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Cosmetic improvements in setup of planner's per-RTE arrays.

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Merge setup_append_rel_array into setup_simple_rel_arrays.  There's no
particularly good reason to keep them separate, and it's inconsistent
with the lack of separation in expand_planner_arrays.  The only apparent
benefit was that the fast path for trivial queries in query_planner()
doesn't need to set up the append_rel_array; but all we're saving there
is an if-test and NULL assignment, which surely ought to be negligible.

Also improve some obsolete comments.

Discussion: https://postgr.es/m/17220.1565301350@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2019-08-09 12:33:43 -04:00
parent b8f2da0ac5
commit 1661a40505
5 changed files with 34 additions and 47 deletions
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53
src/backend/optimizer/util/relnode.c
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@@ -67,24 +67,30 @@ static void build_child_join_reltarget(PlannerInfo *root,
/*
* setup_simple_rel_arrays
* Prepare the arrays we use for quickly accessing base relations.
* Prepare the arrays we use for quickly accessing base relations
* and AppendRelInfos.
*/
void
setup_simple_rel_arrays(PlannerInfo *root)
{
int size;
Index rti;
ListCell *lc;
/* Arrays are accessed using RT indexes (1..N) */
root->simple_rel_array_size = list_length(root->parse->rtable) + 1;
size = list_length(root->parse->rtable) + 1;
root->simple_rel_array_size = size;
/* simple_rel_array is initialized to all NULLs */
/*
* simple_rel_array is initialized to all NULLs, since no RelOptInfos
* exist yet. It'll be filled by later calls to build_simple_rel().
*/
root->simple_rel_array = (RelOptInfo **)
palloc0(root->simple_rel_array_size * sizeof(RelOptInfo *));
palloc0(size * sizeof(RelOptInfo *));
/* simple_rte_array is an array equivalent of the rtable list */
root->simple_rte_array = (RangeTblEntry **)
palloc0(root->simple_rel_array_size * sizeof(RangeTblEntry *));
palloc0(size * sizeof(RangeTblEntry *));
rti = 1;
foreach(lc, root->parse->rtable)
{
@@ -92,21 +98,8 @@ setup_simple_rel_arrays(PlannerInfo *root)
root->simple_rte_array[rti++] = rte;
}
}
/*
* setup_append_rel_array
* Populate the append_rel_array to allow direct lookups of
* AppendRelInfos by child relid.
*
* The array remains unallocated if there are no AppendRelInfos.
*/
void
setup_append_rel_array(PlannerInfo *root)
{
ListCell *lc;
int size = list_length(root->parse->rtable) + 1;
/* append_rel_array is not needed if there are no AppendRelInfos */
if (root->append_rel_list == NIL)
{
root->append_rel_array = NULL;
@@ -116,6 +109,12 @@ setup_append_rel_array(PlannerInfo *root)
root->append_rel_array = (AppendRelInfo **)
palloc0(size * sizeof(AppendRelInfo *));
/*
* append_rel_array is filled with any already-existing AppendRelInfos,
* which currently could only come from UNION ALL flattening. We might
* add more later during inheritance expansion, but it's the
* responsibility of the expansion code to update the array properly.
*/
foreach(lc, root->append_rel_list)
{
AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, lc);
@@ -135,6 +134,10 @@ setup_append_rel_array(PlannerInfo *root)
* expand_planner_arrays
* Expand the PlannerInfo's per-RTE arrays by add_size members
* and initialize the newly added entries to NULLs
*
* Note: this causes the append_rel_array to become allocated even if
* it was not before. This is okay for current uses, because we only call
* this when adding child relations, which always have AppendRelInfos.
*/
void
expand_planner_arrays(PlannerInfo *root, int add_size)
@@ -145,18 +148,18 @@ expand_planner_arrays(PlannerInfo *root, int add_size)
new_size = root->simple_rel_array_size + add_size;
root->simple_rte_array = (RangeTblEntry **)
repalloc(root->simple_rte_array,
sizeof(RangeTblEntry *) * new_size);
MemSet(root->simple_rte_array + root->simple_rel_array_size,
0, sizeof(RangeTblEntry *) * add_size);
root->simple_rel_array = (RelOptInfo **)
repalloc(root->simple_rel_array,
sizeof(RelOptInfo *) * new_size);
MemSet(root->simple_rel_array + root->simple_rel_array_size,
0, sizeof(RelOptInfo *) * add_size);
root->simple_rte_array = (RangeTblEntry **)
repalloc(root->simple_rte_array,
sizeof(RangeTblEntry *) * new_size);
MemSet(root->simple_rte_array + root->simple_rel_array_size,
0, sizeof(RangeTblEntry *) * add_size);
if (root->append_rel_array)
{
root->append_rel_array = (AppendRelInfo **)