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postgresql/src/include/optimizer/paths.h

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Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*-------------------------------------------------------------------------
*
Change my-function-name-- to my_function_name, and optimizer renames.
1999-02-14 00:22:53 +01:00
* paths.h
Correct bug in best_innerjoin(): it should check all the rels that the inner path needs to join to, but it was only checking for the first one. Failure could only have been observed with an OR-clause that mentions 3 or more tables, and then only if the bogus path was actually selected as cheapest ...
1999-07-27 08:23:12 +02:00
* prototypes for various files in optimizer/path (were separate
* header files)
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*
*
Tag appropriate files for rc3 Also performed an initial run through of upgrading our Copyright date to extend to 2005 ... first run here was very simple ... change everything where: grep 1996-2004 && the word 'Copyright' ... scanned through the generated list with 'less' first, and after, to make sure that I only picked up the right entries ...
2004-12-31 23:04:05 +01:00
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
Add: * Portions Copyright (c) 1996-2000, PostgreSQL, Inc to all files copyright Regents of Berkeley. Man, that's a lot of files.
2000-01-26 06:58:53 +01:00
* Portions Copyright (c) 1994, Regents of the University of California
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*
Add a back-link from IndexOptInfo structs to their parent RelOptInfo structs. There are many places in the planner where we were passing both a rel and an index to subroutines, and now need only pass the index struct. Notationally simpler, and perhaps a tad faster.
2005-03-27 08:29:49 +02:00
* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.80 2005/03/27 06:29:49 tgl Exp $
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*
*-------------------------------------------------------------------------
*/
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
#ifndef PATHS_H
#define PATHS_H
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
Cleanup up include files.
1997-11-26 02:14:33 +01:00
#include "nodes/relation.h"
Modify planner's implied-equality-deduction code so that when a set of known-equal expressions includes any constant expressions (including Params from outer queries), we actively suppress any 'var = var' clauses that are or could be deduced from the set, generating only the deducible 'var = const' clauses instead. The idea here is to push down the restrictions implied by the equality set to base relations whenever possible. Once we have applied the 'var = const' clauses, the 'var = var' clauses are redundant, and should be suppressed both to save work at execution and to avoid double-counting restrictivity.
2003-01-24 04:58:44 +01:00
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*
Correct bug in best_innerjoin(): it should check all the rels that the inner path needs to join to, but it was only checking for the first one. Failure could only have been observed with an OR-clause that mentions 3 or more tables, and then only if the bogus path was actually selected as cheapest ...
1999-07-27 08:23:12 +02:00
* allpaths.c
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*/
Revise handling of index-type-specific indexscan cost estimation, per pghackers discussion of 5-Jan-2000. The amopselect and amopnpages estimators are gone, and in their place is a per-AM amcostestimate procedure (linked to from pg_am, not pg_amop).
2000-01-23 00:50:30 +01:00
extern bool enable_geqo;
Allow the planner to collapse explicit inner JOINs together, rather than necessarily following the JOIN syntax to develop the query plan. The old behavior is still available by setting GUC variable JOIN_COLLAPSE_LIMIT to 1. Also create a GUC variable FROM_COLLAPSE_LIMIT to control the similar decision about when to collapse sub-SELECT lists into their parent lists. (This behavior existed already, but the limit was always GEQO_THRESHOLD/2; now it's separately adjustable.)
2003-01-26 00:10:30 +01:00
extern int geqo_threshold;
Revise handling of index-type-specific indexscan cost estimation, per pghackers discussion of 5-Jan-2000. The amopselect and amopnpages estimators are gone, and in their place is a per-AM amcostestimate procedure (linked to from pg_am, not pg_amop).
2000-01-23 00:50:30 +01:00
Repair planning bugs caused by my misguided removal of restrictinfo link fields in JoinPaths --- turns out that we do need that after all :-(. Also, rearrange planner so that only one RelOptInfo is created for a particular set of joined base relations, no matter how many different subsets of relations it can be created from. This saves memory and processing time compared to the old method of making a bunch of RelOptInfos and then removing the duplicates. Clean up the jointree iteration logic; not sure if it's better, but I sure find it more readable and plausible now, particularly for the case of 'bushy plans'.
