, the initially given RT index is part of the - * returned list (if any). When dup_parent is true, the given RT index - * is *not* in the returned list; a duplicate RTE will be made for the - * parent table. + * Note that the original RTE is considered to represent the whole + * inheritance set. The first member of the returned list is an RTE + * for the same table, but with inh = false, to represent the parent table + * in its role as a simple member of the set. The original RT index is + * never a member of the returned list. * * A childless table is never considered to be an inheritance set; therefore * the result will never be a one-element list. It'll be either empty * or have two or more elements. * - * NOTE: after this routine executes, the specified RTE will always have - * its inh flag cleared, whether or not there were any children. This - * ensures we won't expand the same RTE twice, which would otherwise occur - * for the case of an inherited UPDATE/DELETE target relation. - * - * XXX probably should convert the result type to Relids? + * Note: there are cases in which this routine will be invoked multiple + * times on the same RTE. We will generate a separate set of child RTEs + * for each invocation. This is somewhat wasteful but seems not worth + * trying to avoid. */ List * -expand_inherited_rtentry(Query *parse, Index rti, bool dup_parent) +expand_inherited_rtentry(Query *parse, Index rti) { RangeTblEntry *rte = rt_fetch(rti, parse->rtable); Oid parentOID; @@ -734,12 +733,14 @@ expand_inherited_rtentry(Query *parse, Index rti, bool dup_parent) if (!rte->inh) return NIL; Assert(rte->rtekind == RTE_RELATION); - /* Always clear the parent's inh flag, see above comments */ - rte->inh = false; /* Fast path for common case of childless table */ parentOID = rte->relid; if (!has_subclass(parentOID)) + { + /* Clear flag to save repeated tests if called again */ + rte->inh = false; return NIL; + } /* Scan for all members of inheritance set */ inhOIDs = find_all_inheritors(parentOID); @@ -749,37 +750,42 @@ expand_inherited_rtentry(Query *parse, Index rti, bool dup_parent) * table once had a child but no longer does. */ if (list_length(inhOIDs) < 2) + { + /* Clear flag to save repeated tests if called again */ + rte->inh = false; return NIL; - /* OK, it's an inheritance set; expand it */ - if (dup_parent) - inhRTIs = NIL; - else - inhRTIs = list_make1_int(rti); /* include original RTE in result */ + } + /* OK, it's an inheritance set; expand it */ + inhRTIs = NIL; foreach(l, inhOIDs) { Oid childOID = lfirst_oid(l); RangeTblEntry *childrte; Index childRTindex; - /* parent will be in the list too; skip it if not dup requested */ - if (childOID == parentOID && !dup_parent) - continue; - /* * Build an RTE for the child, and attach to query's rangetable * list. We copy most fields of the parent's RTE, but replace - * relation real name and OID. Note that inh will be false at - * this point. + * relation OID, and set inh = false. */ childrte = copyObject(rte); childrte->relid = childOID; + childrte->inh = false; parse->rtable = lappend(parse->rtable, childrte); childRTindex = list_length(parse->rtable); - inhRTIs = lappend_int(inhRTIs, childRTindex); } + /* + * The executor will check the parent table's access permissions when + * it examines the parent's inheritlist entry. There's no need to + * check twice, so turn off access check bits in the original RTE. + * (If we are invoked more than once, extra copies of the child RTEs + * will also not cause duplicate permission checks.) + */ + rte->requiredPerms = 0; + return inhRTIs; } |