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postgresql/src/include/optimizer/cost.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
* cost.h
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
* prototypes for costsize.c and clausesel.c.
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*
*
Update copyright for 2016 Backpatch certain files through 9.1
2016-01-02 19:33:40 +01:00
* Portions Copyright (c) 1996-2016, 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
*
Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00
* src/include/optimizer/cost.h
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*
*-------------------------------------------------------------------------
*/
#ifndef COST_H
#define COST_H
Finish implementation of hashed aggregation. Add enable_hashagg GUC parameter to allow it to be forced off for comparison purposes. Add ORDER BY clauses to a bunch of regression test queries that will otherwise produce randomly-ordered output in the new regime.
2002-11-21 01:42:20 +01:00
#include "nodes/plannodes.h"
Cleanup up include files.
1997-11-26 02:14:33 +01:00
#include "nodes/relation.h"
Finish implementation of hashed aggregation. Add enable_hashagg GUC parameter to allow it to be forced off for comparison purposes. Add ORDER BY clauses to a bunch of regression test queries that will otherwise produce randomly-ordered output in the new regime.
2002-11-21 01:42:20 +01:00
First cut at unifying regular selectivity estimation with indexscan selectivity estimation wasn't right. This is better...
2000-01-23 03:07:00 +01:00
/* defaults for costsize.c's Cost parameters */
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
/* NB: cost-estimation code should use the variables, not these constants! */
Add all possible config file options.
2001-01-24 19:37:31 +01:00
/* If you change these, update backend/utils/misc/postgresql.sample.conf */
Add a GUC parameter seq_page_cost, and use that everywhere we formerly assumed that a sequential page fetch has cost 1.0. This patch doesn't in itself change the system's behavior at all, but it opens the door to people adopting other units of measurement for EXPLAIN costs. Also, if we ever decide it's worth inventing per-tablespace access cost settings, this change provides a workable intellectual framework for that.
2006-06-05 04:49:58 +02:00
#define DEFAULT_SEQ_PAGE_COST 1.0
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
#define DEFAULT_RANDOM_PAGE_COST 4.0
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
#define DEFAULT_CPU_TUPLE_COST 0.01
Increase the default value of cpu_index_tuple_cost from 0.001 to 0.005. This shouldn't affect simple indexscans much, while for bitmap scans that are touching a lot of index rows, this seems to bring the estimates more in line with reality. Per recent discussion.
2006-06-05 05:03:42 +02:00
#define DEFAULT_CPU_INDEX_TUPLE_COST 0.005
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
#define DEFAULT_CPU_OPERATOR_COST 0.0025
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.
2015-10-01 01:23:36 +02:00
#define DEFAULT_PARALLEL_TUPLE_COST 0.1
#define DEFAULT_PARALLEL_SETUP_COST 1000.0
First cut at unifying regular selectivity estimation with indexscan selectivity estimation wasn't right. This is better...
2000-01-23 03:07:00 +01:00
Increase the default value of effective_cache_size to 4GB. Per discussion, the old value of 128MB is ridiculously small on modern machines; in fact, it's not even any larger than the default value of shared_buffers, which it certainly should be. Increase to 4GB, which is unlikely to be any worse than the old default for anyone, and should be noticeably better for most. Eventually we might have an autotuning scheme for this setting, but the recent attempt crashed and burned, so for now just do this.
2014-05-09 03:11:47 +02:00
#define DEFAULT_EFFECTIVE_CACHE_SIZE 524288 /* measured in pages */
Revert "Auto-tune effective_cache size to be 4x shared buffers" This reverts commit ee1e5662d8d8330726eaef7d3110cb7add24d058, as well as a remarkably large number of followup commits, which were mostly concerned with the fact that the implementation didn't work terribly well. It still doesn't: we probably need some rather basic work in the GUC infrastructure if we want to fully support GUCs whose default varies depending on the value of another GUC. Meanwhile, it also emerged that there wasn't really consensus in favor of the definition the patch tried to implement (ie, effective_cache_size should default to 4 times shared_buffers). So whack it all back to where it was. In a followup commit, I'll do what was recently agreed to, which is to simply change the default to a higher value.
2014-05-09 02:49:38 +02:00
Create a third option named "partition" for constraint_exclusion, and make it the default. This setting enables constraint exclusion checks only for appendrel members (ie, inheritance children and UNION ALL arms), which are the cases in which constraint exclusion is most likely to be useful. Avoiding the overhead for simple queries that are unlikely to benefit should bring the cost down to the point where this is a reasonable default setting. Per today's discussion.
2009-01-07 23:40:49 +01:00
typedef enum
{
8.4 pgindent run, with new combined Linux/FreeBSD/MinGW typedef list provided by Andrew.
2009-06-11 16:49:15 +02:00
CONSTRAINT_EXCLUSION_OFF, /* do not use c_e */
CONSTRAINT_EXCLUSION_ON, /* apply c_e to all rels */
Create a third option named "partition" for constraint_exclusion, and make it the default. This setting enables constraint exclusion checks only for appendrel members (ie, inheritance children and UNION ALL arms), which are the cases in which constraint exclusion is most likely to be useful. Avoiding the overhead for simple queries that are unlikely to benefit should bring the cost down to the point where this is a reasonable default setting. Per today's discussion.
2009-01-07 23:40:49 +01:00
CONSTRAINT_EXCLUSION_PARTITION /* apply c_e to otherrels only */
pgindent run before PG 9.1 beta 1.
2011-04-10 17:42:00 +02:00
} ConstraintExclusionType;
Create a third option named "partition" for constraint_exclusion, and make it the default. This setting enables constraint exclusion checks only for appendrel members (ie, inheritance children and UNION ALL arms), which are the cases in which constraint exclusion is most likely to be useful. Avoiding the overhead for simple queries that are unlikely to benefit should bring the cost down to the point where this is a reasonable default setting. Per today's discussion.
2009-01-07 23:40:49 +01:00
Clean up #include in /include directory. Add scripts for checking includes.
1999-07-15 17:21:54 +02:00
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
* prototypes for costsize.c
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
* routines to compute costs and sizes
*/
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
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
/* parameter variables and flags */
Rename DLLIMPORT macro to PGDLLIMPORT to avoid conflict with third party includes (like tcl) that define DLLIMPORT.
2007-07-25 14:22:54 +02:00
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;
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.