2000-02-07 05:41:04 +01:00
extern RelOptInfo *make_one_rel(Query *root);
Subselects in FROM clause, per ISO syntax: FROM (SELECT ...) [AS] alias. (Don't forget that an alias is required.) Views reimplemented as expanding to subselect-in-FROM. Grouping, aggregates, DISTINCT in views actually work now (he says optimistically). No UNION support in subselects/views yet, but I have some ideas about that. Rule-related permissions checking moved out of rewriter and into executor. INITDB REQUIRED!
2000-09-29 20:21:41 +02:00
extern RelOptInfo *make_fromexpr_rel(Query *root, FromExpr *from);
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
Extend code that deduces implied equality clauses to detect whether a clause being added to a particular restriction-clause list is redundant with those already in the list. This avoids useless work at runtime, and (perhaps more importantly) keeps the selectivity estimation routines from generating too-small estimates of numbers of output rows. Also some minor improvements in OPTIMIZER_DEBUG displays.
2001-10-18 18:11:42 +02:00
#ifdef OPTIMIZER_DEBUG
extern void debug_print_rel(Query *root, RelOptInfo *rel);
#endif
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*
Correct bug in best_innerjoin(): it should check all the rels that the inner path needs to join to, but it was only checking for the first one. Failure could only have been observed with an OR-clause that mentions 3 or more tables, and then only if the bogus path was actually selected as cheapest ...
1999-07-27 08:23:12 +02:00
* indxpath.c
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
* routines to generate index paths
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*/
Modify optimizer data structures so that IndexOptInfo lists built for create_index_paths are not immediately discarded, but are available for subsequent planner work. This allows avoiding redundant syscache lookups in several places. Change interface to operator selectivity estimation procedures to allow faster and more flexible estimation. Initdb forced due to change of pg_proc entries for selectivity functions!
2001-05-20 22:28:20 +02:00
extern void create_index_paths(Query *root, RelOptInfo *rel);
Restructure planning of nestloop inner indexscans so that the set of usable joinclauses is determined accurately for each join. Formerly, the code only considered joinclauses that used all of the rels from the outer side of the join; thus for example FROM (a CROSS JOIN b) JOIN c ON (c.f1 = a.x AND c.f2 = b.y) could not exploit a two-column index on c(f1,f2), since neither of the qual clauses would be in the joininfo list it looked in. The new code does this correctly, and also is able to eliminate redundant clauses, thus fixing the problem noted 24-Oct-02 by Hans-Jürgen Schönig.
2002-11-24 22:52:15 +01:00
extern Path *best_inner_indexscan(Query *root, RelOptInfo *rel,
pgindent run.
2003-08-04 02:43:34 +02:00
Relids outer_relids, JoinType jointype);
Add a back-link from IndexOptInfo structs to their parent RelOptInfo structs. There are many places in the planner where we were passing both a rel and an index to subroutines, and now need only pass the index struct. Notationally simpler, and perhaps a tad faster.
2005-03-27 08:29:49 +02:00
extern List *group_clauses_by_indexkey_for_or(IndexOptInfo *index,
Pgindent run for 8.0.
2004-08-29 07:07:03 +02:00
Expr *orsubclause);
Add a back-link from IndexOptInfo structs to their parent RelOptInfo structs. There are many places in the planner where we were passing both a rel and an index to subroutines, and now need only pass the index struct. Notationally simpler, and perhaps a tad faster.
