mirror of
https://git.postgresql.org/git/postgresql.git
synced 2026-02-16 03:17:00 +08:00
355d3993c5
Like Gather, we spawn multiple workers and run the same plan in each one; however, Gather Merge is used when each worker produces the same output ordering and we want to preserve that output ordering while merging together the streams of tuples from various workers. (In a way, Gather Merge is like a hybrid of Gather and MergeAppend.) This works out to a win if it saves us from having to perform an expensive Sort. In cases where only a small amount of data would need to be sorted, it may actually be faster to use a regular Gather node and then sort the results afterward, because Gather Merge sometimes needs to wait synchronously for tuples whereas a pure Gather generally doesn't. But if this avoids an expensive sort then it's a win. Rushabh Lathia, reviewed and tested by Amit Kapila, Thomas Munro, and Neha Sharma, and reviewed and revised by me. Discussion: http://postgr.es/m/CAGPqQf09oPX-cQRpBKS0Gq49Z+m6KBxgxd_p9gX8CKk_d75HoQ@mail.gmail.com
215 lines
8.7 KiB
C
215 lines
8.7 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* cost.h
|
|
* prototypes for costsize.c and clausesel.c.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/optimizer/cost.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef COST_H
|
|
#define COST_H
|
|
|
|
#include "nodes/plannodes.h"
|
|
#include "nodes/relation.h"
|
|
|
|
|
|
/* defaults for costsize.c's Cost parameters */
|
|
/* NB: cost-estimation code should use the variables, not these constants! */
|
|
/* If you change these, update backend/utils/misc/postgresql.sample.conf */
|
|
#define DEFAULT_SEQ_PAGE_COST 1.0
|
|
#define DEFAULT_RANDOM_PAGE_COST 4.0
|
|
#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 */
|
|
|
|
typedef enum
|
|
{
|
|
CONSTRAINT_EXCLUSION_OFF, /* do not use c_e */
|
|
CONSTRAINT_EXCLUSION_ON, /* apply c_e to all rels */
|
|
CONSTRAINT_EXCLUSION_PARTITION /* apply c_e to otherrels only */
|
|
} ConstraintExclusionType;
|
|
|
|
|
|
/*
|
|
* prototypes for costsize.c
|
|
* routines to compute costs and sizes
|
|
*/
|
|
|
|
/* parameter variables and flags */
|
|
extern PGDLLIMPORT double seq_page_cost;
|
|
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_workers_per_gather;
|
|
extern bool enable_seqscan;
|
|
extern bool enable_indexscan;
|
|
extern bool enable_indexonlyscan;
|
|
extern bool enable_bitmapscan;
|
|
extern bool enable_tidscan;
|
|
extern bool enable_sort;
|
|
extern bool enable_hashagg;
|
|
extern bool enable_nestloop;
|
|
extern bool enable_material;
|
|
extern bool enable_mergejoin;
|
|
extern bool enable_hashjoin;
|
|
extern bool enable_gathermerge;
|
|
extern int constraint_exclusion;
|
|
|
|
extern double clamp_row_est(double nrows);
|
|
extern double index_pages_fetched(double tuples_fetched, BlockNumber pages,
|
|
double index_pages, PlannerInfo *root);
|
|
extern void cost_seqscan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
|
|
ParamPathInfo *param_info);
|
|
extern void cost_samplescan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
|
|
ParamPathInfo *param_info);
|
|
extern void cost_index(IndexPath *path, PlannerInfo *root,
|
|
double loop_count, bool partial_path);
|
|
extern void cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
|
|
ParamPathInfo *param_info,
|
|
Path *bitmapqual, double loop_count);
|
|
extern void cost_bitmap_and_node(BitmapAndPath *path, PlannerInfo *root);
|
|
extern void cost_bitmap_or_node(BitmapOrPath *path, PlannerInfo *root);
|
|
extern void cost_bitmap_tree_node(Path *path, Cost *cost, Selectivity *selec);
|
|
extern void cost_tidscan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, List *tidquals, ParamPathInfo *param_info);
|
|
extern void cost_subqueryscan(SubqueryScanPath *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_functionscan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_tableexprscan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_valuesscan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_tablefuncscan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_ctescan(Path *path, PlannerInfo *root,
|
|
RelOptInfo *baserel, ParamPathInfo *param_info);
|
|
extern void cost_recursive_union(Path *runion, Path *nrterm, Path *rterm);
