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* Change the format of the VM fork to add a second bit per page.Robert Haas2016-03-01
| | | | | | | | | | | | | | | | | | | | | | | The new bit indicates whether every tuple on the page is already frozen. It is cleared only when the all-visible bit is cleared, and it can be set only when we vacuum a page and find that every tuple on that page is both visible to every transaction and in no need of any future vacuuming. A future commit will use this new bit to optimize away full-table scans that would otherwise be triggered by XID wraparound considerations. A page which is merely all-visible must still be scanned in that case, but a page which is all-frozen need not be. This commit does not attempt that optimization, although that optimization is the goal here. It seems better to get the basic infrastructure in place first. Per discussion, it's very desirable for pg_upgrade to automatically migrate existing VM forks from the old format to the new format. That, too, will be handled in a follow-on patch. Masahiko Sawada, reviewed by Kyotaro Horiguchi, Fujii Masao, Amit Kapila, Simon Riggs, Andres Freund, and others, and substantially revised by me.
* On second thought, disable parallelism for prepared statements.Robert Haas2016-02-26
| | | | | | | CREATE TABLE .. AS EXECUTE can turn an apparently read-only query into a write operation, which parallel query can't handle. It's a bit of a shame that requires us to avoid parallel query for queries prepared via PREPARE in all cases, but for right now it does.
* Enable parallelism for prepared statements and extended query protocol.Robert Haas2016-02-25
| | | | | | | | | | | | | | | | | | Parallel query can't handle running a query only partially rather than to completion. However, there seems to be no way to run a statement prepared via SQL PREPARE other than to completion, so we can enable it there without a problem. The situation is more complicated for the extend query protocol. libpq seems to provide no way to send an Execute message with a non-zero rowcount, but some other client might. If that happens, and a parallel plan was chosen, we'll execute the parallel plan without using any workers, which may be somewhat inefficient but should still work. Hopefully this won't be a problem; users can always set max_parallel_degree=0 to avoid choosing parallel plans in the first place. Amit Kapila, reviewed by me.
* Make concurrent refresh check early that there is a unique index on matview.Fujii Masao2016-02-16
| | | | | | | | | | | | | | | | | | | In REFRESH MATERIALIZED VIEW command, CONCURRENTLY option is only allowed if there is at least one unique index with no WHERE clause on one or more columns of the matview. Previously, concurrent refresh checked the existence of a unique index on the matview after filling the data to new snapshot, i.e., after calling refresh_matview_datafill(). So, when there was no unique index, we could need to wait a long time before we detected that and got the error. It was a waste of time. To eliminate such wasting time, this commit changes concurrent refresh so that it checks the existence of a unique index at the beginning of the refresh operation, i.e., before starting any time-consuming jobs. If CONCURRENTLY option is not allowed due to lack of a unique index, concurrent refresh can immediately detect it and emit an error. Author: Masahiko Sawada Reviewed-by: Michael Paquier, Fujii Masao
* Move pg_constraint.h function declarations to new file pg_constraint_fn.h.Tom Lane2016-02-11
| | | | | | | | | | | A pending patch requires exporting a function returning Bitmapset from catalog/pg_constraint.c. As things stand, that would mean including nodes/bitmapset.h in pg_constraint.h, which might be hazardous for the client-side includability of that header. It's not entirely clear whether any client-side code needs to include pg_constraint.h, but it seems prudent to assume that there is some such code somewhere. Therefore, split off the function definitions into a new file pg_constraint_fn.h, similarly to what we've done for some other catalog header files.
* Introduce a new GUC force_parallel_mode for testing purposes.Robert Haas2016-02-07
| | | | | | | | | | | | | | | When force_parallel_mode = true, we enable the parallel mode restrictions for all queries for which this is believed to be safe. For the subset of those queries believed to be safe to run entirely within a worker, we spin up a worker and run the query there instead of running it in the original process. When force_parallel_mode = regress, make additional changes to allow the regression tests to run cleanly even though parallel workers have been injected under the hood. Taken together, this facilitates both better user testing and better regression testing of the parallelism code. Robert Haas, with help from Amit Kapila and Rushabh Lathia.