2015-10-01 01:23:36 +02:00
extern PGDLLIMPORT double parallel_tuple_cost;
extern PGDLLIMPORT double parallel_setup_cost;
Rename DLLIMPORT macro to PGDLLIMPORT to avoid conflict with third party includes (like tcl) that define DLLIMPORT.
2007-07-25 14:22:54 +02:00
extern PGDLLIMPORT int effective_cache_size;
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 Cost disable_cost;
Eliminate "parallel degree" terminology. This terminology provoked widespread complaints. So, instead, rename the GUC max_parallel_degree to max_parallel_workers_per_gather (leaving room for a possible future GUC max_parallel_workers that acts as a system-wide limit), and rename the parallel_degree reloption to parallel_workers. Rename structure members to match. These changes create a dump/restore hazard for users of PostgreSQL 9.6beta1 who have set the reloption (or applied the GUC using ALTER USER or ALTER DATABASE).
2016-06-09 15:08:27 +02:00
extern int max_parallel_workers_per_gather;
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_seqscan;
extern bool enable_indexscan;
Support index-only scans using the visibility map to avoid heap fetches. When a btree index contains all columns required by the query, and the visibility map shows that all tuples on a target heap page are visible-to-all, we don't need to fetch that heap page. This patch depends on the previous patches that made the visibility map reliable. There's a fair amount left to do here, notably trying to figure out a less chintzy way of estimating the cost of an index-only scan, but the core functionality seems ready to commit. Robert Haas and Ibrar Ahmed, with some previous work by Heikki Linnakangas.
2011-10-08 02:13:02 +02:00
extern bool enable_indexonlyscan;
Rethink original decision to use AND/OR Expr nodes to represent bitmap logic operations during planning. Seems cleaner to create two new Path node types, instead --- this avoids duplication of cost-estimation code. Also, create an enable_bitmapscan GUC parameter to control use of bitmap plans.
2005-04-21 21:18:13 +02:00
extern bool enable_bitmapscan;
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_tidscan;
extern bool enable_sort;
Finish implementation of hashed aggregation. Add enable_hashagg GUC parameter to allow it to be forced off for comparison purposes. Add ORDER BY clauses to a bunch of regression test queries that will otherwise produce randomly-ordered output in the new regime.
2002-11-21 01:42:20 +01:00
extern bool enable_hashagg;
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_nestloop;
Add an 'enable_material' GUC. The logic for determining whether to materialize has been significantly overhauled for 9.0. In case there should be any doubt about whether materialization is a win in any particular case, this should provide a convenient way of seeing what happens without it; but even with enable_material turned off, we still materialize in cases where it is required for correctness. Thanks to Tom Lane for the review.
2010-04-19 02:55:26 +02:00
extern bool enable_material;
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_mergejoin;
extern bool enable_hashjoin;
Create a third option named "partition" for constraint_exclusion, and make it the default. This setting enables constraint exclusion checks only for appendrel members (ie, inheritance children and UNION ALL arms), which are the cases in which constraint exclusion is most likely to be useful. Avoiding the overhead for simple queries that are unlikely to benefit should bring the cost down to the point where this is a reasonable default setting. Per today's discussion.
2009-01-07 23:40:49 +01:00
extern int constraint_exclusion;
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
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 double clamp_row_est(double nrows);
Make the planner estimate costs for nestloop inner indexscans on the basis that the Mackert-Lohmann formula applies across all the repetitions of the nestloop, not just each scan independently. We use the M-L formula to estimate the number of pages fetched from the index as well as from the table; that isn't what it was designed for, but it seems reasonably applicable anyway. This makes large numbers of repetitions look much cheaper than before, which accords with many reports we've received of overestimation of the cost of a nestloop. Also, change the index access cost model to charge random_page_cost per index leaf page touched, while explicitly not counting anything for access to metapage or upper tree pages. This may all need tweaking after we get some field experience, but in simple tests it seems to be giving saner results than before. The main thing is to get the infrastructure in place to let cost_index() and amcostestimate functions take repeated scans into account at all. Per my recent proposal. Note: this patch changes pg_proc.h, but I did not force initdb because the changes are basically cosmetic --- the system does not look into pg_proc to decide how to call an index amcostestimate function, and there's no way to call such a function from SQL at all.
2006-06-06 19:59:58 +02:00
extern double index_pages_fetched(double tuples_fetched, BlockNumber pages,
pgindent run for 8.2.
2006-10-04 02:30:14 +02:00
double index_pages, PlannerInfo *root);
Revise parameterized-path mechanism to fix assorted issues. This patch adjusts the treatment of parameterized paths so that all paths with the same parameterization (same set of required outer rels) for the same relation will have the same rowcount estimate. We cache the rowcount estimates to ensure that property, and hopefully save a few cycles too. Doing this makes it practical for add_path_precheck to operate without a rowcount estimate: it need only assume that paths with different parameterizations never dominate each other, which is close enough to true anyway for coarse filtering, because normally a more-parameterized path should yield fewer rows thanks to having more join clauses to apply. In add_path, we do the full nine yards of comparing rowcount estimates along with everything else, so that we can discard parameterized paths that don't actually have an advantage. This fixes some issues I'd found with add_path rejecting parameterized paths on the grounds that they were more expensive than not-parameterized ones, even though they yielded many fewer rows and hence would be cheaper once subsequent joining was considered. To make the same-rowcounts assumption valid, we have to require that any parameterized path enforce *all* join clauses that could be obtained from the particular set of outer rels, even if not all of them are useful for indexing. This is required at both base scans and joins. It's a good thing anyway since the net impact is that join quals are checked at the lowest practical level in the join tree. Hence, discard the original rather ad-hoc mechanism for choosing parameterization joinquals, and build a better one that has a more principled rule for when clauses can be moved. The original rule was actually buggy anyway for lack of knowledge about which relations are part of an outer join's outer side; getting this right requires adding an outer_relids field to RestrictInfo.