|
|
extern void cost_sort(Path *path, PlannerInfo *root,
|
|
List *pathkeys, Cost input_cost, double tuples, int width,
|
|
Cost comparison_cost, int sort_mem,
|
|
double limit_tuples);
|
|
extern void cost_merge_append(Path *path, PlannerInfo *root,
|
|
List *pathkeys, int n_streams,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double tuples);
|
|
extern void cost_material(Path *path,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double tuples, int width);
|
|
extern void cost_agg(Path *path, PlannerInfo *root,
|
|
AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
|
|
int numGroupCols, double numGroups,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double input_tuples);
|
|
extern void cost_windowagg(Path *path, PlannerInfo *root,
|
|
List *windowFuncs, int numPartCols, int numOrderCols,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double input_tuples);
|
|
extern void cost_group(Path *path, PlannerInfo *root,
|
|
int numGroupCols, double numGroups,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double input_tuples);
|
|
extern void initial_cost_nestloop(PlannerInfo *root,
|
|
JoinCostWorkspace *workspace,
|
|
JoinType jointype,
|
|
Path *outer_path, Path *inner_path,
|
|
SpecialJoinInfo *sjinfo,
|
|
SemiAntiJoinFactors *semifactors);
|
|
extern void final_cost_nestloop(PlannerInfo *root, NestPath *path,
|
|
JoinCostWorkspace *workspace,
|
|
SpecialJoinInfo *sjinfo,
|
|
SemiAntiJoinFactors *semifactors);
|
|
extern void initial_cost_mergejoin(PlannerInfo *root,
|
|
JoinCostWorkspace *workspace,
|
|
JoinType jointype,
|
|
List *mergeclauses,
|
|
Path *outer_path, Path *inner_path,
|
|
List *outersortkeys, List *innersortkeys,
|
|
SpecialJoinInfo *sjinfo);
|
|
extern void final_cost_mergejoin(PlannerInfo *root, MergePath *path,
|
|
JoinCostWorkspace *workspace,
|
|
SpecialJoinInfo *sjinfo);
|
|
extern void initial_cost_hashjoin(PlannerInfo *root,
|
|
JoinCostWorkspace *workspace,
|
|
JoinType jointype,
|
|
List *hashclauses,
|
|
Path *outer_path, Path *inner_path,
|
|
SpecialJoinInfo *sjinfo,
|
|
SemiAntiJoinFactors *semifactors);
|
|
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, double *rows);
|
|
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);
|
|
extern void compute_semi_anti_join_factors(PlannerInfo *root,
|
|
RelOptInfo *outerrel,
|
|
RelOptInfo *innerrel,
|
|
JoinType jointype,
|
|
SpecialJoinInfo *sjinfo,
|
|
List *restrictlist,
|
|
SemiAntiJoinFactors *semifactors);
|
|
extern void set_baserel_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern double get_parameterized_baserel_size(PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
List *param_clauses);
|
|
extern double get_parameterized_joinrel_size(PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
Path *outer_path,
|
|
Path *inner_path,
|
|
SpecialJoinInfo *sjinfo,
|
|
List *restrict_clauses);
|
|
extern void set_joinrel_size_estimates(PlannerInfo *root, RelOptInfo *rel,
|
|
RelOptInfo *outer_rel,
|
|
RelOptInfo *inner_rel,
|
|
SpecialJoinInfo *sjinfo,
|
|
List *restrictlist);
|
|
extern void set_subquery_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern void set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern void set_values_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern void set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel,
|
|
double cte_rows);
|
|
extern void set_tablefunc_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
|
|
extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
|
|
extern double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
|
|
Path *bitmapqual, int loop_count, Cost *cost, double *tuple);
|
|
|
|
/*
|
|
* prototypes for clausesel.c
|
|
* routines to compute clause selectivities
|
|
*/
|
|
extern Selectivity clauselist_selectivity(PlannerInfo *root,
|
|
List *clauses,
|
|
int varRelid,
|
|
JoinType jointype,
|
|
SpecialJoinInfo *sjinfo);
|
|
extern Selectivity clause_selectivity(PlannerInfo *root,
|
|
Node *clause,
|
|
int varRelid,
|
|
JoinType jointype,
|
|
SpecialJoinInfo *sjinfo);
|
|
extern void cost_gather_merge(GatherMergePath *path, PlannerInfo *root,
|
|
RelOptInfo *rel, ParamPathInfo *param_info,
|
|
Cost input_startup_cost, Cost input_total_cost,
|
|
double *rows);
|
|
|
|
#endif /* COST_H */
|