* Make all built-in lwlock tranche IDs fixed.Robert Haas2016-02-02
| | | | | | | This makes the values more stable, which seems like a good thing for anybody who needs to look at at them. Alexander Korotkov and Amit Kapila
* Support multi-stage aggregation.Robert Haas2016-01-20
| | | | | | | | | | | | | | | | | | | Aggregate nodes now have two new modes: a "partial" mode where they output the unfinalized transition state, and a "finalize" mode where they accept unfinalized transition states rather than individual values as input. These new modes are not used anywhere yet, but they will be necessary for parallel aggregation. The infrastructure also figures to be useful for cases where we want to aggregate local data and remote data via the FDW interface, and want to bring back partial aggregates from the remote side that can then be combined with locally generated partial aggregates to produce the final value. It may also be useful even when neither FDWs nor parallelism are in play, as explained in the comments in nodeAgg.c. David Rowley and Simon Riggs, reviewed by KaiGai Kohei, Heikki Linnakangas, Haribabu Kommi, and me.
* Restructure index access method API to hide most of it at the C level.Tom Lane2016-01-17
| | | | | | | | | | | | | | | | | | | | | | | | This patch reduces pg_am to just two columns, a name and a handler function. All the data formerly obtained from pg_am is now provided in a C struct returned by the handler function. This is similar to the designs we've adopted for FDWs and tablesample methods. There are multiple advantages. For one, the index AM's support functions are now simple C functions, making them faster to call and much less error-prone, since the C compiler can now check function signatures. For another, this will make it far more practical to define index access methods in installable extensions. A disadvantage is that SQL-level code can no longer see attributes of index AMs; in particular, some of the crosschecks in the opr_sanity regression test are no longer possible from SQL. We've addressed that by adding a facility for the index AM to perform such checks instead. (Much more could be done in that line, but for now we're content if the amvalidate functions more or less replace what opr_sanity used to do.) We might also want to expose some sort of reporting functionality, but this patch doesn't do that. Alexander Korotkov, reviewed by Petr Jelínek, and rather heavily editorialized on by me.
* Fix bogus lock release in RemovePolicyById and RemoveRoleFromObjectPolicy.Tom Lane2016-01-03
| | | | | | | | | | | | | | Can't release the AccessExclusiveLock on the target table until commit. Otherwise there is a race condition whereby other backends might service our cache invalidation signals before they can actually see the updated catalog rows. Just to add insult to injury, RemovePolicyById was closing the rel (with incorrect lock drop) and then passing the now-dangling rel pointer to CacheInvalidateRelcache. Probably the reason this doesn't fall over on CLOBBER_CACHE buildfarm members is that some outer level of the DROP logic is still holding the rel open ... but it'd have bit us on the arse eventually, no doubt.
* Update copyright for 2016Bruce Momjian2016-01-02
| | | | Backpatch certain files through 9.1
* Fix ALTER OPERATOR to update dependencies properly.Tom Lane2015-12-31
| | | | | | | | | | | | | | Fix an oversight in commit 321eed5f0f7563a0: replacing an operator's selectivity functions needs to result in a corresponding update in pg_depend. We have a function that can handle that, but it was not called by AlterOperator(). To fix this without enlarging pg_operator.h's #include list beyond what clients can safely include, split off the function definitions into a new file pg_operator_fn.h, similarly to what we've done for some other catalog header files. It's not entirely clear whether any client-side code needs to include pg_operator.h, but it seems prudent to assume that there is some such code somewhere.
* Dept of second thoughts: the !scan_all exit mustn't increase scanned_pages.Tom Lane2015-12-30
| | | | | | In the extreme edge case where contended pages are the only ones that escape being scanned, the previous commit would have allowed us to think that relfrozenxid could be advanced, which is exactly wrong.
