* Planner preprocessing for subqueries and join tree manipulation.
*
* NOTE: the intended sequence for invoking these operations is
- * expand_virtual_generated_columns
+ * preprocess_relation_rtes
* replace_empty_jointree
* pull_up_sublinks
* preprocess_function_rtes
Relids unreduced_side; /* relids in its still-nullable side */
} reduce_outer_joins_partial_state;
+static Query *expand_virtual_generated_columns(PlannerInfo *root, Query *parse,
+ RangeTblEntry *rte, int rt_index,
+ Relation relation);
static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
Relids *relids);
static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
parse->mergeJoinCondition = NULL; /* join condition not needed */
}
+/*
+ * preprocess_relation_rtes
+ * Do the preprocessing work for any relation RTEs in the FROM clause.
+ *
+ * This scans the rangetable for relation RTEs and retrieves the necessary
+ * catalog information for each relation. Using this information, it clears
+ * the inh flag for any relation that has no children, and expands virtual
+ * generated columns for any relation that contains them.
+ *
+ * Note that expanding virtual generated columns may cause the query tree to
+ * have new copies of rangetable entries. Therefore, we have to use list_nth
+ * instead of foreach when iterating over the query's rangetable.
+ *
+ * Returns a modified copy of the query tree, if any relations with virtual
+ * generated columns are present.
+ */
+Query *
+preprocess_relation_rtes(PlannerInfo *root)
+{
+ Query *parse = root->parse;
+ int rtable_size;
+ int rt_index;
+
+ rtable_size = list_length(parse->rtable);
+
+ for (rt_index = 0; rt_index < rtable_size; rt_index++)
+ {
+ RangeTblEntry *rte = rt_fetch(rt_index + 1, parse->rtable);
+ Relation relation;
+
+ /* We only care about relation RTEs. */
+ if (rte->rtekind != RTE_RELATION)
+ continue;
+
+ /*
+ * We need not lock the relation since it was already locked by the
+ * rewriter.
+ */
+ relation = table_open(rte->relid, NoLock);
+
+ /*
+ * Check to see if the relation actually has any children; if not,
+ * clear the inh flag so we can treat it as a plain base relation.
+ *
+ * Note: this could give a false-positive result, if the rel once had
+ * children but no longer does. We used to be able to clear rte->inh
+ * later on when we discovered that, but no more; we have to handle
+ * such cases as full-fledged inheritance.
+ */
+ if (rte->inh)
+ rte->inh = relation->rd_rel->relhassubclass;
+
+ /*
+ * Check to see if the relation has any virtual generated columns; if
+ * so, replace all Var nodes in the query that reference these columns
+ * with the generation expressions.
+ */
+ parse = expand_virtual_generated_columns(root, parse,
+ rte, rt_index + 1,
+ relation);
+
+ table_close(relation, NoLock);
+ }
+
+ return parse;
+}
+
+/*
+ * expand_virtual_generated_columns
+ * Expand virtual generated columns for the given relation.
+ *
+ * This checks whether the given relation has any virtual generated columns,
+ * and if so, replaces all Var nodes in the query that reference those columns
+ * with their generation expressions.
+ *
+ * Returns a modified copy of the query tree if the relation contains virtual
+ * generated columns.
+ */
+static Query *
+expand_virtual_generated_columns(PlannerInfo *root, Query *parse,
+ RangeTblEntry *rte, int rt_index,
+ Relation relation)
+{
+ TupleDesc tupdesc;
+
+ /* Only normal relations can have virtual generated columns */
+ Assert(rte->rtekind == RTE_RELATION);
+
+ tupdesc = RelationGetDescr(relation);
+ if (tupdesc->constr && tupdesc->constr->has_generated_virtual)
+ {
+ List *tlist = NIL;
+ pullup_replace_vars_context rvcontext;
+
+ for (int i = 0; i < tupdesc->natts; i++)
+ {
+ Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
+ TargetEntry *tle;
+
+ if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+ {
+ Node *defexpr;
+
+ defexpr = build_generation_expression(relation, i + 1);
+ ChangeVarNodes(defexpr, 1, rt_index, 0);
+
+ tle = makeTargetEntry((Expr *) defexpr, i + 1, 0, false);
+ tlist = lappend(tlist, tle);
+ }
+ else
+ {
+ Var *var;
+
+ var = makeVar(rt_index,
+ i + 1,
+ attr->atttypid,
+ attr->atttypmod,
+ attr->attcollation,
+ 0);
+
+ tle = makeTargetEntry((Expr *) var, i + 1, 0, false);
+ tlist = lappend(tlist, tle);
+ }
+ }
+
+ Assert(list_length(tlist) > 0);
+ Assert(!rte->lateral);
+
+ /*
+ * The relation's targetlist items are now in the appropriate form to
+ * insert into the query, except that we may need to wrap them in
+ * PlaceHolderVars. Set up required context data for
+ * pullup_replace_vars.
