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path: root/src/backend/commands/explain.c
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2013-03-03Add a materialized view relations.Kevin Grittner
A materialized view has a rule just like a view and a heap and other physical properties like a table. The rule is only used to populate the table, references in queries refer to the materialized data. This is a minimal implementation, but should still be useful in many cases. Currently data is only populated "on demand" by the CREATE MATERIALIZED VIEW and REFRESH MATERIALIZED VIEW statements. It is expected that future releases will add incremental updates with various timings, and that a more refined concept of defining what is "fresh" data will be developed. At some point it may even be possible to have queries use a materialized in place of references to underlying tables, but that requires the other above-mentioned features to be working first. Much of the documentation work by Robert Haas. Review by Noah Misch, Thom Brown, Robert Haas, Marko Tiikkaja Security review by KaiGai Kohei, with a decision on how best to implement sepgsql still pending.
2013-01-01Update copyrights for 2013Bruce Momjian
Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.
2012-12-31Fix ruleutils to cope with conflicts from adding/dropping/renaming columns.Tom Lane
In commit 11e131854f8231a21613f834c40fe9d046926387, we improved the rule/view dumping code so that it would produce valid query representations even if some of the tables involved in a query had been renamed since the query was parsed. This patch extends that idea to fix problems that occur when individual columns are renamed, or added or dropped. As before, the core of the fix is to assign unique new aliases when a name conflict has been created. This is complicated by the JOIN USING feature, which requires the same column alias to be used in both input relations, but we can handle that with a sufficiently complex approach to assigning aliases. A fortiori, this patch takes care of situations where the query didn't have unique column names to begin with, such as in a recent complaint from Bryan Nuse. (Because of expansion of "SELECT *", re-parsing a dumped query can require column name uniqueness even though the original text did not.)
2012-09-21Improve ruleutils.c's heuristics for dealing with rangetable aliases.Tom Lane
The previous scheme had bugs in some corner cases involving tables that had been renamed since a view was made. This could result in dumped views that failed to reload or reloaded incorrectly, as seen in bug #7553 from Lloyd Albin, as well as in some pgsql-hackers discussion back in January. Also, its behavior for printing EXPLAIN plans was sometimes confusing because of willingness to use the same alias for multiple RTEs (it was Ashutosh Bapat's complaint about that aspect that started the January thread). To fix, ensure that each RTE in the query has a unique unqualified alias, by modifying the alias if necessary (we add "_" and digits as needed to create a non-conflicting name). Then we can just print its variables with that alias, avoiding the confusing and bug-prone scheme of sometimes schema-qualifying variable names. In EXPLAIN, it proves to be expedient to take the further step of only assigning such aliases to RTEs that are actually referenced in the query, since the planner has a habit of generating extra RTEs with the same alias in situations such as inheritance-tree expansion. Although this fixes a bug of very long standing, I'm hesitant to back-patch such a noticeable behavioral change. My experiments while creating a regression test convinced me that actually incorrect output (as opposed to confusing output) occurs only in very narrow cases, which is backed up by the lack of previous complaints from the field. So we may be better off living with it in released branches; and in any case it'd be smart to let this ripen awhile in HEAD before we consider back-patching it.
2012-06-10Run pgindent on 9.2 source tree in preparation for first 9.3Bruce Momjian
commit-fest.
2012-04-29Rename I/O timing statistics columns to blk_read_time and blk_write_time.Tom Lane
This seems more consistent with the pre-existing choices for names of other statistics columns. Rename assorted internal identifiers to match.
2012-03-27New GUC, track_iotiming, to track I/O timings.Robert Haas
Currently, the only way to see the numbers this gathers is via EXPLAIN (ANALYZE, BUFFERS), but the plan is to add visibility through the stats collector and pg_stat_statements in subsequent patches. Ants Aasma, reviewed by Greg Smith, with some further changes by me.
2012-03-19Restructure SELECT INTO's parsetree representation into CreateTableAsStmt.Tom Lane
Making this operation look like a utility statement seems generally a good idea, and particularly so in light of the desire to provide command triggers for utility statements. The original choice of representing it as SELECT with an IntoClause appendage had metastasized into rather a lot of places, unfortunately, so that this patch is a great deal more complicated than one might at first expect. In particular, keeping EXPLAIN working for SELECT INTO and CREATE TABLE AS subcommands required restructuring some EXPLAIN-related APIs. Add-on code that calls ExplainOnePlan or ExplainOneUtility, or uses ExplainOneQuery_hook, will need adjustment. Also, the cases PREPARE ... SELECT INTO and CREATE RULE ... SELECT INTO, which formerly were accepted though undocumented, are no longer accepted. The PREPARE case can be replaced with use of CREATE TABLE AS EXECUTE. The CREATE RULE case doesn't seem to have much real-world use (since the rule would work only once before failing with "table already exists"), so we'll not bother with that one. Both SELECT INTO and CREATE TABLE AS still return a command tag of "SELECT nnnn". There was some discussion of returning "CREATE TABLE nnnn", but for the moment backwards compatibility wins the day. Andres Freund and Tom Lane
2012-02-22Make EXPLAIN (BUFFERS) track blocks dirtied, as well as those written.Robert Haas
Also expose the new counters through pg_stat_statements. Patch by me. Review by Fujii Masao and Greg Smith.