* Avoid useless truncation attempts during VACUUM.Tom Lane2015-12-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | VACUUM can skip heap pages altogether when there's a run of consecutive pages that are all-visible according to the visibility map. This causes it to not update its nonempty_pages count, just as if those pages were empty, which means that at the end we will think they are candidates for deletion. Thus, we may take the table's AccessExclusive lock only to find that no pages are really truncatable. This usually causes no real problems on a master server, thanks to the lock being acquired only conditionally; but on hot-standby servers, the same lock must be acquired unconditionally which can result in unnecessary query cancellations. To improve matters, force examination of the table's last page whenever we reach there with a nonempty_pages count that would allow a truncation attempt. If it's not empty, we'll advance nonempty_pages and thereby prevent the truncation attempt. If we are unable to acquire cleanup lock on that page, there's no need to force it, unless we're doing an anti-wraparound vacuum. We can just check for tuples with a shared buffer lock and then give up. (When we are doing an anti-wraparound vacuum, and decide it's okay to skip the page because it contains no freezable tuples, this patch still improves matters because nonempty_pages is properly updated, which it was not before.) Since only the last page is special-cased in this way, we might attempt a truncation that will release many fewer pages than the normal heuristic would suggest; at worst, only one page would be truncated. But that seems all right, because the situation won't repeat during the next vacuum. The real problem with the old logic is that the useless truncation attempt happens every time we vacuum, so long as the state of the last few dozen pages doesn't change. This is a longstanding deficiency, but since the consequences aren't very severe in most scenarios, I'm not going to risk a back-patch. Jeff Janes and Tom Lane
* Rename (new|old)estCommitTs to (new|old)estCommitTsXidJoe Conway2015-12-28
| | | | | | | | | | | | | The variables newestCommitTs and oldestCommitTs sound as if they are timestamps, but in fact they are the transaction Ids that correspond to the newest and oldest timestamps rather than the actual timestamps. Rename these variables to reflect that they are actually xids: to wit newestCommitTsXid and oldestCommitTsXid respectively. Also modify related code in a similar fashion, particularly the user facing output emitted by pg_controldata and pg_resetxlog. Complaint and patch by me, review by Tom Lane and Alvaro Herrera. Backpatch to 9.5 where these variables were first introduced.
* Include typmod when complaining about inherited column type mismatches.Tom Lane2015-12-26
| | | | | | | | | | | | | | | | MergeAttributes() rejects cases where columns to be merged have the same type but different typmod, which is correct; but the error message it printed didn't show either typmod, which is unhelpful. Changing this requires using format_type_with_typemod() in place of TypeNameToString(), which will have some minor side effects on the way some type names are printed, but on balance this is an improvement: the old code sometimes printed one type according to one set of rules and the other type according to the other set, which could be confusing in its own way. Oddly, there were no regression test cases covering any of this behavior, so add some. Complaint and fix by Amit Langote
* Rework internals of changing a type's ownershipAlvaro Herrera2015-12-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is necessary so that REASSIGN OWNED does the right thing with composite types, to wit, that it also alters ownership of the type's pg_class entry -- previously, the pg_class entry remained owned by the original user, which caused later other failures such as the new owner's inability to use ALTER TYPE to rename an attribute of the affected composite. Also, if the original owner is later dropped, the pg_class entry becomes owned by a non-existant user which is bogus. To fix, create a new routine AlterTypeOwner_oid which knows whether to pass the request to ATExecChangeOwner or deal with it directly, and use that in shdepReassignOwner rather than calling AlterTypeOwnerInternal directly. AlterTypeOwnerInternal is now simpler in that it only modifies the pg_type entry and recurses to handle a possible array type; higher-level tasks are handled by either AlterTypeOwner directly or AlterTypeOwner_oid. I took the opportunity to add a few more objects to the test rig for REASSIGN OWNED, so that more cases are exercised. Additional ones could be added for superuser-only-ownable objects (such as FDWs and event triggers) but I didn't want to push my luck by adding a new superuser to the tests on a backpatchable bug fix. Per bug #13666 reported by Chris Pacejo. Backpatch to 9.5. (I would back-patch this all the way back, except that it doesn't apply cleanly in 9.4 and earlier because 59367fdf9 wasn't backpatched. If we decide that we need this in earlier branches too, we should backpatch both.)
