mirror of https://github.com/postgres/postgres
Fix nested PlaceHolderVar expressions that appear only in targetlists.
A PlaceHolderVar's expression might contain another, lower-level PlaceHolderVar. If the outer PlaceHolderVar is used, the inner one certainly will be also, and so we have to make sure that both of them get into the placeholder_list with correct ph_may_need values during the initial pre-scan of the query (before deconstruct_jointree starts). We did this correctly for PlaceHolderVars appearing in the query quals, but overlooked the issue for those appearing in the top-level targetlist; with the result that nested placeholders referenced only in the targetlist did not work correctly, as illustrated in bug #6154. While at it, add some error checking to find_placeholder_info to ensure that we don't try to create new placeholders after it's too late to do so; they have to all be created before deconstruct_jointree starts. Back-patch to 8.4 where the PlaceHolderVar mechanism was introduced.
This commit is contained in:
Tom Lane
parent
d82a9d2a60
commit
77ba232564
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@ -3491,7 +3491,7 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
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else if (IsA(node, PlaceHolderVar))
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{
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PlaceHolderVar *phv = (PlaceHolderVar *) node;
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PlaceHolderInfo *phinfo = find_placeholder_info(root, phv);
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PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, false);
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tuple_width += phinfo->ph_width;
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}
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@ -850,7 +850,7 @@ generate_base_implied_equalities_no_const(PlannerInfo *root,
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PVC_RECURSE_AGGREGATES,
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PVC_INCLUDE_PLACEHOLDERS);
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add_vars_to_targetlist(root, vars, ec->ec_relids);
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add_vars_to_targetlist(root, vars, ec->ec_relids, false);
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list_free(vars);
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}
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}
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@ -137,7 +137,7 @@ build_base_rel_tlists(PlannerInfo *root, List *final_tlist)
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if (tlist_vars != NIL)
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{
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add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0));
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add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0), true);
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list_free(tlist_vars);
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}
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}
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@ -151,10 +151,15 @@ build_base_rel_tlists(PlannerInfo *root, List *final_tlist)
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*
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* The list may also contain PlaceHolderVars. These don't necessarily
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* have a single owning relation; we keep their attr_needed info in
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* root->placeholder_list instead.
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* root->placeholder_list instead. If create_new_ph is true, it's OK
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* to create new PlaceHolderInfos, and we also have to update ph_may_need;
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* otherwise, the PlaceHolderInfos must already exist, and we should only
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* update their ph_needed. (It should be true before deconstruct_jointree
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* begins, and false after that.)
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*/
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void
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add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed)
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add_vars_to_targetlist(PlannerInfo *root, List *vars,
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Relids where_needed, bool create_new_ph)
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{
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ListCell *temp;
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@ -185,18 +190,20 @@ add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed)
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else if (IsA(node, PlaceHolderVar))
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{
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PlaceHolderVar *phv = (PlaceHolderVar *) node;
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PlaceHolderInfo *phinfo = find_placeholder_info(root, phv);
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PlaceHolderInfo *phinfo = find_placeholder_info(root, phv,
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create_new_ph);
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/* Always adjust ph_needed */
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phinfo->ph_needed = bms_add_members(phinfo->ph_needed,
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where_needed);
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/*
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* Update ph_may_need too. This is currently only necessary when
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* being called from build_base_rel_tlists, but we may as well do
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* it always.
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* If we are creating PlaceHolderInfos, mark them with the
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* correct maybe-needed locations. Otherwise, it's too late to
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* change that.