2005-03-27 08:29:49 +02:00
extern List *expand_indexqual_conditions(IndexOptInfo *index,
Expand the 'special index operator' machinery to handle special cases for boolean indexes. Previously we would only use such an index with WHERE clauses like 'indexkey = true' or 'indexkey = false'. The new code transforms the cases 'indexkey', 'NOT indexkey', 'indexkey IS TRUE', and 'indexkey IS FALSE' into one of these. While this is only marginally useful in itself, I intend soon to change constant-expression simplification so that 'foo = true' and 'foo = false' are reduced to just 'foo' and 'NOT foo' ... which would lose the ability to use boolean indexes for such queries at all, if the indexscan machinery couldn't make the reverse transformation.
2005-03-27 00:29:20 +01:00
List *clausegroups);
Add the ability to extract OR indexscan conditions from OR-of-AND join conditions in which each OR subclause includes a constraint on the same relation. This implements the other useful side-effect of conversion to CNF format, without its unpleasant side-effects. As per pghackers discussion of a few weeks ago.
2004-01-05 06:07:36 +01:00
extern void check_partial_indexes(Query *root, RelOptInfo *rel);
Fix OR-index-scan planner to recognize that a partial index is usable for scanning one term of an OR clause if the index's predicate is implied by that same OR clause term (possibly in conjunction with top-level WHERE clauses). Per recent example from Dawid Kuroczko, http://archives.postgresql.org/pgsql-performance/2004-10/msg00095.php Also, fix a very long-standing bug in index predicate testing, namely the bizarre ordering of decomposition of predicate and restriction clauses. AFAICS the correct way is to break down the predicate all the way, and then for each component term see if you can prove it from the entire restriction set. The original coding had a purely-implementation-artifact distinction between ANDing at the top level and ANDing below that, and proceeded to get the decomposition order wrong everywhere below the top level, with the result that even slightly complicated AND/OR predicates could not be proven. For instance, given create index foop on foo(f2) where f1=42 or f1=1 or (f1 = 11 and f2 = 55); the old code would fail to match this index to the query select * from foo where f1 = 11 and f2 = 55; when it obviously ought to match.
2004-10-12 00:57:00 +02:00
extern bool pred_test(List *predicate_list, List *restrictinfo_list);
Adjust indexscan planning logic to keep RestrictInfo nodes associated with index qual clauses in the Path representation. This saves a little work during createplan and (probably more importantly) allows reuse of cached selectivity estimates during indexscan planning. Also fix latent bug: wrong plan would have been generated for a 'special operator' used in a nestloop-inner-indexscan join qual, because the special operator would not have gotten into the list of quals to recheck. This bug is only latent because at present the special-operator code could never trigger on a join qual, but sooner or later someone will want to do it.
2004-01-06 00:39:54 +01:00
extern List *flatten_clausegroups_list(List *clausegroups);
extern Expr *make_expr_from_indexclauses(List *indexclauses);
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
Further cleanup for OR-of-AND WHERE-clauses. orindxpath can now handle extracting from an AND subclause just those opclauses that are relevant for a particular index. For example, we can now consider using an index on x to process WHERE (x = 1 AND y = 2) OR (x = 2 AND y = 4) OR ...
2000-02-05 19:26:09 +01:00
/*
* orindxpath.c
* additional routines for indexable OR clauses
*/
Add the ability to extract OR indexscan conditions from OR-of-AND join conditions in which each OR subclause includes a constraint on the same relation. This implements the other useful side-effect of conversion to CNF format, without its unpleasant side-effects. As per pghackers discussion of a few weeks ago.
2004-01-05 06:07:36 +01:00
extern bool create_or_index_quals(Query *root, RelOptInfo *rel);
Improve planning of OR indexscan plans: for quals like WHERE (a = 1 or a = 2) and b = 42 and an index on (a,b), include the clause b = 42 in the indexquals generated for each arm of the OR clause. Essentially this is an index- driven conversion from CNF to DNF. Implementation is a bit klugy, but better than not exploiting the extra quals at all ...