* Fix ALTER TABLE ... SET TABLESPACE for unlogged relations.Andres Freund2015-12-12
| | | | | | | | | | | | | | | | | | | | | | | | | | Changing the tablespace of an unlogged relation did not WAL log the creation and content of the init fork. Thus, after a standby is promoted, unlogged relation cannot be accessed anymore, with errors like: ERROR: 58P01: could not open file "pg_tblspc/...": No such file or directory Additionally the init fork was not synced to disk, independent of the configured wal_level, a relatively small durability risk. Investigation of that problem also brought to light that, even for permanent relations, the creation of !main forks was not WAL logged, i.e. no XLOG_SMGR_CREATE record were emitted. That mostly turns out not to be a problem, because these files were created when the actual relation data is copied; nonexistent files are not treated as an error condition during replay. But that doesn't work for empty files, and generally feels a bit haphazard. Luckily, outside init and main forks, empty forks don't occur often or are not a problem. Add the required WAL logging and syncing to disk. Reported-By: Michael Paquier Author: Michael Paquier and Andres Freund Discussion: 20151210163230.GA11331@alap3.anarazel.de Backpatch: 9.1, where unlogged relations were introduced
* Handle policies during DROP OWNED BYStephen Frost2015-12-11
| | | | | | | | | | DROP OWNED BY handled GRANT-based ACLs but was not removing roles from policies. Fix that by having DROP OWNED BY remove the role specified from the list of roles the policy (or policies) apply to, or the entire policy (or policies) if it only applied to the role specified. As with ACLs, the DROP OWNED BY caller must have permission to modify the policy or a WARNING is thrown and no change is made to the policy.
* Handle dependencies properly in ALTER POLICYStephen Frost2015-12-11
| | | | | | | | | | | | | | ALTER POLICY hadn't fully considered partial policy alternation (eg: change just the roles on the policy, or just change one of the expressions) when rebuilding the dependencies. Instead, it would happily remove all dependencies which existed for the policy and then only recreate the dependencies for the objects referred to in the specific ALTER POLICY command. Correct that by extracting and building the dependencies for all objects referenced by the policy, regardless of if they were provided as part of the ALTER POLICY command or were already in place as part of the pre-existing policy.
* Improve some messagesPeter Eisentraut2015-12-10
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* Allow EXPLAIN (ANALYZE, VERBOSE) to display per-worker statistics.Robert Haas2015-12-09
| | | | | | | | | | | The original parallel sequential scan commit included only very limited changes to the EXPLAIN output. Aggregated totals from all workers were displayed, but there was no way to see what each individual worker did or to distinguish the effort made by the workers from the effort made by the leader. Per a gripe by Thom Brown (and maybe others). Patch by me, reviewed by Amit Kapila.