+ */
+ rvcontext.root = root;
+ rvcontext.targetlist = tlist;
+ rvcontext.target_rte = rte;
+ rvcontext.result_relation = parse->resultRelation;
+ /* won't need these values */
+ rvcontext.relids = NULL;
+ rvcontext.nullinfo = NULL;
+ /* pass NULL for outer_hasSubLinks */
+ rvcontext.outer_hasSubLinks = NULL;
+ rvcontext.varno = rt_index;
+ /* this flag will be set below, if needed */
+ rvcontext.wrap_option = REPLACE_WRAP_NONE;
+ /* initialize cache array with indexes 0 .. length(tlist) */
+ rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
+ sizeof(Node *));
+
+ /*
+ * If the query uses grouping sets, we need a PlaceHolderVar for each
+ * expression of the relation's targetlist items. (See comments in
+ * pull_up_simple_subquery().)
+ */
+ if (parse->groupingSets)
+ rvcontext.wrap_option = REPLACE_WRAP_ALL;
+
+ /*
+ * Apply pullup variable replacement throughout the query tree.
+ */
+ parse = (Query *) pullup_replace_vars((Node *) parse, &rvcontext);
+ }
+
+ return parse;
+}
+
/*
* replace_empty_jointree
* If the Query's jointree is empty, replace it with a dummy RTE_RESULT
}
}
-/*
- * expand_virtual_generated_columns
- * Expand all virtual generated column references in a query.
- *
- * This scans the rangetable for relations with virtual generated columns, and
- * replaces all Var nodes in the query that reference these columns with the
- * generation expressions. Note that we do not descend into subqueries; that
- * is taken care of when the subqueries are planned.
- *
- * Returns a modified copy of the query tree, if any relations with virtual
- * generated columns are present.
- */
-Query *
-expand_virtual_generated_columns(PlannerInfo *root)
-{
- Query *parse = root->parse;
- int rt_index;
- ListCell *lc;
-
- rt_index = 0;
- foreach(lc, parse->rtable)
- {
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
- Relation rel;
- TupleDesc tupdesc;
-
- ++rt_index;
-
- /*
- * Only normal relations can have virtual generated columns.
- */
- if (rte->rtekind != RTE_RELATION)
- continue;
-
- rel = table_open(rte->relid, NoLock);
-
- tupdesc = RelationGetDescr(rel);
- if (tupdesc->constr && tupdesc->constr->has_generated_virtual)
- {
- List *tlist = NIL;
- pullup_replace_vars_context rvcontext;
-
- for (int i = 0; i < tupdesc->natts; i++)
- {
- Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
- TargetEntry *tle;
-
- if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
- {
- Node *defexpr;
-
- defexpr = build_generation_expression(rel, i + 1);
- ChangeVarNodes(defexpr, 1, rt_index, 0);
-
- tle = makeTargetEntry((Expr *) defexpr, i + 1, 0, false);
- tlist = lappend(tlist, tle);
- }
- else
- {
- Var *var;
-
- var = makeVar(rt_index,
- i + 1,
- attr->atttypid,
- attr->atttypmod,
- attr->attcollation,
- 0);
-
- tle = makeTargetEntry((Expr *) var, i + 1, 0, false);
- tlist = lappend(tlist, tle);
- }
- }
-
- Assert(list_length(tlist) > 0);
- Assert(!rte->lateral);
-
- /*
- * The relation's targetlist items are now in the appropriate form
- * to insert into the query, except that we may need to wrap them
- * in PlaceHolderVars. Set up required context data for
- * pullup_replace_vars.
- */
- rvcontext.root = root;
- rvcontext.targetlist = tlist;
- rvcontext.target_rte = rte;
- rvcontext.result_relation = parse->resultRelation;
- /* won't need these values */
- rvcontext.relids = NULL;
- rvcontext.nullinfo = NULL;
- /* pass NULL for outer_hasSubLinks */
- rvcontext.outer_hasSubLinks = NULL;
- rvcontext.varno = rt_index;
- /* this flag will be set below, if needed */
- rvcontext.wrap_option = REPLACE_WRAP_NONE;
- /* initialize cache array with indexes 0 .. length(tlist) */
- rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
- sizeof(Node *));
-
- /*
- * If the query uses grouping sets, we need a PlaceHolderVar for
- * each expression of the relation's targetlist items. (See
- * comments in pull_up_simple_subquery().)
- */
- if (parse->groupingSets)
- rvcontext.wrap_option = REPLACE_WRAP_ALL;
-
- /*
- * Apply pullup variable replacement throughout the query tree.
- */
- parse = (Query *) pullup_replace_vars((Node *) parse, &rvcontext);
- }
-
- table_close(rel, NoLock);
- }
-
- return parse;
-}
-
/*
* pull_up_subqueries
* Look for subqueries in the rangetable that can be pulled up into
Assert(subquery->cteList == NIL);
/*
- * Scan the rangetable for relations with virtual generated columns, and
- * replace all Var nodes in the subquery that reference these columns with
- * the generation expressions.
+ * Scan the rangetable for relation RTEs and retrieve the necessary
+ * catalog information for each relation. Using this information, clear
+ * the inh flag for any relation that has no children, and expand virtual
+ * generated columns for any relation that contains them.
*/
- subquery = subroot->parse = expand_virtual_generated_columns(subroot);
+ subquery = subroot->parse = preprocess_relation_rtes(subroot);
/*
* If the FROM clause is empty, replace it with a dummy RTE_RESULT RTE, so
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