2012-04-19 21:52:46 +02:00
extern void cost_seqscan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
Support parallel joins, and make related improvements. The core innovation of this patch is the introduction of the concept of a partial path; that is, a path which if executed in parallel will generate a subset of the output rows in each process. Gathering a partial path produces an ordinary (complete) path. This allows us to generate paths for parallel joins by joining a partial path for one side (which at the baserel level is currently always a Partial Seq Scan) to an ordinary path on the other side. This is subject to various restrictions at present, especially that this strategy seems unlikely to be sensible for merge joins, so only nested loops and hash joins paths are generated. This also allows an Append node to be pushed below a Gather node in the case of a partitioned table. Testing revealed that early versions of this patch made poor decisions in some cases, which turned out to be caused by the fact that the original cost model for Parallel Seq Scan wasn't very good. So this patch tries to make some modest improvements in that area. There is much more to be done in the area of generating good parallel plans in all cases, but this seems like a useful step forward. Patch by me, reviewed by Dilip Kumar and Amit Kapila.
2016-01-20 20:29:22 +01:00
ParamPathInfo *param_info);
Redesign tablesample method API, and do extensive code review. The original implementation of TABLESAMPLE modeled the tablesample method API on index access methods, which wasn't a good choice because, without specialized DDL commands, there's no way to build an extension that can implement a TSM. (Raw inserts into system catalogs are not an acceptable thing to do, because we can't undo them during DROP EXTENSION, nor will pg_upgrade behave sanely.) Instead adopt an API more like procedural language handlers or foreign data wrappers, wherein the only SQL-level support object needed is a single handler function identified by having a special return type. This lets us get rid of the supporting catalog altogether, so that no custom DDL support is needed for the feature. Adjust the API so that it can support non-constant tablesample arguments (the original coding assumed we could evaluate the argument expressions at ExecInitSampleScan time, which is undesirable even if it weren't outright unsafe), and discourage sampling methods from looking at invisible tuples. Make sure that the BERNOULLI and SYSTEM methods are genuinely repeatable within and across queries, as required by the SQL standard, and deal more honestly with methods that can't support that requirement. Make a full code-review pass over the tablesample additions, and fix assorted bugs, omissions, infelicities, and cosmetic issues (such as failure to put the added code stanzas in a consistent ordering). Improve EXPLAIN's output of tablesample plans, too. Back-patch to 9.5 so that we don't have to support the original API in production.
2015-07-25 20:39:00 +02:00
extern void cost_samplescan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
ParamPathInfo *param_info);
Rethink representation of index clauses' mapping to index columns. In commit e2c2c2e8b1df7dfdb01e7e6f6191a569ce3c3195 I made use of nested list structures to show which clauses went with which index columns, but on reflection that's a data structure that only an old-line Lisp hacker could love. Worse, it adds unnecessary complication to the many places that don't much care which clauses go with which index columns. Revert to the previous arrangement of flat lists of clauses, and instead add a parallel integer list of column numbers. The places that care about the pairing can chase both lists with forboth(), while the places that don't care just examine one list the same as before. The only real downside to this is that there are now two more lists that need to be passed to amcostestimate functions in case they care about column matching (which btcostestimate does, so not passing the info is not an option). Rather than deal with 11-argument amcostestimate functions, pass just the IndexPath and expect the functions to extract fields from it. That gets us down to 7 arguments which is better than 11, and it seems more future-proof against likely additions to the information we keep about an index path.
2011-12-25 01:03:21 +01:00
extern void cost_index(IndexPath *path, PlannerInfo *root,
Run pgindent on 9.2 source tree in preparation for first 9.3 commit-fest.
2012-06-10 21:20:04 +02:00
double loop_count);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
Revise parameterized-path mechanism to fix assorted issues. This patch adjusts the treatment of parameterized paths so that all paths with the same parameterization (same set of required outer rels) for the same relation will have the same rowcount estimate. We cache the rowcount estimates to ensure that property, and hopefully save a few cycles too. Doing this makes it practical for add_path_precheck to operate without a rowcount estimate: it need only assume that paths with different parameterizations never dominate each other, which is close enough to true anyway for coarse filtering, because normally a more-parameterized path should yield fewer rows thanks to having more join clauses to apply. In add_path, we do the full nine yards of comparing rowcount estimates along with everything else, so that we can discard parameterized paths that don't actually have an advantage. This fixes some issues I'd found with add_path rejecting parameterized paths on the grounds that they were more expensive than not-parameterized ones, even though they yielded many fewer rows and hence would be cheaper once subsequent joining was considered. To make the same-rowcounts assumption valid, we have to require that any parameterized path enforce *all* join clauses that could be obtained from the particular set of outer rels, even if not all of them are useful for indexing. This is required at both base scans and joins. It's a good thing anyway since the net impact is that join quals are checked at the lowest practical level in the join tree. Hence, discard the original rather ad-hoc mechanism for choosing parameterization joinquals, and build a better one that has a more principled rule for when clauses can be moved. The original rule was actually buggy anyway for lack of knowledge about which relations are part of an outer join's outer side; getting this right requires adding an outer_relids field to RestrictInfo.
2012-04-19 21:52:46 +02:00
ParamPathInfo *param_info,
Use parameterized paths to generate inner indexscans more flexibly. This patch fixes the planner so that it can generate nestloop-with- inner-indexscan plans even with one or more levels of joining between the indexscan and the nestloop join that is supplying the parameter. The executor was fixed to handle such cases some time ago, but the planner was not ready. This should improve our plans in many situations where join ordering restrictions formerly forced complete table scans. There is probably a fair amount of tuning work yet to be done, because of various heuristics that have been added to limit the number of parameterized paths considered. However, we are not going to find out what needs to be adjusted until the code gets some real-world use, so it's time to get it in there where it can be tested easily. Note API change for index AM amcostestimate functions. I'm not aware of any non-core index AMs, but if there are any, they will need minor adjustments.
2012-01-28 01:26:38 +01:00
Path *bitmapqual, double loop_count);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_bitmap_and_node(BitmapAndPath *path, PlannerInfo *root);
extern void cost_bitmap_or_node(BitmapOrPath *path, PlannerInfo *root);
First cut at planner support for bitmap index scans. Lots to do yet, but the code is basically working. Along the way, rewrite the entire approach to processing OR index conditions, and make it work in join cases for the first time ever. orindxpath.c is now basically obsolete, but I left it in for the time being to allow easy comparison testing against the old implementation.
