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author | Robert Haas <rhaas@postgresql.org> | 2016-04-08 11:14:56 -0400 |
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committer | Robert Haas <rhaas@postgresql.org> | 2016-04-08 11:14:56 -0400 |
commit | 25fe8b5f1ac93c3ec01519854e4f554b2e57a926 (patch) | |
tree | 38e7e8d5bbe0d6f6ab67f19eb38d0e2e5fdcd9e5 /src | |
parent | b0b64f65054e6b858b845b46298a624aaaea1deb (diff) | |
download | postgresql-25fe8b5f1ac93c3ec01519854e4f554b2e57a926.tar.gz postgresql-25fe8b5f1ac93c3ec01519854e4f554b2e57a926.zip |
Add a 'parallel_degree' reloption.
The code that estimates what parallel degree should be uesd for the
scan of a relation is currently rather stupid, so add a parallel_degree
reloption that can be used to override the planner's rather limited
judgement.
Julien Rouhaud, reviewed by David Rowley, James Sewell, Amit Kapila,
and me. Some further hacking by me.
Diffstat (limited to 'src')
-rw-r--r-- | src/backend/access/common/reloptions.c | 17 | ||||
-rw-r--r-- | src/backend/optimizer/path/allpaths.c | 64 | ||||
-rw-r--r-- | src/backend/optimizer/util/plancat.c | 3 | ||||
-rw-r--r-- | src/backend/optimizer/util/relnode.c | 1 | ||||
-rw-r--r-- | src/bin/psql/tab-complete.c | 1 | ||||
-rw-r--r-- | src/include/nodes/relation.h | 1 | ||||
-rw-r--r-- | src/include/utils/rel.h | 9 |
7 files changed, 73 insertions, 23 deletions
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c index ea0755a8785..797be63c44b 100644 --- a/src/backend/access/common/reloptions.c +++ b/src/backend/access/common/reloptions.c @@ -26,6 +26,7 @@ #include "commands/tablespace.h" #include "commands/view.h" #include "nodes/makefuncs.h" +#include "postmaster/postmaster.h" #include "utils/array.h" #include "utils/attoptcache.h" #include "utils/builtins.h" @@ -267,6 +268,15 @@ static relopt_int intRelOpts[] = 0, 0, 0 #endif }, + { + { + "parallel_degree", + "Number of parallel processes that can be used per executor node for this relation.", + RELOPT_KIND_HEAP, + AccessExclusiveLock + }, + -1, 0, MAX_BACKENDS + }, /* list terminator */ {{NULL}} @@ -1251,8 +1261,7 @@ fillRelOptions(void *rdopts, Size basesize, /* - * Option parser for anything that uses StdRdOptions (i.e. fillfactor and - * autovacuum) + * Option parser for anything that uses StdRdOptions. */ bytea * default_reloptions(Datum reloptions, bool validate, relopt_kind kind) @@ -1291,7 +1300,9 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind) {"autovacuum_analyze_scale_factor", RELOPT_TYPE_REAL, offsetof(StdRdOptions, autovacuum) +offsetof(AutoVacOpts, analyze_scale_factor)}, {"user_catalog_table", RELOPT_TYPE_BOOL, - offsetof(StdRdOptions, user_catalog_table)} + offsetof(StdRdOptions, user_catalog_table)}, + {"parallel_degree", RELOPT_TYPE_INT, + offsetof(StdRdOptions, parallel_degree)} }; options = parseRelOptions(reloptions, validate, kind, &numoptions); diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index cc77ff9e1f0..17c1edd9703 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -659,31 +659,55 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte) static void create_parallel_paths(PlannerInfo *root, RelOptInfo *rel) { - int parallel_threshold = 1000; - int parallel_degree = 1; + int parallel_degree = 1; /* - * If this relation is too small to be worth a parallel scan, just return - * without doing anything ... unless it's an inheritance child. In that case, - * we want to generate a parallel path here anyway. It might not be worthwhile - * just for this relation, but when combined with all of its inheritance siblings - * it may well pay off. + * If the user has set the parallel_degree reloption, we decide what to do + * based on the value of that option. Otherwise, we estimate a value. */ - if (rel->pages < parallel_threshold && rel->reloptkind == RELOPT_BASEREL) - return; + if (rel->rel_parallel_degree != -1) + { + /* + * If parallel_degree = 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) + return; - /* - * Limit the degree of parallelism logarithmically based on the size of the - * relation. This probably needs to be a good deal more sophisticated, but we - * need something here for now. - */ - while (rel->pages > parallel_threshold * 3 && - parallel_degree < max_parallel_degree) + /* + * Use the table parallel_degree, but don't go further than + * max_parallel_degree. + */ + parallel_degree = Min(rel->rel_parallel_degree, max_parallel_degree); + } + else { - parallel_degree++; - parallel_threshold *= 3; - if (parallel_threshold >= PG_INT32_MAX / 3) - break; + int parallel_threshold = 1000; + + /* + * If this relation is too small to be worth a parallel scan, just + * return without doing anything ... unless it's an inheritance child. + * In that case, we want to generate a parallel path here anyway. It + * might not be worthwhile just for this relation, but when combined + * with all of its inheritance siblings it may well pay off. + */ + if (rel->pages < parallel_threshold && + rel->reloptkind == RELOPT_BASEREL) + return; + + /* + * Limit the degree of parallelism logarithmically based on the size + * of the relation. This probably needs to be a good deal more + * sophisticated, but we need something here for now. + */ + while (rel->pages > parallel_threshold * 3 && + parallel_degree < max_parallel_degree) + { + parallel_degree++; + parallel_threshold *= 3; + if (parallel_threshold >= PG_INT32_MAX / 3) + break; + } } /* Add an unordered partial path based on a parallel sequential scan. */ diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index 0f291275dcc..86cc640cf26 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -133,6 +133,9 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent, estimate_rel_size(relation, rel->attr_widths - rel->min_attr, &rel->pages, &rel->tuples, &rel->allvisfrac); + /* Retrive the parallel_degree reloption, if set. */ + rel->rel_parallel_degree = RelationGetParallelDegree(relation, -1); + /* * Make list of indexes. Ignore indexes on system catalogs if told to. * Don't bother with indexes for an inheritance parent, either. diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index 802eab3718a..187437b6941 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -107,6 +107,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind) rel->consider_startup = (root->tuple_fraction > 0); rel->consider_param_startup = false; /* might get changed later */ rel->consider_parallel = false; /* might get changed later */ + rel->rel_parallel_degree = -1; /* set up in GetRelationInfo */ rel->reltarget = create_empty_pathtarget(); rel->pathlist = NIL; rel->ppilist = NIL; diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c index cb8a06d15e4..6d092711e83 100644 --- a/src/bin/psql/tab-complete.c +++ b/src/bin/psql/tab-complete.c @@ -1783,6 +1783,7 @@ psql_completion(const char *text, int start, int end) "autovacuum_vacuum_scale_factor", "autovacuum_vacuum_threshold", "fillfactor", + "parallel_degree", "log_autovacuum_min_duration", "toast.autovacuum_enabled", "toast.autovacuum_freeze_max_age", diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index d430f6e9fd4..e9dfb663c20 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -522,6 +522,7 @@ typedef struct RelOptInfo double allvisfrac; PlannerInfo *subroot; /* if subquery */ List *subplan_params; /* if subquery */ + int rel_parallel_degree; /* wanted number of parallel workers */ /* Information about foreign tables and foreign joins */ Oid serverid; /* identifies server for the table or join */ diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index 51eb27a381b..c7582c2a11c 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -206,6 +206,7 @@ typedef struct StdRdOptions AutoVacOpts autovacuum; /* autovacuum-related options */ bool user_catalog_table; /* use as an additional catalog * relation */ + int parallel_degree; /* max number of parallel workers */ } StdRdOptions; #define HEAP_MIN_FILLFACTOR 10 @@ -242,6 +243,14 @@ typedef struct StdRdOptions ((relation)->rd_options ? \ ((StdRdOptions *) (relation)->rd_options)->user_catalog_table : false) +/* + * RelationGetParallelDegree + * Returns the relation's parallel_degree. Note multiple eval of argument! + */ +#define RelationGetParallelDegree(relation, defaultpd) \ + ((relation)->rd_options ? \ + ((StdRdOptions *) (relation)->rd_options)->parallel_degree : (defaultpd)) + /* * ViewOptions |