diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepjointree.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepjointree.c | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c index aeaae8c8d87..8bb011b7116 100644 --- a/src/backend/optimizer/prep/prepjointree.c +++ b/src/backend/optimizer/prep/prepjointree.c @@ -784,22 +784,15 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext); /* - * Replace references in the translated_vars lists of appendrels. When - * pulling up an appendrel member, we do not need PHVs in the list of the - * parent appendrel --- there isn't any outer join between. Elsewhere, use - * PHVs for safety. (This analysis could be made tighter but it seems - * unlikely to be worth much trouble.) + * Replace references in the translated_vars lists of appendrels, too. + * We do it this way because we must preserve the AppendRelInfo structs. */ foreach(lc, root->append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc); - bool save_need_phvs = rvcontext.need_phvs; - if (appinfo == containing_appendrel) - rvcontext.need_phvs = false; appinfo->translated_vars = (List *) pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext); - rvcontext.need_phvs = save_need_phvs; } /* @@ -1407,14 +1400,31 @@ pullup_replace_vars_callback(Var *var, if (newnode && IsA(newnode, Var) && ((Var *) newnode)->varlevelsup == 0) { - /* Simple Vars always escape being wrapped */ - wrap = false; + /* + * Simple Vars normally escape being wrapped. However, in + * wrap_non_vars mode (ie, we are dealing with an appendrel + * member), we must ensure that each tlist entry expands to a + * distinct expression, else we may have problems with + * improperly placing identical entries into different + * EquivalenceClasses. Therefore, we wrap a Var in a + * PlaceHolderVar if it duplicates any earlier entry in the + * tlist (ie, we've got "SELECT x, x, ..."). Since each PHV + * is distinct, this fixes the ambiguity. We can use + * tlist_member to detect whether there's an earlier + * duplicate. + */ + wrap = (rcon->wrap_non_vars && + tlist_member(newnode, rcon->targetlist) != tle); } else if (newnode && IsA(newnode, PlaceHolderVar) && ((PlaceHolderVar *) newnode)->phlevelsup == 0) { - /* No need to wrap a PlaceHolderVar with another one, either */ - wrap = false; + /* + * No need to directly wrap a PlaceHolderVar with another one, + * either, unless we need to prevent duplication. + */ + wrap = (rcon->wrap_non_vars && + tlist_member(newnode, rcon->targetlist) != tle); } else if (rcon->wrap_non_vars) { |