2005-04-22 23:58:32 +02:00
extern void cost_bitmap_tree_node(Path *path, Cost *cost, Selectivity *selec);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_tidscan(Path *path, PlannerInfo *root,
Fix up planner infrastructure to support LATERAL properly. This patch takes care of a number of problems having to do with failure to choose valid join orders and incorrect handling of lateral references pulled up from subqueries. Notable changes: * Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to represent join ordering constraints created by lateral references. (I first considered extending the SpecialJoinInfo structure, but the semantics are different enough that a separate data structure seems better.) Extend join_is_legal() and related functions to prevent trying to form unworkable joins, and to ensure that we will consider joins that satisfy lateral references even if the joins would be clauseless. * Fill in the infrastructure needed for the last few types of relation scan paths to support parameterization. We'd have wanted this eventually anyway, but it is necessary now because a relation that gets pulled up out of a UNION ALL subquery may acquire a reltargetlist containing lateral references, meaning that its paths *have* to be parameterized whether or not we have any code that can push join quals down into the scan. * Compute data about lateral references early in query_planner(), and save in RelOptInfo nodes, to avoid repetitive calculations later. * Assorted corner-case bug fixes. There's probably still some bugs left, but this is a lot closer to being real than it was before.
2012-08-27 04:48:55 +02:00
RelOptInfo *baserel, List *tidquals, ParamPathInfo *param_info);
Make the upper part of the planner work by generating and comparing Paths. I've been saying we needed to do this for more than five years, and here it finally is. This patch removes the ever-growing tangle of spaghetti logic that grouping_planner() used to use to try to identify the best plan for post-scan/join query steps. Now, there is (nearly) independent consideration of each execution step, and entirely separate construction of Paths to represent each of the possible ways to do that step. We choose the best Path or set of Paths using the same add_path() logic that's been used inside query_planner() for years. In addition, this patch removes the old restriction that subquery_planner() could return only a single Plan. It now returns a RelOptInfo containing a set of Paths, just as query_planner() does, and the parent query level can use each of those Paths as the basis of a SubqueryScanPath at its level. This allows finding some optimizations that we missed before, wherein a subquery was capable of returning presorted data and thereby avoiding a sort in the parent level, making the overall cost cheaper even though delivering sorted output was not the cheapest plan for the subquery in isolation. (A couple of regression test outputs change in consequence of that. However, there is very little change in visible planner behavior overall, because the point of this patch is not to get immediate planning benefits but to create the infrastructure for future improvements.) There is a great deal left to do here. This patch unblocks a lot of planner work that was basically impractical in the old code structure, such as allowing FDWs to implement remote aggregation, or rewriting plan_set_operations() to allow consideration of multiple implementation orders for set operations. (The latter will likely require a full rewrite of plan_set_operations(); what I've done here is only to fix it to return Paths not Plans.) I have also left unfinished some localized refactoring in createplan.c and planner.c, because it was not necessary to get this patch to a working state. Thanks to Robert Haas, David Rowley, and Amit Kapila for review.
2016-03-07 21:58:22 +01:00
extern void cost_subqueryscan(SubqueryScanPath *path, PlannerInfo *root,
Run pgindent on 9.2 source tree in preparation for first 9.3 commit-fest.
2012-06-10 21:20:04 +02:00
RelOptInfo *baserel, ParamPathInfo *param_info);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_functionscan(Path *path, PlannerInfo *root,
Implement SQL-standard LATERAL subqueries. This patch implements the standard syntax of LATERAL attached to a sub-SELECT in FROM, and also allows LATERAL attached to a function in FROM, since set-returning function calls are expected to be one of the principal use-cases. The main change here is a rewrite of the mechanism for keeping track of which relations are visible for column references while the FROM clause is being scanned. The parser "namespace" lists are no longer lists of bare RTEs, but are lists of ParseNamespaceItem structs, which carry an RTE pointer as well as some visibility-controlling flags. Aside from supporting LATERAL correctly, this lets us get rid of the ancient hacks that required rechecking subqueries and JOIN/ON and function-in-FROM expressions for invalid references after they were initially parsed. Invalid column references are now always correctly detected on sight. In passing, remove assorted parser error checks that are now dead code by virtue of our having gotten rid of add_missing_from, as well as some comments that are obsolete for the same reason. (It was mainly add_missing_from that caused so much fudging here in the first place.) The planner support for this feature is very minimal, and will be improved in future patches. It works well enough for testing purposes, though. catversion bump forced due to new field in RangeTblEntry.
2012-08-08 01:02:54 +02:00
RelOptInfo *baserel, ParamPathInfo *param_info);
Add support for multi-row VALUES clauses as part of INSERT statements (e.g. "INSERT ... VALUES (...), (...), ...") and elsewhere as allowed by the spec. (e.g. similar to a FROM clause subselect). initdb required. Joe Conway and Tom Lane.
2006-08-02 03:59:48 +02:00
extern void cost_valuesscan(Path *path, PlannerInfo *root,
More fixes for planner's handling of LATERAL. Re-allow subquery pullup for LATERAL subqueries, except when the subquery is below an outer join and contains lateral references to relations outside that outer join. If we pull up in such a case, we risk introducing lateral cross-references into outer joins' ON quals, which is something the code is entirely unprepared to cope with right now; and I'm not sure it'll ever be worth coping with. Support lateral refs in VALUES (this seems to be the only additional path type that needs such support as a consequence of re-allowing subquery pullup). Put in a slightly hacky fix for joinpath.c's refusal to consider parameterized join paths even when there cannot be any unparameterized ones. This was causing "could not devise a query plan for the given query" failures in queries involving more than two FROM items. Put in an even more hacky fix for distribute_qual_to_rels() being unhappy with join quals that contain references to rels outside their syntactic scope; which is to say, disable that test altogether. Need to think about how to preserve some sort of debugging cross-check here, while not expending more cycles than befits a debugging cross-check.
2012-08-12 22:01:26 +02:00
RelOptInfo *baserel, ParamPathInfo *param_info);
Fix up planner infrastructure to support LATERAL properly. This patch takes care of a number of problems having to do with failure to choose valid join orders and incorrect handling of lateral references pulled up from subqueries. Notable changes: * Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to represent join ordering constraints created by lateral references. (I first considered extending the SpecialJoinInfo structure, but the semantics are different enough that a separate data structure seems better.) Extend join_is_legal() and related functions to prevent trying to form unworkable joins, and to ensure that we will consider joins that satisfy lateral references even if the joins would be clauseless. * Fill in the infrastructure needed for the last few types of relation scan paths to support parameterization. We'd have wanted this eventually anyway, but it is necessary now because a relation that gets pulled up out of a UNION ALL subquery may acquire a reltargetlist containing lateral references, meaning that its paths *have* to be parameterized whether or not we have any code that can push join quals down into the scan. * Compute data about lateral references early in query_planner(), and save in RelOptInfo nodes, to avoid repetitive calculations later. * Assorted corner-case bug fixes. There's probably still some bugs left, but this is a lot closer to being real than it was before.