2001-06-05 19:13:52 +02:00
extern void create_or_index_paths(Query *root, RelOptInfo *rel);
Further cleanup for OR-of-AND WHERE-clauses. orindxpath can now handle extracting from an AND subclause just those opclauses that are relevant for a particular index. For example, we can now consider using an index on x to process WHERE (x = 1 AND y = 2) OR (x = 2 AND y = 4) OR ...
2000-02-05 19:26:09 +01:00
Tid access method feature from Hiroshi Inoue, Inoue@tpf.co.jp
1999-11-23 21:07:06 +01:00
/*
* tidpath.h
* routines to generate tid paths
*/
New cost model for planning, incorporating a penalty for random page accesses versus sequential accesses, a (very crude) estimate of the effects of caching on random page accesses, and cost to evaluate WHERE- clause expressions. Export critical parameters for this model as SET variables. Also, create SET variables for the planner's enable flags (enable_seqscan, enable_indexscan, etc) so that these can be controlled more conveniently than via PGOPTIONS. Planner now estimates both startup cost (cost before retrieving first tuple) and total cost of each path, so it can optimize queries with LIMIT on a reasonable basis by interpolating between these costs. Same facility is a win for EXISTS(...) subqueries and some other cases. Redesign pathkey representation to achieve a major speedup in planning (I saw as much as 5X on a 10-way join); also minor changes in planner to reduce memory consumption by recycling discarded Path nodes and not constructing unnecessary lists. Minor cleanups to display more-plausible costs in some cases in EXPLAIN output. Initdb forced by change in interface to index cost estimation functions.
2000-02-15 21:49:31 +01:00
extern void create_tidscan_paths(Query *root, RelOptInfo *rel);
Tid access method feature from Hiroshi Inoue, Inoue@tpf.co.jp
1999-11-23 21:07:06 +01:00
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*
Correct bug in best_innerjoin(): it should check all the rels that the inner path needs to join to, but it was only checking for the first one. Failure could only have been observed with an OR-clause that mentions 3 or more tables, and then only if the bogus path was actually selected as cheapest ...
1999-07-27 08:23:12 +02:00
* joinpath.c
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
* routines to create join paths
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*/
Repair planning bugs caused by my misguided removal of restrictinfo link fields in JoinPaths --- turns out that we do need that after all :-(. Also, rearrange planner so that only one RelOptInfo is created for a particular set of joined base relations, no matter how many different subsets of relations it can be created from. This saves memory and processing time compared to the old method of making a bunch of RelOptInfos and then removing the duplicates. Clean up the jointree iteration logic; not sure if it's better, but I sure find it more readable and plausible now, particularly for the case of 'bushy plans'.
2000-02-07 05:41:04 +01:00
extern void add_paths_to_joinrel(Query *root, RelOptInfo *joinrel,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
List *restrictlist);
Repair planning bugs caused by my misguided removal of restrictinfo link fields in JoinPaths --- turns out that we do need that after all :-(. Also, rearrange planner so that only one RelOptInfo is created for a particular set of joined base relations, no matter how many different subsets of relations it can be created from. This saves memory and processing time compared to the old method of making a bunch of RelOptInfos and then removing the duplicates. Clean up the jointree iteration logic; not sure if it's better, but I sure find it more readable and plausible now, particularly for the case of 'bushy plans'.
2000-02-07 05:41:04 +01:00
/*
* joinrels.c
* routines to determine which relations to join
*/
First cut at full support for OUTER JOINs. There are still a few loose ends to clean up (see my message of same date to pghackers), but mostly it works. INITDB REQUIRED!
2000-09-12 23:07:18 +02:00
extern List *make_rels_by_joins(Query *root, int level, List **joinrels);
Subselects in FROM clause, per ISO syntax: FROM (SELECT ...) [AS] alias. (Don't forget that an alias is required.) Views reimplemented as expanding to subselect-in-FROM. Grouping, aggregates, DISTINCT in views actually work now (he says optimistically). No UNION support in subselects/views yet, but I have some ideas about that. Rule-related permissions checking moved out of rewriter and into executor. INITDB REQUIRED!