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*/
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phinfo->ph_may_need = bms_add_members(phinfo->ph_may_need,
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where_needed);
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if (create_new_ph)
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mark_placeholder_maybe_needed(root, phinfo, where_needed);
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}
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else
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elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
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@ -1035,7 +1042,7 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
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PVC_RECURSE_AGGREGATES,
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PVC_INCLUDE_PLACEHOLDERS);
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add_vars_to_targetlist(root, vars, relids);
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add_vars_to_targetlist(root, vars, relids, false);
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list_free(vars);
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}
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@ -24,7 +24,7 @@
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/* Local functions */
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static Relids find_placeholders_recurse(PlannerInfo *root, Node *jtnode);
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static void find_placeholders_in_qual(PlannerInfo *root, Node *qual,
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static void mark_placeholders_in_expr(PlannerInfo *root, Node *expr,
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Relids relids);
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@ -50,7 +50,10 @@ make_placeholder_expr(PlannerInfo *root, Expr *expr, Relids phrels)
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/*
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* find_placeholder_info
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* Fetch the PlaceHolderInfo for the given PHV; create it if not found
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* Fetch the PlaceHolderInfo for the given PHV
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*
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* If the PlaceHolderInfo doesn't exist yet, create it if create_new_ph is
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* true, else throw an error.
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*
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* This is separate from make_placeholder_expr because subquery pullup has
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* to make PlaceHolderVars for expressions that might not be used at all in
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@ -58,10 +61,13 @@ make_placeholder_expr(PlannerInfo *root, Expr *expr, Relids phrels)
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* We build PlaceHolderInfos only for PHVs that are still present in the
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* simplified query passed to query_planner().
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*
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* Note: this should only be called after query_planner() has started.
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* Note: this should only be called after query_planner() has started. Also,
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* create_new_ph must not be TRUE after deconstruct_jointree begins, because
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* make_outerjoininfo assumes that we already know about all placeholders.
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*/
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PlaceHolderInfo *
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find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv)
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find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv,
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bool create_new_ph)
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{
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PlaceHolderInfo *phinfo;
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ListCell *lc;
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@ -77,6 +83,9 @@ find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv)
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}
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/* Not found, so create it */
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if (!create_new_ph)
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elog(ERROR, "too late to create a new PlaceHolderInfo");
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phinfo = makeNode(PlaceHolderInfo);
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phinfo->phid = phv->phid;
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@ -157,7 +166,7 @@ find_placeholders_recurse(PlannerInfo *root, Node *jtnode)
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/*
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* Now process the top-level quals.
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*/
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find_placeholders_in_qual(root, f->quals, jtrelids);
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mark_placeholders_in_expr(root, f->quals, jtrelids);
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}
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else if (IsA(jtnode, JoinExpr))
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{
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@ -173,7 +182,7 @@ find_placeholders_recurse(PlannerInfo *root, Node *jtnode)
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jtrelids = bms_join(leftids, rightids);
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/* Process the qual clauses */
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find_placeholders_in_qual(root, j->quals, jtrelids);
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mark_placeholders_in_expr(root, j->quals, jtrelids);
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}
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else
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{
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@ -185,14 +194,15 @@ find_placeholders_recurse(PlannerInfo *root, Node *jtnode)
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}
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/*
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* find_placeholders_in_qual
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* Process a qual clause for find_placeholders_in_jointree.
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* mark_placeholders_in_expr
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* Find all PlaceHolderVars in the given expression, and mark them
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* as possibly needed at the specified join level.
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*
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* relids is the syntactic join level to mark as the "maybe needed" level
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* for each PlaceHolderVar found in the qual clause.
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* for each PlaceHolderVar found in the expression.
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*/
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static void
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find_placeholders_in_qual(PlannerInfo *root, Node *qual, Relids relids)
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mark_placeholders_in_expr(PlannerInfo *root, Node *expr, Relids relids)
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{
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List *vars;
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ListCell *vl;
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@ -201,7 +211,7 @@ find_placeholders_in_qual(PlannerInfo *root, Node *qual, Relids relids)
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* pull_var_clause does more than we need here, but it'll do and it's
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* convenient to use.
