database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-15 19:21:59 +03:00
Code Activity

Support parallel bitmap heap scans.

Browse Source 
The index is scanned by a single process, but then all cooperating
processes can iterate jointly over the resulting set of heap blocks.
In the future, we might also want to support using a parallel bitmap
index scan to set up for a parallel bitmap heap scan, but that's a
job for another day.

Dilip Kumar, with some corrections and cosmetic changes by me.  The
larger patch set of which this is a part has been reviewed and tested
by (at least) Andres Freund, Amit Khandekar, Tushar Ahuja, Rafia
Sabih, Haribabu Kommi, Thomas Munro, and me.

Discussion: http://postgr.es/m/CAFiTN-uc4=0WxRGfCzs-xfkMYcSEWUC-Fon6thkJGjkh9i=13A@mail.gmail.com
This commit is contained in:
Robert Haas
2017-03-08 12:05:43 -05:00
parent 4eafdcc276
commit f35742ccb7
24 changed files with 615 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
src/backend/optimizer/path/allpaths.c
View File

@ -2911,6 +2911,30 @@ remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel)
}
}
/*
* create_partial_bitmap_paths
* Build partial bitmap heap path for the relation
*/
void
create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
Path *bitmapqual)
{
int parallel_workers;
double pages_fetched;
/* Compute heap pages for bitmap heap scan */
pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
NULL, NULL);
parallel_workers = compute_parallel_worker(rel, pages_fetched, 0);
if (parallel_workers <= 0)
return;
add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
}
/*
* Compute the number of parallel workers that should be used to scan a
* relation. We compute the parallel workers based on the size of the heap to

16
src/backend/optimizer/path/costsize.c
View File

@ -860,6 +860,7 @@ cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
QualCost qpqual_cost;
Cost cpu_per_tuple;
Cost cost_per_page;
Cost cpu_run_cost;
double tuples_fetched;
double pages_fetched;
double spc_seq_page_cost,
@ -921,8 +922,21 @@ cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
startup_cost += qpqual_cost.startup;
cpu_per_tuple = cpu_tuple_cost + qpqual_cost.per_tuple;
cpu_run_cost = cpu_per_tuple * tuples_fetched;
run_cost += cpu_per_tuple * tuples_fetched;
/* Adjust costing for parallelism, if used. */
if (path->parallel_workers > 0)
{
double parallel_divisor = get_parallel_divisor(path);
/* The CPU cost is divided among all the workers. */
cpu_run_cost /= parallel_divisor;
path->rows = clamp_row_est(path->rows / parallel_divisor);
}
run_cost += cpu_run_cost;
/* tlist eval costs are paid per output row, not per tuple scanned */
startup_cost += path->pathtarget->cost.startup;

19
src/backend/optimizer/path/indxpath.c
View File

@ -337,8 +337,12 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
bpath = create_bitmap_heap_path(root, rel, bitmapqual,
rel->lateral_relids, 1.0);
rel->lateral_relids, 1.0, 0);
add_path(rel, (Path *) bpath);
/* create a partial bitmap heap path */
if (rel->consider_parallel && rel->lateral_relids == NULL)
create_partial_bitmap_paths(root, rel, bitmapqual);
}
/*
@ -410,7 +414,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
required_outer = get_bitmap_tree_required_outer(bitmapqual);
loop_count = get_loop_count(root, rel->relid, required_outer);
bpath = create_bitmap_heap_path(root, rel, bitmapqual,
required_outer, loop_count);
required_outer, loop_count, 0);
add_path(rel, (Path *) bpath);
}
}
@ -1617,6 +1621,11 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
bpath.path.pathkeys = NIL;
bpath.bitmapqual = ipath;
/*
* Check the cost of temporary path without considering parallelism.
* Parallel bitmap heap path will be considered at later stage.
*/
bpath.path.parallel_workers = 0;
cost_bitmap_heap_scan(&bpath.path, root, rel,
bpath.path.param_info,
ipath,
@ -1659,6 +1668,12 @@ bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
bpath.path.pathkeys = NIL;
bpath.bitmapqual = (Path *) &apath;
/*
* Check the cost of temporary path without considering parallelism.
* Parallel bitmap heap path will be considered at later stage.
*/
bpath.path.parallel_workers = 0;
/* Now we can do cost_bitmap_heap_scan */
cost_bitmap_heap_scan(&bpath.path, root, rel,
bpath.path.param_info,