2000-09-29 20:21:41 +02:00
extern RelOptInfo *make_jointree_rel(Query *root, Node *jtnode);
Fix GEQO to work again in CVS tip, by being more careful about memory allocation in best_inner_indexscan(). While at it, simplify GEQO's interface to the main planner --- make_join_rel() offers exactly the API it really wants, whereas calling make_rels_by_clause_joins() and make_rels_by_clauseless_joins() required jumping through hoops. Rewrite gimme_tree for clarity (sometimes iteration is much better than recursion), and approximately halve GEQO's runtime by recognizing that tours of the forms (a,b,c,d,...) and (b,a,c,d,...) are equivalent because of symmetry in make_join_rel().
2002-12-16 22:30:30 +01:00
extern RelOptInfo *make_join_rel(Query *root,
pgindent run.
2003-08-04 02:43:34 +02:00
RelOptInfo *rel1, RelOptInfo *rel2,
JoinType jointype);
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*
Major planner/optimizer revision: get rid of PathOrder node type, store all ordering information in pathkeys lists (which are now lists of lists of PathKeyItem nodes, not just lists of lists of vars). This was a big win --- the code is smaller and IMHO more understandable than it was, even though it handles more cases. I believe the node changes will not force an initdb for anyone; planner nodes don't show up in stored rules.
1999-08-16 04:17:58 +02:00
* pathkeys.c
* utilities for matching and building path keys
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*/
Major planner/optimizer revision: get rid of PathOrder node type, store all ordering information in pathkeys lists (which are now lists of lists of PathKeyItem nodes, not just lists of lists of vars). This was a big win --- the code is smaller and IMHO more understandable than it was, even though it handles more cases. I believe the node changes will not force an initdb for anyone; planner nodes don't show up in stored rules.
1999-08-16 04:17:58 +02:00
typedef enum
{
Another pgindent run. Fixes enum indenting, and improves #endif spacing. Also adds space for one-line comments.
2001-10-28 07:26:15 +01:00
PATHKEYS_EQUAL, /* pathkeys are identical */
PATHKEYS_BETTER1, /* pathkey 1 is a superset of pathkey 2 */
PATHKEYS_BETTER2, /* vice versa */
PATHKEYS_DIFFERENT /* neither pathkey includes the other */
Major planner/optimizer revision: get rid of PathOrder node type, store all ordering information in pathkeys lists (which are now lists of lists of PathKeyItem nodes, not just lists of lists of vars). This was a big win --- the code is smaller and IMHO more understandable than it was, even though it handles more cases. I believe the node changes will not force an initdb for anyone; planner nodes don't show up in stored rules.
1999-08-16 04:17:58 +02:00
} PathKeysComparison;
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
New cost model for planning, incorporating a penalty for random page accesses versus sequential accesses, a (very crude) estimate of the effects of caching on random page accesses, and cost to evaluate WHERE- clause expressions. Export critical parameters for this model as SET variables. Also, create SET variables for the planner's enable flags (enable_seqscan, enable_indexscan, etc) so that these can be controlled more conveniently than via PGOPTIONS. Planner now estimates both startup cost (cost before retrieving first tuple) and total cost of each path, so it can optimize queries with LIMIT on a reasonable basis by interpolating between these costs. Same facility is a win for EXISTS(...) subqueries and some other cases. Redesign pathkey representation to achieve a major speedup in planning (I saw as much as 5X on a 10-way join); also minor changes in planner to reduce memory consumption by recycling discarded Path nodes and not constructing unnecessary lists. Minor cleanups to display more-plausible costs in some cases in EXPLAIN output. Initdb forced by change in interface to index cost estimation functions.
2000-02-15 21:49:31 +01:00
extern void add_equijoined_keys(Query *root, RestrictInfo *restrictinfo);
Modify planner's implied-equality-deduction code so that when a set of known-equal expressions includes any constant expressions (including Params from outer queries), we actively suppress any 'var = var' clauses that are or could be deduced from the set, generating only the deducible 'var = const' clauses instead. The idea here is to push down the restrictions implied by the equality set to base relations whenever possible. Once we have applied the 'var = const' clauses, the 'var = var' clauses are redundant, and should be suppressed both to save work at execution and to avoid double-counting restrictivity.