* COPY (INSERT/UPDATE/DELETE .. RETURNING ..)Teodor Sigaev2015-11-27
| | | | | | | Attached is a patch for being able to do COPY (query) without a CTE. Author: Marko Tiikkaja Review: Michael Paquier
* Fix handling of inherited check constraints in ALTER COLUMN TYPE (again).Tom Lane2015-11-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The previous way of reconstructing check constraints was to do a separate "ALTER TABLE ONLY tab ADD CONSTRAINT" for each table in an inheritance hierarchy. However, that way has no hope of reconstructing the check constraints' own inheritance properties correctly, as pointed out in bug #13779 from Jan Dirk Zijlstra. What we should do instead is to do a regular "ALTER TABLE", allowing recursion, at the topmost table that has a particular constraint, and then suppress the work queue entries for inherited instances of the constraint. Annoyingly, we'd tried to fix this behavior before, in commit 5ed6546cf, but we failed to notice that it wasn't reconstructing the pg_constraint field values correctly. As long as I'm touching pg_get_constraintdef_worker anyway, tweak it to always schema-qualify the target table name; this seems like useful backup to the protections installed by commit 5f173040. In HEAD/9.5, get rid of get_constraint_relation_oids, which is now unused. (I could alternatively have modified it to also return conislocal, but that seemed like a pretty single-purpose API, so let's not pretend it has some other use.) It's unused in the back branches as well, but I left it in place just in case some third-party code has decided to use it. In HEAD/9.5, also rename pg_get_constraintdef_string to pg_get_constraintdef_command, as the previous name did nothing to explain what that entry point did differently from others (and its comment was equally useless). Again, that change doesn't seem like material for back-patching. I did a bit of re-pgindenting in tablecmds.c in HEAD/9.5, as well. Otherwise, back-patch to all supported branches.
* Make ALTER .. SET SCHEMA do nothing, instead of throwing an ERROR.Robert Haas2015-11-19
| | | | | | | | | This was already true for CREATE EXTENSION, but historically has not been true for other object types. Therefore, this is a backward incompatibility. Per discussion on pgsql-hackers, everyone seems to agree that the new behavior is better. Marti Raudsepp, reviewed by Haribabu Kommi and myself
* Message style fixPeter Eisentraut2015-11-17
| | | | from Euler Taveira
* Message improvementsPeter Eisentraut2015-11-16
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* Move each SLRU's lwlocks to a separate tranche.Robert Haas2015-11-12
| | | | | | | | | | This makes it significantly easier to identify these lwlocks in LWLOCK_STATS or Trace_lwlocks output. It's also arguably better from a modularity standpoint, since lwlock.c no longer needs to know anything about the LWLock needs of the higher-level SLRU facility. Ildus Kurbangaliev, reviewd by Álvaro Herrera and by me.
* Make sequential scans parallel-aware.Robert Haas2015-11-11
| | | | | | | | | | | | | | In addition, this path fills in a number of missing bits and pieces in the parallel infrastructure. Paths and plans now have a parallel_aware flag indicating whether whatever parallel-aware logic they have should be engaged. It is believed that we will need this flag for a number of path/plan types, not just sequential scans, which is why the flag is generic rather than part of the SeqScan structures specifically. Also, execParallel.c now gives parallel nodes a chance to initialize their PlanState nodes from the DSM during parallel worker startup. Amit Kapila, with a fair amount of adjustment by me. Review of previous patch versions by Haribabu Kommi and others.
* Update spelling of COPY optionsPeter Eisentraut2015-11-04
| | | | | The preferred spelling was changed from FORCE QUOTE to FORCE_QUOTE and the like, but some code was still referring to the old spellings.
* Fix problems with ParamListInfo serialization mechanism.Robert Haas2015-11-02
| | | | | | | | | | | | | | | | | | | | | | Commit d1b7c1ffe72e86932b5395f29e006c3f503bc53d introduced a mechanism for serializing a ParamListInfo structure to be passed to a parallel worker. However, this mechanism failed to handle external expanded values, as pointed out by Noah Misch. Repair. Moreover, plpgsql_param_fetch requires adjustment because the serialization mechanism needs it to skip evaluating unused parameters just as we would do when it is called from copyParamList, but params == estate->paramLI in that case. To fix, make the bms_is_member test in that function unconditional. Finally, have setup_param_list set a new ParamListInfo field, paramMask, to the parameters actually used in the expression, so that we don't try to fetch those that are not needed when serializing a parameter list. This isn't necessary for correctness, but it makes the performance of the parallel executor code comparable to what we do for cases involving cursors. Design suggestions and extensive review by Noah Misch. Patch by me.