2012-02-07Add TIMING option to EXPLAIN, to allow eliminating of timing overhead.Robert Haas
Sometimes it may be useful to get actual row counts out of EXPLAIN (ANALYZE) without paying the cost of timing every node entry/exit. With this patch, you can say EXPLAIN (ANALYZE, TIMING OFF) to get that. Tomas Vondra, reviewed by Eric Theise, with minor doc changes by me.
2012-02-03Add array_to_json and row_to_json functions.Andrew Dunstan
Also move the escape_json function from explain.c to json.c where it seems to belong. Andrew Dunstan, Reviewd by Abhijit Menon-Sen.
2012-01-31Built-in JSON data type.Robert Haas
Like the XML data type, we simply store JSON data as text, after checking that it is valid. More complex operations such as canonicalization and comparison may come later, but this is enough for not. There are a few open issues here, such as whether we should attempt to detect UTF-8 surrogate pairs represented as \uXXXX\uYYYY, but this gets the basic framework in place.
2012-01-25Instrument index-only scans to count heap fetches performed.Robert Haas
Patch by me; review by Tom Lane, Jeff Davis, and Peter Geoghegan.
2012-01-01Update copyright notices for year 2012.Bruce Momjian
2011-10-11Rearrange the implementation of index-only scans.Tom Lane
This commit changes index-only scans so that data is read directly from the index tuple without first generating a faux heap tuple. The only immediate benefit is that indexes on system columns (such as OID) can be used in index-only scans, but this is necessary infrastructure if we are ever to support index-only scans on expression indexes. The executor is now ready for that, though the planner still needs substantial work to recognize the possibility. To do this, Vars in index-only plan nodes have to refer to index columns not heap columns. I introduced a new special varno, INDEX_VAR, to mark such Vars to avoid confusion. (In passing, this commit renames the two existing special varnos to OUTER_VAR and INNER_VAR.) This allows ruleutils.c to handle them with logic similar to what we use for subplan reference Vars. Since index-only scans are now fundamentally different from regular indexscans so far as their expression subtrees are concerned, I also chose to change them to have their own plan node type (and hence, their own executor source file).
2011-10-07Support index-only scans using the visibility map to avoid heap fetches.Tom Lane
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.
2011-09-22Make EXPLAIN ANALYZE report the numbers of rows rejected by filter steps.Tom Lane
This provides information about the numbers of tuples that were visited but not returned by table scans, as well as the numbers of join tuples that were considered and discarded within a join plan node. There is still some discussion going on about the best way to report counts for outer-join situations, but I think most of what's in the patch would not change if we revise that, so I'm going to go ahead and commit it as-is. Documentation changes to follow (they weren't in the submitted patch either). Marko Tiikkaja, reviewed by Marc Cousin, somewhat revised by Tom
2011-09-01Remove unnecessary #include references, per pgrminclude script.Bruce Momjian
2011-07-04Move Trigger and TriggerDesc structs out of rel.h into a new reltrigger.hAlvaro Herrera
This lets us stop including rel.h into execnodes.h, which is a widely used header.
2011-04-11Clean up most -Wunused-but-set-variable warnings from gcc 4.6Peter Eisentraut
This warning is new in gcc 4.6 and part of -Wall. This patch cleans up most of the noise, but there are some still warnings that are trickier to remove.
2011-04-10pgindent run before PG 9.1 beta 1.Bruce Momjian
2011-03-01Include the target table in EXPLAIN output for ModifyTable nodes.Tom Lane
Per discussion, this seems important for plans involving writable CTEs, since there can now be more than one ModifyTable node in the plan. To retain the same formatting as for target tables of scan nodes, we show only one target table, which will be the parent table in case of an UPDATE or DELETE on an inheritance tree. Individual child tables can be determined by inspecting the child plan trees if needed.
