diff options
| author | Robert Haas | 2015-09-30 23:23:36 +0000 |
|---|---|---|
| committer | Robert Haas | 2015-09-30 23:23:36 +0000 |
| commit | 3bd909b220930f21d6e15833a17947be749e7fde (patch) | |
| tree | 1d172ebc5f58b4b864539dc672ece0894df445c0 /src/include/optimizer | |
| parent | 227d57f3587d7d2a7d0792011f5ac952ba763681 (diff) | |
Add a Gather executor node.
A Gather executor node runs any number of copies of a plan in an equal
number of workers and merges all of the results into a single tuple
stream. It can also run the plan itself, if the workers are
unavailable or haven't started up yet. It is intended to work with
the Partial Seq Scan node which will be added in future commits.
It could also be used to implement parallel query of a different sort
by itself, without help from Partial Seq Scan, if the single_copy mode
is used. In that mode, a worker executes the plan, and the parallel
leader does not, merely collecting the worker's results. So, a Gather
node could be inserted into a plan to split the execution of that plan
across two processes. Nested Gather nodes aren't currently supported,
but we might want to add support for that in the future.
There's nothing in the planner to actually generate Gather nodes yet,
so it's not quite time to break out the champagne. But we're getting
close.
Amit Kapila. Some designs suggestions were provided by me, and I also
reviewed the patch. Single-copy mode, documentation, and other minor
changes also by me.
Diffstat (limited to 'src/include/optimizer')
| -rw-r--r-- | src/include/optimizer/cost.h | 7 | ||||
| -rw-r--r-- | src/include/optimizer/pathnode.h | 3 |
2 files changed, 10 insertions, 0 deletions
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h index dd43e45d0c0..25a730362a8 100644 --- a/src/include/optimizer/cost.h +++ b/src/include/optimizer/cost.h @@ -26,6 +26,8 @@ #define DEFAULT_CPU_TUPLE_COST 0.01 #define DEFAULT_CPU_INDEX_TUPLE_COST 0.005 #define DEFAULT_CPU_OPERATOR_COST 0.0025 +#define DEFAULT_PARALLEL_TUPLE_COST 0.1 +#define DEFAULT_PARALLEL_SETUP_COST 1000.0 #define DEFAULT_EFFECTIVE_CACHE_SIZE 524288 /* measured in pages */ @@ -48,8 +50,11 @@ extern PGDLLIMPORT double random_page_cost; extern PGDLLIMPORT double cpu_tuple_cost; extern PGDLLIMPORT double cpu_index_tuple_cost; extern PGDLLIMPORT double cpu_operator_cost; +extern PGDLLIMPORT double parallel_tuple_cost; +extern PGDLLIMPORT double parallel_setup_cost; extern PGDLLIMPORT int effective_cache_size; extern Cost disable_cost; +extern int max_parallel_degree; extern bool enable_seqscan; extern bool enable_indexscan; extern bool enable_indexonlyscan; @@ -144,6 +149,8 @@ extern void final_cost_hashjoin(PlannerInfo *root, HashPath *path, JoinCostWorkspace *workspace, SpecialJoinInfo *sjinfo, SemiAntiJoinFactors *semifactors); +extern void cost_gather(GatherPath *path, PlannerInfo *root, + RelOptInfo *baserel, ParamPathInfo *param_info); extern void cost_subplan(PlannerInfo *root, SubPlan *subplan, Plan *plan); extern void cost_qual_eval(QualCost *cost, List *quals, PlannerInfo *root); extern void cost_qual_eval_node(QualCost *cost, Node *qual, PlannerInfo *root); diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h index 161644c343b..7a4940c7d20 100644 --- a/src/include/optimizer/pathnode.h +++ b/src/include/optimizer/pathnode.h @@ -69,6 +69,9 @@ extern ResultPath *create_result_path(List *quals); extern MaterialPath *create_material_path(RelOptInfo *rel, Path *subpath); extern UniquePath *create_unique_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, SpecialJoinInfo *sjinfo); +extern GatherPath *create_gather_path(PlannerInfo *root, + RelOptInfo *rel, Path *subpath, Relids required_outer, + int nworkers); extern Path *create_subqueryscan_path(PlannerInfo *root, RelOptInfo *rel, List *pathkeys, Relids required_outer); extern Path *create_functionscan_path(PlannerInfo *root, RelOptInfo *rel, |