2012-08-27 04:48:55 +02:00
extern void cost_ctescan(Path *path, PlannerInfo *root,
RelOptInfo *baserel, ParamPathInfo *param_info);
Make the upper part of the planner work by generating and comparing Paths. I've been saying we needed to do this for more than five years, and here it finally is. This patch removes the ever-growing tangle of spaghetti logic that grouping_planner() used to use to try to identify the best plan for post-scan/join query steps. Now, there is (nearly) independent consideration of each execution step, and entirely separate construction of Paths to represent each of the possible ways to do that step. We choose the best Path or set of Paths using the same add_path() logic that's been used inside query_planner() for years. In addition, this patch removes the old restriction that subquery_planner() could return only a single Plan. It now returns a RelOptInfo containing a set of Paths, just as query_planner() does, and the parent query level can use each of those Paths as the basis of a SubqueryScanPath at its level. This allows finding some optimizations that we missed before, wherein a subquery was capable of returning presorted data and thereby avoiding a sort in the parent level, making the overall cost cheaper even though delivering sorted output was not the cheapest plan for the subquery in isolation. (A couple of regression test outputs change in consequence of that. However, there is very little change in visible planner behavior overall, because the point of this patch is not to get immediate planning benefits but to create the infrastructure for future improvements.) There is a great deal left to do here. This patch unblocks a lot of planner work that was basically impractical in the old code structure, such as allowing FDWs to implement remote aggregation, or rewriting plan_set_operations() to allow consideration of multiple implementation orders for set operations. (The latter will likely require a full rewrite of plan_set_operations(); what I've done here is only to fix it to return Paths not Plans.) I have also left unfinished some localized refactoring in createplan.c and planner.c, because it was not necessary to get this patch to a working state. Thanks to Robert Haas, David Rowley, and Amit Kapila for review.
2016-03-07 21:58:22 +01:00
extern void cost_recursive_union(Path *runion, Path *nrterm, Path *rterm);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_sort(Path *path, PlannerInfo *root,
Teach tuplesort.c about "top N" sorting, in which only the first N tuples need be returned. We keep a heap of the current best N tuples and sift-up new tuples into it as we scan the input. For M input tuples this means only about M*log(N) comparisons instead of M*log(M), not to mention a lot less workspace when N is small --- avoiding spill-to-disk for large M is actually the most attractive thing about it. Patch includes planner and executor support for invoking this facility in ORDER BY ... LIMIT queries. Greg Stark, with some editorialization by moi.
2007-05-04 03:13:45 +02:00
List *pathkeys, Cost input_cost, double tuples, int width,
Teach CLUSTER to use seqscan-and-sort when it's faster than indexscan. ... or at least, when the planner's cost estimates say it will be faster. Leonardo Francalanci, reviewed by Itagaki Takahiro and Tom Lane
2010-10-08 02:00:28 +02:00
Cost comparison_cost, int sort_mem,
Teach tuplesort.c about "top N" sorting, in which only the first N tuples need be returned. We keep a heap of the current best N tuples and sift-up new tuples into it as we scan the input. For M input tuples this means only about M*log(N) comparisons instead of M*log(M), not to mention a lot less workspace when N is small --- avoiding spill-to-disk for large M is actually the most attractive thing about it. Patch includes planner and executor support for invoking this facility in ORDER BY ... LIMIT queries. Greg Stark, with some editorialization by moi.
2007-05-04 03:13:45 +02:00
double limit_tuples);
Support MergeAppend plans, to allow sorted output from append relations. This patch eliminates the former need to sort the output of an Append scan when an ordered scan of an inheritance tree is wanted. This should be particularly useful for fast-start cases such as queries with LIMIT. Original patch by Greg Stark, with further hacking by Hans-Jurgen Schonig, Robert Haas, and Tom Lane.
2010-10-14 22:56:39 +02:00
extern void cost_merge_append(Path *path, PlannerInfo *root,
List *pathkeys, int n_streams,
Cost input_startup_cost, Cost input_total_cost,
double tuples);
Be more realistic about plans involving Materialize nodes: take their cost into account while planning.
2002-11-30 06:21:03 +01:00
extern void cost_material(Path *path,
Rewrite the planner's handling of materialized plan types so that there is an explicit model of rescan costs being different from first-time costs. The costing of Material nodes in particular now has some visible relationship to the actual runtime behavior, where before it was essentially fantasy. This also fixes up a couple of places where different materialized plan types were treated differently for no very good reason (probably just oversights). A couple of the regression tests are affected, because the planner now chooses to put the other relation on the inside of a nestloop-with-materialize. So far as I can see both changes are sane, and the planner is now more consistently following the expectation that it should prefer to materialize the smaller of two relations. Per a recent discussion with Robert Haas.
2009-09-13 00:12:09 +02:00
Cost input_startup_cost, Cost input_total_cost,
double tuples, int width);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_agg(Path *path, PlannerInfo *root,
Improve cost estimation for aggregates and window functions. The previous coding failed to account properly for the costs of evaluating the input expressions of aggregates and window functions, as seen in a recent gripe from Claudio Freire. (I said at the time that it wasn't counting these costs at all; but on closer inspection, it was effectively charging these costs once per output tuple. That is completely wrong for aggregates, and not exactly right for window functions either.) There was also a hard-wired assumption that aggregates and window functions had procost 1.0, which is now fixed to respect the actual cataloged costs. The costing of WindowAgg is still pretty bogus, since it doesn't try to estimate the effects of spilling data to disk, but that seems like a separate issue.
2011-04-24 22:55:20 +02:00
AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
pgindent run.
2003-08-04 02:43:34 +02:00
int numGroupCols, double numGroups,
Cost input_startup_cost, Cost input_total_cost,
double input_tuples);
Support window functions a la SQL:2008. Hitoshi Harada, with some kibitzing from Heikki and Tom.