2011-02-28Rearrange snapshot handling to make rule expansion more consistent.Tom Lane
With this patch, portals, SQL functions, and SPI all agree that there should be only a CommandCounterIncrement between the queries that are generated from a single SQL command by rule expansion. Fetching a whole new snapshot now happens only between original queries. This is equivalent to the existing behavior of EXPLAIN ANALYZE, and it was judged to be the best choice since it eliminates one source of concurrency hazards for rules. The patch should also make things marginally faster by reducing the number of snapshot push/pop operations. The patch removes pg_parse_and_rewrite(), which is no longer used anywhere. There was considerable discussion about more aggressive refactoring of the query-processing functions exported by postgres.c, but for the moment nothing more has been done there. I also took the opportunity to refactor snapmgr.c's API slightly: the former PushUpdatedSnapshot() has been split into two functions. Marko Tiikkaja, reviewed by Steve Singer and Tom Lane
2011-02-27Refactor the executor's API to support data-modifying CTEs better.Tom Lane
The originally committed patch for modifying CTEs didn't interact well with EXPLAIN, as noted by myself, and also had corner-case problems with triggers, as noted by Dean Rasheed. Those problems show it is really not practical for ExecutorEnd to call any user-defined code; so split the cleanup duties out into a new function ExecutorFinish, which must be called between the last ExecutorRun call and ExecutorEnd. Some Asserts have been added to these functions to help verify correct usage. It is no longer necessary for callers of the executor to call AfterTriggerBeginQuery/AfterTriggerEndQuery for themselves, as this is now done by ExecutorStart/ExecutorFinish respectively. If you really need to suppress that and do it for yourself, pass EXEC_FLAG_SKIP_TRIGGERS to ExecutorStart. Also, refactor portal commit processing to allow for the possibility that PortalDrop will invoke user-defined code. I think this is not actually necessary just yet, since the portal-execution-strategy logic forces any non-pure-SELECT query to be run to completion before we will consider committing. But it seems like good future-proofing.
2011-02-20Implement an API to let foreign-data wrappers actually be functional.Tom Lane
This commit provides the core code and documentation needed. A contrib module test case will follow shortly. Shigeru Hanada, Jan Urbanski, Heikki Linnakangas
2011-01-01Stamp copyrights for year 2011.Bruce Momjian
2010-12-06Put only single space after "Sort Method:", for consistencyPeter Eisentraut
2010-12-02Create core infrastructure for KNNGIST.Tom Lane
This is a heavily revised version of builtin_knngist_core-0.9. The ordering operators are no longer mixed in with actual quals, which would have confused not only humans but significant parts of the planner. Instead, ordering operators are carried separately throughout planning and execution. Since the API for ambeginscan and amrescan functions had to be changed anyway, this commit takes the opportunity to rationalize that a bit. RelationGetIndexScan no longer forces a premature index_rescan call; instead, callers of index_beginscan must call index_rescan too. Aside from making the AM-side initialization logic a bit less peculiar, this has the advantage that we do not make a useless extra am_rescan call when there are runtime key values. AMs formerly could not assume that the key values passed to amrescan were actually valid; now they can. Teodor Sigaev and Tom Lane
2010-11-23Remove useless whitespace at end of linesPeter Eisentraut
2010-10-14Support MergeAppend plans, to allow sorted output from append relations.Tom Lane
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.
2010-09-20Remove cvs keywords from all files.Magnus Hagander
2010-08-24Make EXPLAIN show the function call expression of a FunctionScan plan node,Tom Lane
but only in VERBOSE mode. Per discussion.
2010-07-13Teach EXPLAIN to print PARAM_EXEC Params as the referenced expressions,Tom Lane
rather than just $N. This brings the display of nestloop-inner-indexscan plans back to where it's been, and incidentally improves the display of SubPlan parameters as well. In passing, simplify the EXPLAIN code by having it deal primarily in the PlanState tree rather than separately searching Plan and PlanState trees. This is noticeably cleaner for subplans, and about a wash elsewhere. One small difference from previous behavior is that EXPLAIN will no longer qualify local variable references in inner-indexscan plan nodes, since it no longer sees such nodes as possibly referencing multiple tables. Vars referenced through PARAM_EXEC Params are still forcibly qualified, though, so I don't think the display is any more confusing than before. Adjust a couple of examples in the documentation to match this behavior.
2010-06-10Quote all string values in EXPLAIN (FORMAT YAML) output.Robert Haas
While my previous attempt seems to always produce valid YAML, it doesn't always produce YAML that means what it appears to mean, because of tokens like "0xa" and "true", which without quotes will be interpreted as integer or Boolean literals. So, instead, just quote everything that's not known to be a number, as we do for JSON. Dean Rasheed, with some changes to the comments by me.
2010-06-09Attempt to fix EXPLAIN (FORMAT YAML) quoting to behave sanely.Robert Haas
The previous code failed to quote in many cases where quoting was necessary - YAML has loads of special characters, including -:[]{},"'|*& - so quote much more aggressively, and only refrain from quoting things where it seems fairly clear that it isn't necessary. Per report from Dean Rasheed.