2003-01-24 04:58:44 +01:00
extern bool exprs_known_equal(Query *root, Node *item1, Node *item2);
Deduce equality constraints that are implied by transitivity of mergejoinable qual clauses, and add them to the query quals. For example, WHERE a = b AND b = c will cause us to add AND a = c. This is necessary to ensure that it's safe to use these variables as interchangeable sort keys, which is something 7.0 knows how to do. Should provide a useful improvement in planning ability, too.
2000-07-24 05:11:01 +02:00
extern void generate_implied_equalities(Query *root);
New cost model for planning, incorporating a penalty for random page accesses versus sequential accesses, a (very crude) estimate of the effects of caching on random page accesses, and cost to evaluate WHERE- clause expressions. Export critical parameters for this model as SET variables. Also, create SET variables for the planner's enable flags (enable_seqscan, enable_indexscan, etc) so that these can be controlled more conveniently than via PGOPTIONS. Planner now estimates both startup cost (cost before retrieving first tuple) and total cost of each path, so it can optimize queries with LIMIT on a reasonable basis by interpolating between these costs. Same facility is a win for EXISTS(...) subqueries and some other cases. Redesign pathkey representation to achieve a major speedup in planning (I saw as much as 5X on a 10-way join); also minor changes in planner to reduce memory consumption by recycling discarded Path nodes and not constructing unnecessary lists. Minor cleanups to display more-plausible costs in some cases in EXPLAIN output. Initdb forced by change in interface to index cost estimation functions.
2000-02-15 21:49:31 +01:00
extern List *canonicalize_pathkeys(Query *root, List *pathkeys);
Major planner/optimizer revision: get rid of PathOrder node type, store all ordering information in pathkeys lists (which are now lists of lists of PathKeyItem nodes, not just lists of lists of vars). This was a big win --- the code is smaller and IMHO more understandable than it was, even though it handles more cases. I believe the node changes will not force an initdb for anyone; planner nodes don't show up in stored rules.
1999-08-16 04:17:58 +02:00
extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
extern bool pathkeys_contained_in(List *keys1, List *keys2);
Planner speedup hacking. Avoid saving useless pathkeys, so that path comparison does not consider paths different when they differ only in uninteresting aspects of sort order. (We had a special case of this consideration for indexscans already, but generalize it to apply to ordered join paths too.) Be stricter about what is a canonical pathkey to allow faster pathkey comparison. Cache canonical pathkeys and dispersion stats for left and right sides of a RestrictInfo's clause, to avoid repeated computation. Total speedup will depend on number of tables in a query, but I see about 4x speedup of planning phase for a sample seven-table query.
2000-12-14 23:30:45 +01:00
extern PathKeysComparison compare_noncanonical_pathkeys(List *keys1,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
List *keys2);
Planner speedup hacking. Avoid saving useless pathkeys, so that path comparison does not consider paths different when they differ only in uninteresting aspects of sort order. (We had a special case of this consideration for indexscans already, but generalize it to apply to ordered join paths too.) Be stricter about what is a canonical pathkey to allow faster pathkey comparison. Cache canonical pathkeys and dispersion stats for left and right sides of a RestrictInfo's clause, to avoid repeated computation. Total speedup will depend on number of tables in a query, but I see about 4x speedup of planning phase for a sample seven-table query.
2000-12-14 23:30:45 +01:00
extern bool noncanonical_pathkeys_contained_in(List *keys1, List *keys2);
Major revision of sort-node handling: push knowledge of query sort order down into planner, instead of handling it only at the very top level of the planner. This fixes many things. An explicit sort is now avoided if there is a cheaper alternative (typically an indexscan) not only for ORDER BY, but also for the internal sort of GROUP BY. It works even when there is no other reason (such as a WHERE condition) to consider the indexscan. It works for indexes on functions. It works for indexes on functions, backwards. It's just so cool... CAUTION: I have changed the representation of SortClause nodes, therefore THIS UPDATE BREAKS STORED RULES. You will need to initdb.
