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Support flattening of empty-FROM subqueries and one-row VALUES tables.

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We can't handle this in the general case due to limitations of the
planner's data representations; but we can allow it in many useful cases,
by being careful to flatten only when we are pulling a single-row subquery
up into a FROM (or, equivalently, inner JOIN) node that will still have at
least one remaining relation child.  Per discussion of an example from
Kyotaro Horiguchi.
This commit is contained in:
Tom Lane
2015-03-11 23:18:03 -04:00
parent b746d0c32d
commit f4abd0241d
9 changed files with 466 additions and 71 deletions
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2
src/include/optimizer/prep.h
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@@ -23,7 +23,7 @@
*/
extern void pull_up_sublinks(PlannerInfo *root);
extern void inline_set_returning_functions(PlannerInfo *root);
extern Node *pull_up_subqueries(PlannerInfo *root, Node *jtnode);
extern void pull_up_subqueries(PlannerInfo *root);
extern void flatten_simple_union_all(PlannerInfo *root);
extern void reduce_outer_joins(PlannerInfo *root);
extern Relids get_relids_in_jointree(Node *jtnode, bool include_joins);