2008-12-28 19:54:01 +01:00
extern void cost_windowagg(Path *path, PlannerInfo *root,
Improve cost estimation for aggregates and window functions. The previous coding failed to account properly for the costs of evaluating the input expressions of aggregates and window functions, as seen in a recent gripe from Claudio Freire. (I said at the time that it wasn't counting these costs at all; but on closer inspection, it was effectively charging these costs once per output tuple. That is completely wrong for aggregates, and not exactly right for window functions either.) There was also a hard-wired assumption that aggregates and window functions had procost 1.0, which is now fixed to respect the actual cataloged costs. The costing of WindowAgg is still pretty bogus, since it doesn't try to estimate the effects of spilling data to disk, but that seems like a separate issue.
2011-04-24 22:55:20 +02:00
List *windowFuncs, int numPartCols, int numOrderCols,
Support window functions a la SQL:2008. Hitoshi Harada, with some kibitzing from Heikki and Tom.
2008-12-28 19:54:01 +01:00
Cost input_startup_cost, Cost input_total_cost,
double input_tuples);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void cost_group(Path *path, PlannerInfo *root,
pgindent run.
2003-08-04 02:43:34 +02:00
int numGroupCols, double numGroups,
Cost input_startup_cost, Cost input_total_cost,
double input_tuples);
Use parameterized paths to generate inner indexscans more flexibly. This patch fixes the planner so that it can generate nestloop-with- inner-indexscan plans even with one or more levels of joining between the indexscan and the nestloop join that is supplying the parameter. The executor was fixed to handle such cases some time ago, but the planner was not ready. This should improve our plans in many situations where join ordering restrictions formerly forced complete table scans. There is probably a fair amount of tuning work yet to be done, because of various heuristics that have been added to limit the number of parameterized paths considered. However, we are not going to find out what needs to be adjusted until the code gets some real-world use, so it's time to get it in there where it can be tested easily. Note API change for index AM amcostestimate functions. I'm not aware of any non-core index AMs, but if there are any, they will need minor adjustments.
2012-01-28 01:26:38 +01:00
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);
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.
2015-10-01 01:23:36 +02:00
extern void cost_gather(GatherPath *path, PlannerInfo *root,
Support parallel aggregation. Parallel workers can now partially aggregate the data and pass the transition values back to the leader, which can combine the partial results to produce the final answer. David Rowley, based on earlier work by Haribabu Kommi. Reviewed by Álvaro Herrera, Tomas Vondra, Amit Kapila, James Sewell, and me.
2016-03-21 14:20:53 +01:00
RelOptInfo *baserel, ParamPathInfo *param_info, double *rows);
Arrange to convert EXISTS subqueries that are equivalent to hashable IN subqueries into the same thing you'd have gotten from IN (except always with unknownEqFalse = true, so as to get the proper semantics for an EXISTS). I believe this fixes the last case within CVS HEAD in which an EXISTS could give worse performance than an equivalent IN subquery. The tricky part of this is that if the upper query probes the EXISTS for only a few rows, the hashing implementation can actually be worse than the default, and therefore we need to make a cost-based decision about which way to use. But at the time when the planner generates plans for subqueries, it doesn't really know how many times the subquery will be executed. The least invasive solution seems to be to generate both plans and postpone the choice until execution. Therefore, in a query that has been optimized this way, EXPLAIN will show two subplans for the EXISTS, of which only one will actually get executed. There is a lot more that could be done based on this infrastructure: in particular it's interesting to consider switching to the hash plan if we start out using the non-hashed plan but find a lot more upper rows going by than we expected. I have therefore left some minor inefficiencies in place, such as initializing both subplans even though we will currently only use one.
2008-08-22 02:16:04 +02:00
extern void cost_subplan(PlannerInfo *root, SubPlan *subplan, Plan *plan);
Turn the rangetable used by the executor into a flat list, and avoid storing useless substructure for its RangeTblEntry nodes. (I chose to keep using the same struct node type and just zero out the link fields for unneeded info, rather than making a separate ExecRangeTblEntry type --- it seemed too fragile to have two different rangetable representations.) Along the way, put subplans into a list in the toplevel PlannedStmt node, and have SubPlan nodes refer to them by list index instead of direct pointers. Vadim wanted to do that years ago, but I never understood what he was on about until now. It makes things a *whole* lot more robust, because we can stop worrying about duplicate processing of subplans during expression tree traversals. That's been a constant source of bugs, and it's finally gone. There are some consequent simplifications yet to be made, like not using a separate EState for subplans in the executor, but I'll tackle that later.
2007-02-22 23:00:26 +01:00
extern void cost_qual_eval(QualCost *cost, List *quals, PlannerInfo *root);
extern void cost_qual_eval_node(QualCost *cost, Node *qual, PlannerInfo *root);
Use parameterized paths to generate inner indexscans more flexibly. This patch fixes the planner so that it can generate nestloop-with- inner-indexscan plans even with one or more levels of joining between the indexscan and the nestloop join that is supplying the parameter. The executor was fixed to handle such cases some time ago, but the planner was not ready. This should improve our plans in many situations where join ordering restrictions formerly forced complete table scans. There is probably a fair amount of tuning work yet to be done, because of various heuristics that have been added to limit the number of parameterized paths considered. However, we are not going to find out what needs to be adjusted until the code gets some real-world use, so it's time to get it in there where it can be tested easily. Note API change for index AM amcostestimate functions. I'm not aware of any non-core index AMs, but if there are any, they will need minor adjustments.
2012-01-28 01:26:38 +01:00
extern void compute_semi_anti_join_factors(PlannerInfo *root,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
SpecialJoinInfo *sjinfo,
List *restrictlist,
SemiAntiJoinFactors *semifactors);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void set_baserel_size_estimates(PlannerInfo *root, RelOptInfo *rel);
Revise parameterized-path mechanism to fix assorted issues. This patch adjusts the treatment of parameterized paths so that all paths with the same parameterization (same set of required outer rels) for the same relation will have the same rowcount estimate. We cache the rowcount estimates to ensure that property, and hopefully save a few cycles too. Doing this makes it practical for add_path_precheck to operate without a rowcount estimate: it need only assume that paths with different parameterizations never dominate each other, which is close enough to true anyway for coarse filtering, because normally a more-parameterized path should yield fewer rows thanks to having more join clauses to apply. In add_path, we do the full nine yards of comparing rowcount estimates along with everything else, so that we can discard parameterized paths that don't actually have an advantage. This fixes some issues I'd found with add_path rejecting parameterized paths on the grounds that they were more expensive than not-parameterized ones, even though they yielded many fewer rows and hence would be cheaper once subsequent joining was considered. To make the same-rowcounts assumption valid, we have to require that any parameterized path enforce *all* join clauses that could be obtained from the particular set of outer rels, even if not all of them are useful for indexing. This is required at both base scans and joins. It's a good thing anyway since the net impact is that join quals are checked at the lowest practical level in the join tree. Hence, discard the original rather ad-hoc mechanism for choosing parameterization joinquals, and build a better one that has a more principled rule for when clauses can be moved. The original rule was actually buggy anyway for lack of knowledge about which relations are part of an outer join's outer side; getting this right requires adding an outer_relids field to RestrictInfo.