1999-08-21 05:49:17 +02:00
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
CostSelector cost_criterion);
New cost model for planning, incorporating a penalty for random page accesses versus sequential accesses, a (very crude) estimate of the effects of caching on random page accesses, and cost to evaluate WHERE- clause expressions. Export critical parameters for this model as SET variables. Also, create SET variables for the planner's enable flags (enable_seqscan, enable_indexscan, etc) so that these can be controlled more conveniently than via PGOPTIONS. Planner now estimates both startup cost (cost before retrieving first tuple) and total cost of each path, so it can optimize queries with LIMIT on a reasonable basis by interpolating between these costs. Same facility is a win for EXISTS(...) subqueries and some other cases. Redesign pathkey representation to achieve a major speedup in planning (I saw as much as 5X on a 10-way join); also minor changes in planner to reduce memory consumption by recycling discarded Path nodes and not constructing unnecessary lists. Minor cleanups to display more-plausible costs in some cases in EXPLAIN output. Initdb forced by change in interface to index cost estimation functions.
2000-02-15 21:49:31 +01:00
extern Path *get_cheapest_fractional_path_for_pathkeys(List *paths,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
List *pathkeys,
double fraction);
Add a back-link from IndexOptInfo structs to their parent RelOptInfo structs. There are many places in the planner where we were passing both a rel and an index to subroutines, and now need only pass the index struct. Notationally simpler, and perhaps a tad faster.
2005-03-27 08:29:49 +02:00
extern List *build_index_pathkeys(Query *root, IndexOptInfo *index,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
ScanDirection scandir);
Teach planner how to propagate pathkeys from sub-SELECTs in FROM up to the outer query. (The implementation is a bit klugy, but it would take nontrivial restructuring to make it nicer, which this is probably not worth.) This avoids unnecessary sort steps in examples like SELECT foo,count(*) FROM (SELECT ... ORDER BY foo,bar) sub GROUP BY foo which means there is now a reasonable technique for controlling the order of inputs to custom aggregates, even in the grouping case.
2003-02-15 21:12:41 +01:00
extern List *build_subquery_pathkeys(Query *root, RelOptInfo *rel,
pgindent run.
2003-08-04 02:43:34 +02:00
Query *subquery);
Planner speedup hacking. Avoid saving useless pathkeys, so that path comparison does not consider paths different when they differ only in uninteresting aspects of sort order. (We had a special case of this consideration for indexscans already, but generalize it to apply to ordered join paths too.) Be stricter about what is a canonical pathkey to allow faster pathkey comparison. Cache canonical pathkeys and dispersion stats for left and right sides of a RestrictInfo's clause, to avoid repeated computation. Total speedup will depend on number of tables in a query, but I see about 4x speedup of planning phase for a sample seven-table query.
2000-12-14 23:30:45 +01:00
extern List *build_join_pathkeys(Query *root,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
RelOptInfo *joinrel,
The result of a FULL or RIGHT join can't be assumed to be sorted by the left input's sorting, because null rows may be inserted at various points. Per report from Ferenc Lutischá¸n.
2005-01-23 03:21:36 +01:00
JoinType jointype,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
List *outer_pathkeys);
Major revision of sort-node handling: push knowledge of query sort order down into planner, instead of handling it only at the very top level of the planner. This fixes many things. An explicit sort is now avoided if there is a cheaper alternative (typically an indexscan) not only for ORDER BY, but also for the internal sort of GROUP BY. It works even when there is no other reason (such as a WHERE condition) to consider the indexscan. It works for indexes on functions. It works for indexes on functions, backwards. It's just so cool... CAUTION: I have changed the representation of SortClause nodes, therefore THIS UPDATE BREAKS STORED RULES. You will need to initdb.