2010-02-26pgindent run for 9.0Bruce Momjian
2010-02-16Add query text to auto_explain output.Andrew Dunstan
Still to be done: fix docs and fix regression failures under auto_explain.
2010-02-16revert to showing buffer counts in explain (buffers)Greg Stark
2010-02-15Display explain buffers measurements in memory units rather than blocks. ↵Greg Stark
Also show "Total Buffer Usage" to hint that these are totals not averages per loop
2010-02-01Augment EXPLAIN output with more details on Hash nodes.Robert Haas
We show the number of buckets, the number of batches (and also the original number if it has changed), and the peak space used by the hash table. Minor executor changes to track peak space used.
2010-01-15Do parse analysis of an EXPLAIN's contained statement during the normalTom Lane
parse analysis phase, rather than at execution time. This makes parameter handling work the same as it does in ordinary plannable queries, and in particular fixes the incompatibility that Pavel pointed out with plpgsql's new handling of variable references. plancache.c gets a little bit grottier, but the alternatives seem worse.
2010-01-02Update copyright for the year 2010.Bruce Momjian
2009-12-16Several fixes for EXPLAIN (FORMAT YAML), plus one for EXPLAIN (FORMAT JSON).Robert Haas
ExplainSeparatePlans() was busted for both JSON and YAML output - the present code is a holdover from the original version of my machine-readable explain patch, which didn't have the grouping_stack machinery. Also, fix an odd distribution of labor between ExplainBeginGroup() and ExplainYAMLLineStarting() when marking lists with "- ", with each providing one character. This broke the output format for multi-query statements. Also, fix ExplainDummyGroup() for the YAML output format. Along the way, make the YAML format use escape_yaml() in situations where the JSON format uses escape_json(). Right now, it doesn't matter because all the values are known not to need escaping, but it seems safer this way. Finally, I added some comments to better explain what the YAML output format is doing. Greg Sabino Mullane reported the issues with multi-query statements. Analysis and remaining cleanups by me.
2009-12-15Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.Robert Haas
This patch also removes buffer-usage statistics from the track_counts output, since this (or the global server statistics) is deemed to be a better interface to this information. Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.
2009-12-12Export ExplainBeginOutput() and ExplainEndOutput() for auto_explain.Robert Haas
Without these functions, anyone outside of explain.c can't actually use ExplainPrintPlan, because the ExplainState won't be initialized properly. The user-visible result of this was a crash when using auto_explain with the JSON output format. Report by Euler Taveira de Oliveira. Analysis by Tom Lane. Patch by me.
2009-12-11Add YAML to list of EXPLAIN formats. Greg Sabino Mullane, reviewed by ↵Andrew Dunstan
Takahiro Itagaki.
2009-11-04Add support for invoking parser callback hooks via SPI and in cached plans.Tom Lane
As proof of concept, modify plpgsql to use the hooks. plpgsql is still inserting $n symbols textually, but the "back end" of the parsing process now goes through the ParamRef hook instead of using a fixed parameter-type array, and then execution only fetches actually-referenced parameters, using a hook added to ParamListInfo. Although there's a lot left to be done in plpgsql, this already cures the "if (TG_OP = 'INSERT' and NEW.foo ...)" problem, as illustrated by the changed regression test.
2009-10-12Move the handling of SELECT FOR UPDATE locking and rechecking out ofTom Lane
execMain.c and into a new plan node type LockRows. Like the recent change to put table updating into a ModifyTable plan node, this increases planning flexibility by allowing the operations to occur below the top level of the plan tree. It's necessary in any case to restore the previous behavior of having FOR UPDATE locking occur before ModifyTable does. This partially refactors EvalPlanQual to allow multiple rows-under-test to be inserted into the EPQ machinery before starting an EPQ test query. That isn't sufficient to fix EPQ's general bogosity in the face of plans that return multiple rows per test row, though. Since this patch is mostly about getting some plan node infrastructure in place and not about fixing ten-year-old bugs, I will leave EPQ improvements for another day. Another behavioral change that we could now think about is doing FOR UPDATE before LIMIT, but that too seems like it should be treated as a followon patch.
2009-10-10Split the processing of INSERT/UPDATE/DELETE operations out of execMain.c.Tom Lane
They are now handled by a new plan node type called ModifyTable, which is placed at the top of the plan tree. In itself this change doesn't do much, except perhaps make the handling of RETURNING lists and inherited UPDATEs a tad less klugy. But it is necessary preparation for the intended extension of allowing RETURNING queries inside WITH. Marko Tiikkaja
2009-08-22Include resjunk columns in EXPLAIN VERBOSE output lists. Per discussion.Tom Lane