2012-04-19 21:52:46 +02:00
extern double get_parameterized_baserel_size(PlannerInfo *root,
Run pgindent on 9.2 source tree in preparation for first 9.3 commit-fest.
2012-06-10 21:20:04 +02:00
RelOptInfo *rel,
List *param_clauses);
Revise parameterized-path mechanism to fix assorted issues. This patch adjusts the treatment of parameterized paths so that all paths with the same parameterization (same set of required outer rels) for the same relation will have the same rowcount estimate. We cache the rowcount estimates to ensure that property, and hopefully save a few cycles too. Doing this makes it practical for add_path_precheck to operate without a rowcount estimate: it need only assume that paths with different parameterizations never dominate each other, which is close enough to true anyway for coarse filtering, because normally a more-parameterized path should yield fewer rows thanks to having more join clauses to apply. In add_path, we do the full nine yards of comparing rowcount estimates along with everything else, so that we can discard parameterized paths that don't actually have an advantage. This fixes some issues I'd found with add_path rejecting parameterized paths on the grounds that they were more expensive than not-parameterized ones, even though they yielded many fewer rows and hence would be cheaper once subsequent joining was considered. To make the same-rowcounts assumption valid, we have to require that any parameterized path enforce *all* join clauses that could be obtained from the particular set of outer rels, even if not all of them are useful for indexing. This is required at both base scans and joins. It's a good thing anyway since the net impact is that join quals are checked at the lowest practical level in the join tree. Hence, discard the original rather ad-hoc mechanism for choosing parameterization joinquals, and build a better one that has a more principled rule for when clauses can be moved. The original rule was actually buggy anyway for lack of knowledge about which relations are part of an outer join's outer side; getting this right requires adding an outer_relids field to RestrictInfo.
2012-04-19 21:52:46 +02:00
extern double get_parameterized_joinrel_size(PlannerInfo *root,
Run pgindent on 9.2 source tree in preparation for first 9.3 commit-fest.
2012-06-10 21:20:04 +02:00
RelOptInfo *rel,
double outer_rows,
double inner_rows,
SpecialJoinInfo *sjinfo,
List *restrict_clauses);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void set_joinrel_size_estimates(PlannerInfo *root, RelOptInfo *rel,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
RelOptInfo *outer_rel,
RelOptInfo *inner_rel,
Implement SEMI and ANTI joins in the planner and executor. (Semijoins replace the old JOIN_IN code, but antijoins are new functionality.) Teach the planner to convert appropriate EXISTS and NOT EXISTS subqueries into semi and anti joins respectively. Also, LEFT JOINs with suitable upper-level IS NULL filters are recognized as being anti joins. Unify the InClauseInfo and OuterJoinInfo infrastructure into "SpecialJoinInfo". With that change, it becomes possible to associate a SpecialJoinInfo with every join attempt, which permits some cleanup of join selectivity estimation. That needs to be taken much further than this patch does, but the next step is to change the API for oprjoin selectivity functions, which seems like material for a separate patch. So for the moment the output size estimates for semi and especially anti joins are quite bogus.
2008-08-14 20:48:00 +02:00
SpecialJoinInfo *sjinfo,
Ye-old pgindent run. Same 4-space tabs.
2000-04-12 19:17:23 +02:00
List *restrictlist);
Rearrange planner to save the whole PlannerInfo (subroot) for a subquery. Formerly, set_subquery_pathlist and other creators of plans for subqueries saved only the rangetable and rowMarks lists from the lower-level PlannerInfo. But there's no reason not to remember the whole PlannerInfo, and indeed this turns out to simplify matters in a number of places. The immediate reason for doing this was so that the subroot will still be accessible when we're trying to extract column statistics out of an already-planned subquery. But now that I've done it, it seems like a good code-beautification effort in its own right. I also chose to get rid of the transient subrtable and subrowmark fields in SubqueryScan nodes, in favor of having setrefs.c look up the subquery's RelOptInfo. That required changing all the APIs in setrefs.c to pass PlannerInfo not PlannerGlobal, which was a large but quite mechanical transformation. One side-effect not foreseen at the beginning is that this finally broke inheritance_planner's assumption that replanning the same subquery RTE N times would necessarily give interchangeable results each time. That assumption was always pretty risky, but now we really have to make a separate RTE for each instance so that there's a place to carry the separate subroots.
2011-09-03 21:35:12 +02:00
extern void set_subquery_size_estimates(PlannerInfo *root, RelOptInfo *rel);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern void set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel);
Add support for multi-row VALUES clauses as part of INSERT statements (e.g. "INSERT ... VALUES (...), (...), ...") and elsewhere as allowed by the spec. (e.g. similar to a FROM clause subselect). initdb required. Joe Conway and Tom Lane.