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*/
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vars = pull_var_clause(qual,
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vars = pull_var_clause(expr,
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PVC_RECURSE_AGGREGATES,
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PVC_INCLUDE_PLACEHOLDERS);
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foreach(vl, vars)
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@ -214,23 +224,45 @@ find_placeholders_in_qual(PlannerInfo *root, Node *qual, Relids relids)
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continue;
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/* Create a PlaceHolderInfo entry if there's not one already */
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phinfo = find_placeholder_info(root, phv);
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phinfo = find_placeholder_info(root, phv, true);
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/* Mark the PHV as possibly needed at the qual's syntactic level */
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/* Mark it, and recursively process any contained placeholders */
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mark_placeholder_maybe_needed(root, phinfo, relids);
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}
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list_free(vars);
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}
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/*
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* mark_placeholder_maybe_needed
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* Mark a placeholder as possibly needed at the specified join level.
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*
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* relids is the syntactic join level to mark as the "maybe needed" level
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* for the placeholder.
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*
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* This is called during an initial scan of the query's targetlist and quals
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* before we begin deconstruct_jointree. Once we begin deconstruct_jointree,
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* all active placeholders must be present in root->placeholder_list with
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* their correct ph_may_need values, because make_outerjoininfo and
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* update_placeholder_eval_levels require this info to be available while
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* we crawl up the join tree.
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*/
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void
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mark_placeholder_maybe_needed(PlannerInfo *root, PlaceHolderInfo *phinfo,
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Relids relids)
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{
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/* Mark the PHV as possibly needed at the given syntactic level */
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phinfo->ph_may_need = bms_add_members(phinfo->ph_may_need, relids);
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/*
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* This is a bit tricky: the PHV's contained expression may contain
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* other, lower-level PHVs. We need to get those into the
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* PlaceHolderInfo list, but they aren't going to be needed where the
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* outer PHV is referenced. Rather, they'll be needed where the outer
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* PHV is evaluated. We can estimate that (conservatively) as the
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* syntactic location of the PHV's expression. Recurse to take care
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* of any such PHVs.
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* This is a bit tricky: the PHV's contained expression may contain other,
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* lower-level PHVs. We need to get those into the PlaceHolderInfo list,
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* but they aren't going to be needed where the outer PHV is referenced.
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* Rather, they'll be needed where the outer PHV is evaluated. We can
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* estimate that (conservatively) as the syntactic location of the PHV's
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* expression. Recurse to take care of any such PHVs.
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*/
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find_placeholders_in_qual(root, (Node *) phv->phexpr, phv->phrels);
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}
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list_free(vars);
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mark_placeholders_in_expr(root, (Node *) phinfo->ph_var->phexpr,
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phinfo->ph_var->phrels);
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}
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/*
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@ -353,7 +385,7 @@ fix_placeholder_input_needed_levels(PlannerInfo *root)
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PVC_RECURSE_AGGREGATES,
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PVC_INCLUDE_PLACEHOLDERS);
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add_vars_to_targetlist(root, vars, eval_at);
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add_vars_to_targetlist(root, vars, eval_at, false);
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list_free(vars);
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}
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}
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@ -20,8 +20,10 @@
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extern PlaceHolderVar *make_placeholder_expr(PlannerInfo *root, Expr *expr,
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Relids phrels);
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extern PlaceHolderInfo *find_placeholder_info(PlannerInfo *root,
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PlaceHolderVar *phv);
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PlaceHolderVar *phv, bool create_new_ph);
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extern void find_placeholders_in_jointree(PlannerInfo *root);
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extern void mark_placeholder_maybe_needed(PlannerInfo *root,
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PlaceHolderInfo *phinfo, Relids relids);
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extern void update_placeholder_eval_levels(PlannerInfo *root,
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SpecialJoinInfo *new_sjinfo);
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extern void fix_placeholder_input_needed_levels(PlannerInfo *root);
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@ -92,7 +92,7 @@ extern int join_collapse_limit;
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extern void add_base_rels_to_query(PlannerInfo *root, Node *jtnode);
