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Eliminate "parallel degree" terminology.

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This terminology provoked widespread complaints.  So, instead, rename
the GUC max_parallel_degree to max_parallel_workers_per_gather
(leaving room for a possible future GUC max_parallel_workers that acts
as a system-wide limit), and rename the parallel_degree reloption to
parallel_workers.  Rename structure members to match.

These changes create a dump/restore hazard for users of PostgreSQL
9.6beta1 who have set the reloption (or applied the GUC using ALTER
USER or ALTER DATABASE).
This commit is contained in:
Robert Haas
2016-06-09 09:08:27 -04:00
parent 6581e930a8
commit c9ce4a1c61
19 changed files with 99 additions and 99 deletions
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34
src/backend/optimizer/path/allpaths.c
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@ -669,26 +669,26 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
static void
create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
{
int parallel_degree = 1;
int parallel_workers = 1;
/*
* If the user has set the parallel_degree reloption, we decide what to do
* If the user has set the parallel_workers reloption, we decide what to do
* based on the value of that option. Otherwise, we estimate a value.
*/
if (rel->rel_parallel_degree != -1)
if (rel->rel_parallel_workers != -1)
{
/*
* If parallel_degree = 0 is set for this relation, bail out. The
* If parallel_workers = 0 is set for this relation, bail out. The
* user does not want a parallel path for this relation.
*/
if (rel->rel_parallel_degree == 0)
if (rel->rel_parallel_workers == 0)
return;
/*
* Use the table parallel_degree, but don't go further than
* max_parallel_degree.
* Use the table parallel_workers, but don't go further than
* max_parallel_workers_per_gather.
*/
parallel_degree = Min(rel->rel_parallel_degree, max_parallel_degree);
parallel_workers = Min(rel->rel_parallel_workers, max_parallel_workers_per_gather);
}
else
{
@ -711,9 +711,9 @@ create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
* sophisticated, but we need something here for now.
*/
while (rel->pages > parallel_threshold * 3 &&
parallel_degree < max_parallel_degree)
parallel_workers < max_parallel_workers_per_gather)
{
parallel_degree++;
parallel_workers++;
parallel_threshold *= 3;
if (parallel_threshold >= PG_INT32_MAX / 3)
break;
@ -721,7 +721,7 @@ create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
}
/* Add an unordered partial path based on a parallel sequential scan. */
add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_degree));
add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
}
/*
@ -1242,11 +1242,11 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
{
AppendPath *appendpath;
ListCell *lc;
int parallel_degree = 0;
int parallel_workers = 0;
/*
* Decide what parallel degree to request for this append path. For
* now, we just use the maximum parallel degree of any member. It
* Decide on the numebr of workers to request for this append path. For
* now, we just use the maximum value from among the members. It
* might be useful to use a higher number if the Append node were
* smart enough to spread out the workers, but it currently isn't.
*/
@ -1254,13 +1254,13 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
{
Path *path = lfirst(lc);
parallel_degree = Max(parallel_degree, path->parallel_degree);
parallel_workers = Max(parallel_workers, path->parallel_workers);
}
Assert(parallel_degree > 0);
Assert(parallel_workers > 0);
/* Generate a partial append path. */
appendpath = create_append_path(rel, partial_subpaths, NULL,
parallel_degree);
parallel_workers);
add_partial_path(rel, (Path *) appendpath);
}