2006-08-02 03:59:48 +02:00
extern void set_values_size_estimates(PlannerInfo *root, RelOptInfo *rel);
Implement SQL-standard WITH clauses, including WITH RECURSIVE. There are some unimplemented aspects: recursive queries must use UNION ALL (should allow UNION too), and we don't have SEARCH or CYCLE clauses. These might or might not get done for 8.4, but even without them it's a pretty useful feature. There are also a couple of small loose ends and definitional quibbles, which I'll send a memo about to pgsql-hackers shortly. But let's land the patch now so we can get on with other development. Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane
2008-10-04 23:56:55 +02:00
extern void set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel,
Make the upper part of the planner work by generating and comparing Paths. I've been saying we needed to do this for more than five years, and here it finally is. This patch removes the ever-growing tangle of spaghetti logic that grouping_planner() used to use to try to identify the best plan for post-scan/join query steps. Now, there is (nearly) independent consideration of each execution step, and entirely separate construction of Paths to represent each of the possible ways to do that step. We choose the best Path or set of Paths using the same add_path() logic that's been used inside query_planner() for years. In addition, this patch removes the old restriction that subquery_planner() could return only a single Plan. It now returns a RelOptInfo containing a set of Paths, just as query_planner() does, and the parent query level can use each of those Paths as the basis of a SubqueryScanPath at its level. This allows finding some optimizations that we missed before, wherein a subquery was capable of returning presorted data and thereby avoiding a sort in the parent level, making the overall cost cheaper even though delivering sorted output was not the cheapest plan for the subquery in isolation. (A couple of regression test outputs change in consequence of that. However, there is very little change in visible planner behavior overall, because the point of this patch is not to get immediate planning benefits but to create the infrastructure for future improvements.) There is a great deal left to do here. This patch unblocks a lot of planner work that was basically impractical in the old code structure, such as allowing FDWs to implement remote aggregation, or rewriting plan_set_operations() to allow consideration of multiple implementation orders for set operations. (The latter will likely require a full rewrite of plan_set_operations(); what I've done here is only to fix it to return Paths not Plans.) I have also left unfinished some localized refactoring in createplan.c and planner.c, because it was not necessary to get this patch to a working state. Thanks to Robert Haas, David Rowley, and Amit Kapila for review.
2016-03-07 21:58:22 +01:00
double cte_rows);
Implement an API to let foreign-data wrappers actually be functional. This commit provides the core code and documentation needed. A contrib module test case will follow shortly. Shigeru Hanada, Jan Urbanski, Heikki Linnakangas
2011-02-20 06:17:18 +01:00
extern void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel);
Make the upper part of the planner work by generating and comparing Paths. I've been saying we needed to do this for more than five years, and here it finally is. This patch removes the ever-growing tangle of spaghetti logic that grouping_planner() used to use to try to identify the best plan for post-scan/join query steps. Now, there is (nearly) independent consideration of each execution step, and entirely separate construction of Paths to represent each of the possible ways to do that step. We choose the best Path or set of Paths using the same add_path() logic that's been used inside query_planner() for years. In addition, this patch removes the old restriction that subquery_planner() could return only a single Plan. It now returns a RelOptInfo containing a set of Paths, just as query_planner() does, and the parent query level can use each of those Paths as the basis of a SubqueryScanPath at its level. This allows finding some optimizations that we missed before, wherein a subquery was capable of returning presorted data and thereby avoiding a sort in the parent level, making the overall cost cheaper even though delivering sorted output was not the cheapest plan for the subquery in isolation. (A couple of regression test outputs change in consequence of that. However, there is very little change in visible planner behavior overall, because the point of this patch is not to get immediate planning benefits but to create the infrastructure for future improvements.) There is a great deal left to do here. This patch unblocks a lot of planner work that was basically impractical in the old code structure, such as allowing FDWs to implement remote aggregation, or rewriting plan_set_operations() to allow consideration of multiple implementation orders for set operations. (The latter will likely require a full rewrite of plan_set_operations(); what I've done here is only to fix it to return Paths not Plans.) I have also left unfinished some localized refactoring in createplan.c and planner.c, because it was not necessary to get this patch to a working state. Thanks to Robert Haas, David Rowley, and Amit Kapila for review.
2016-03-07 21:58:22 +01:00
extern PathTarget *set_pathtarget_cost_width(PlannerInfo *root, PathTarget *target);
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
/*
Another round of planner/optimizer work. This is just restructuring and code cleanup; no major improvements yet. However, EXPLAIN does produce more intuitive outputs for nested loops with indexscans now...
2000-01-09 01:26:47 +01:00
* prototypes for clausesel.c
Massive commit to run PGINDENT on all *.c and *.h files.
1997-09-07 07:04:48 +02:00
* routines to compute clause selectivities
Postgres95 1.01 Distribution - Virgin Sources
1996-07-09 08:22:35 +02:00
*/
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern Selectivity clauselist_selectivity(PlannerInfo *root,
pgindent run.
2003-08-04 02:43:34 +02:00
List *clauses,
int varRelid,
Implement SEMI and ANTI joins in the planner and executor. (Semijoins replace the old JOIN_IN code, but antijoins are new functionality.) Teach the planner to convert appropriate EXISTS and NOT EXISTS subqueries into semi and anti joins respectively. Also, LEFT JOINs with suitable upper-level IS NULL filters are recognized as being anti joins. Unify the InClauseInfo and OuterJoinInfo infrastructure into "SpecialJoinInfo". With that change, it becomes possible to associate a SpecialJoinInfo with every join attempt, which permits some cleanup of join selectivity estimation. That needs to be taken much further than this patch does, but the next step is to change the API for oprjoin selectivity functions, which seems like material for a separate patch. So for the moment the output size estimates for semi and especially anti joins are quite bogus.
2008-08-14 20:48:00 +02:00
JoinType jointype,
SpecialJoinInfo *sjinfo);
Remove planner's private fields from Query struct, and put them into a new PlannerInfo struct, which is passed around instead of the bare Query in all the planning code. This commit is essentially just a code-beautification exercise, but it does open the door to making larger changes to the planner data structures without having to muck with the widely-known Query struct.
2005-06-06 00:32:58 +02:00
extern Selectivity clause_selectivity(PlannerInfo *root,
pgindent run.
2003-08-04 02:43:34 +02:00
Node *clause,
int varRelid,
Implement SEMI and ANTI joins in the planner and executor. (Semijoins replace the old JOIN_IN code, but antijoins are new functionality.) Teach the planner to convert appropriate EXISTS and NOT EXISTS subqueries into semi and anti joins respectively. Also, LEFT JOINs with suitable upper-level IS NULL filters are recognized as being anti joins. Unify the InClauseInfo and OuterJoinInfo infrastructure into "SpecialJoinInfo". With that change, it becomes possible to associate a SpecialJoinInfo with every join attempt, which permits some cleanup of join selectivity estimation. That needs to be taken much further than this patch does, but the next step is to change the API for oprjoin selectivity functions, which seems like material for a separate patch. So for the moment the output size estimates for semi and especially anti joins are quite bogus.
2008-08-14 20:48:00 +02:00
JoinType jointype,
SpecialJoinInfo *sjinfo);
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 /* COST_H */