1999-08-21 05:49:17 +02:00
extern List *make_pathkeys_for_sortclauses(List *sortclauses,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
List *tlist);
Extend code that deduces implied equality clauses to detect whether a clause being added to a particular restriction-clause list is redundant with those already in the list. This avoids useless work at runtime, and (perhaps more importantly) keeps the selectivity estimation routines from generating too-small estimates of numbers of output rows. Also some minor improvements in OPTIMIZER_DEBUG displays.
2001-10-18 18:11:42 +02:00
extern void cache_mergeclause_pathkeys(Query *root,
pgindent run on all C files. Java run to follow. initdb/regression tests pass.
2001-10-25 07:50:21 +02:00
RestrictInfo *restrictinfo);
Planner speedup hacking. Avoid saving useless pathkeys, so that path comparison does not consider paths different when they differ only in uninteresting aspects of sort order. (We had a special case of this consideration for indexscans already, but generalize it to apply to ordered join paths too.) Be stricter about what is a canonical pathkey to allow faster pathkey comparison. Cache canonical pathkeys and dispersion stats for left and right sides of a RestrictInfo's clause, to avoid repeated computation. Total speedup will depend on number of tables in a query, but I see about 4x speedup of planning phase for a sample seven-table query.
2000-12-14 23:30:45 +01:00
extern List *find_mergeclauses_for_pathkeys(Query *root,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
List *pathkeys,
List *restrictinfos);
New cost model for planning, incorporating a penalty for random page accesses versus sequential accesses, a (very crude) estimate of the effects of caching on random page accesses, and cost to evaluate WHERE- clause expressions. Export critical parameters for this model as SET variables. Also, create SET variables for the planner's enable flags (enable_seqscan, enable_indexscan, etc) so that these can be controlled more conveniently than via PGOPTIONS. Planner now estimates both startup cost (cost before retrieving first tuple) and total cost of each path, so it can optimize queries with LIMIT on a reasonable basis by interpolating between these costs. Same facility is a win for EXISTS(...) subqueries and some other cases. Redesign pathkey representation to achieve a major speedup in planning (I saw as much as 5X on a 10-way join); also minor changes in planner to reduce memory consumption by recycling discarded Path nodes and not constructing unnecessary lists. Minor cleanups to display more-plausible costs in some cases in EXPLAIN output. Initdb forced by change in interface to index cost estimation functions.
2000-02-15 21:49:31 +01:00
extern List *make_pathkeys_for_mergeclauses(Query *root,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
List *mergeclauses,
RelOptInfo *rel);
extern int pathkeys_useful_for_merging(Query *root,
RelOptInfo *rel,
List *pathkeys);
Planner speedup hacking. Avoid saving useless pathkeys, so that path comparison does not consider paths different when they differ only in uninteresting aspects of sort order. (We had a special case of this consideration for indexscans already, but generalize it to apply to ordered join paths too.) Be stricter about what is a canonical pathkey to allow faster pathkey comparison. Cache canonical pathkeys and dispersion stats for left and right sides of a RestrictInfo's clause, to avoid repeated computation. Total speedup will depend on number of tables in a query, but I see about 4x speedup of planning phase for a sample seven-table query.
2000-12-14 23:30:45 +01:00
extern int pathkeys_useful_for_ordering(Query *root, List *pathkeys);
extern List *truncate_useless_pathkeys(Query *root,
pgindent run. Make it all clean.
2001-03-22 05:01:46 +01:00
RelOptInfo *rel,
List *pathkeys);
Another pgindent run. Fixes enum indenting, and improves #endif spacing. Also adds space for one-line comments.
2001-10-28 07:26:15 +01:00
New pgindent run with fixes suggested by Tom. Patch manually reviewed, initdb/regression tests pass.
2001-11-05 18:46:40 +01:00
#endif /* PATHS_H */