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extern void build_base_rel_tlists(PlannerInfo *root, List *final_tlist);
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extern void add_vars_to_targetlist(PlannerInfo *root, List *vars,
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Relids where_needed);
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Relids where_needed, bool create_new_ph);
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extern List *deconstruct_jointree(PlannerInfo *root);
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extern void distribute_restrictinfo_to_rels(PlannerInfo *root,
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RestrictInfo *restrictinfo);
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@ -2488,6 +2488,51 @@ order by c.name;
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(3 rows)
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rollback;
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--
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-- test incorrect handling of placeholders that only appear in targetlists,
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-- per bug #6154
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--
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SELECT * FROM
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( SELECT 1 as key1 ) sub1
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LEFT JOIN
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( SELECT sub3.key3, sub4.value2, COALESCE(sub4.value2, 66) as value3 FROM
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( SELECT 1 as key3 ) sub3
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LEFT JOIN
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( SELECT sub5.key5, COALESCE(sub6.value1, 1) as value2 FROM
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( SELECT 1 as key5 ) sub5
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LEFT JOIN
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( SELECT 2 as key6, 42 as value1 ) sub6
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ON sub5.key5 = sub6.key6
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) sub4
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ON sub4.key5 = sub3.key3
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) sub2
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ON sub1.key1 = sub2.key3;
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key1 | key3 | value2 | value3
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------+------+--------+--------
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1 | 1 | 1 | 1
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(1 row)
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-- test the path using join aliases, too
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SELECT * FROM
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( SELECT 1 as key1 ) sub1
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LEFT JOIN
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( SELECT sub3.key3, value2, COALESCE(value2, 66) as value3 FROM
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( SELECT 1 as key3 ) sub3
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LEFT JOIN
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( SELECT sub5.key5, COALESCE(sub6.value1, 1) as value2 FROM
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( SELECT 1 as key5 ) sub5
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LEFT JOIN
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( SELECT 2 as key6, 42 as value1 ) sub6
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ON sub5.key5 = sub6.key6
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) sub4
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ON sub4.key5 = sub3.key3
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) sub2
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ON sub1.key1 = sub2.key3;
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key1 | key3 | value2 | value3
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------+------+--------+--------
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1 | 1 | 1 | 1
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(1 row)
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--
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-- test the corner cases FULL JOIN ON TRUE and FULL JOIN ON FALSE
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--
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@ -602,6 +602,43 @@ order by c.name;
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rollback;
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--
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-- test incorrect handling of placeholders that only appear in targetlists,
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-- per bug #6154
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--
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SELECT * FROM
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( SELECT 1 as key1 ) sub1
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LEFT JOIN
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( SELECT sub3.key3, sub4.value2, COALESCE(sub4.value2, 66) as value3 FROM
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( SELECT 1 as key3 ) sub3
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LEFT JOIN
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( SELECT sub5.key5, COALESCE(sub6.value1, 1) as value2 FROM
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( SELECT 1 as key5 ) sub5
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LEFT JOIN
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( SELECT 2 as key6, 42 as value1 ) sub6
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ON sub5.key5 = sub6.key6
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) sub4
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ON sub4.key5 = sub3.key3
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) sub2
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ON sub1.key1 = sub2.key3;
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-- test the path using join aliases, too
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SELECT * FROM
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( SELECT 1 as key1 ) sub1
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LEFT JOIN
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( SELECT sub3.key3, value2, COALESCE(value2, 66) as value3 FROM
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( SELECT 1 as key3 ) sub3
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LEFT JOIN
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( SELECT sub5.key5, COALESCE(sub6.value1, 1) as value2 FROM
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( SELECT 1 as key5 ) sub5
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LEFT JOIN
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( SELECT 2 as key6, 42 as value1 ) sub6
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ON sub5.key5 = sub6.key6
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) sub4
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ON sub4.key5 = sub3.key3
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) sub2
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ON sub1.key1 = sub2.key3;
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--
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-- test the corner cases FULL JOIN ON TRUE and FULL JOIN ON FALSE
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--
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