* Message style improvementsPeter Eisentraut2015-10-28
| | | | | Message style, plurals, quoting, spelling, consistency with similar messages
* Add missing serial comma, for consistency.Robert Haas2015-10-28
| | | | Amit Langote, per Etsuro Fujita
* Fix incorrect message in ATWrongRelkindError.Robert Haas2015-10-28
| | | | | | Mistake introduced by commit 3bf3ab8c563699138be02f9dc305b7b77a724307. Etsuro Fujita
* Cleanup commit timestamp module activaction, againAlvaro Herrera2015-10-27
| | | | | | | | | | | | | Further tweak commit_ts.c so that on a standby the state is completely consistent with what that in the master, rather than behaving differently in the cases that the settings differ. Now in standby and master the module should always be active or inactive in lockstep. Author: Petr Jelínek, with some further tweaks by Álvaro Herrera. Backpatch to 9.5, where commit timestamps were introduced. Discussion: http://www.postgresql.org/message-id/5622BF9D.2010409@2ndquadrant.com
* Add two missing cases to ATWrongRelkindError.Robert Haas2015-10-22
| | | | | | | This way, we produce a better error message if someone tries to do something like ALTER INDEX .. ALTER COLUMN .. SET STORAGE. Amit Langote
* Fix a couple of bugs in recent parallelism-related commits.Robert Haas2015-10-22
| | | | | | | | | | | Commit 816e336f12ecabdc834d4cc31bcf966b2dd323dc added the wrong error check to async.c; sending restrictions is restricted to the leader, not altogether unsafe. Commit 3bd909b220930f21d6e15833a17947be749e7fde added ExecShutdownNode to traverse the planstate tree and call shutdown functions, but made a Gather node, the only node that actually has such a function, abort the tree traversal, which is wrong.
* Mark more functions parallel-restricted or parallel-unsafe.Robert Haas2015-10-16
| | | | | | | | | | | | | | | | | | Commit 7aea8e4f2daa4b39ca9d1309a0c4aadb0f7ed81b was overoptimistic about the degree of safety associated with running various functions in parallel mode. Functions that take a table name or OID as an argument are at least parallel-restricted, because the table might be temporary, and we currently don't allow parallel workers to touch temporary tables. Functions that take a query as an argument are outright unsafe, because the query could be anything, including a parallel-unsafe query. Also, the queue of pending notifications is backend-private, so adding to it from a worker doesn't behave correctly. We could fix this by transferring the worker's queue of pending notifications to the master during worker cleanup, but that seems like more trouble than it's worth for now. In addition to adjusting the pg_proc.h markings, also add an explicit check for this in async.c.
* Fix a problem with parallel workers being unable to restore role.Robert Haas2015-10-16
| | | | | | | | | check_role() tries to verify that the user has permission to become the requested role, but this is inappropriate in a parallel worker, which needs to exactly recreate the master's authorization settings. So skip the check in that case. This fixes a bug in commit 924bcf4f16d54c55310b28f77686608684734f42.
* Fix bogus commentsAlvaro Herrera2015-10-15
| | | | Author: Amit Langote
* ALTER TABLE .. FORCE ROW LEVEL SECURITYStephen Frost2015-10-04
| | | | | | | | | | | | | | | | | To allow users to force RLS to always be applied, even for table owners, add ALTER TABLE .. FORCE ROW LEVEL SECURITY. row_security=off overrides FORCE ROW LEVEL SECURITY, to ensure pg_dump output is complete (by default). Also add SECURITY_NOFORCE_RLS context to avoid data corruption when ALTER TABLE .. FORCE ROW SECURITY is being used. The SECURITY_NOFORCE_RLS security context is used only during referential integrity checks and is only considered in check_enable_rls() after we have already checked that the current user is the owner of the relation (which should always be the case during referential integrity checks). Back-patch to 9.5 where RLS was added.
* Add CASCADE support for CREATE EXTENSION.Andres Freund2015-10-03
| | | | | | | | | | | | | | | Without CASCADE, if an extension has an unfullfilled dependency on another extension, CREATE EXTENSION ERRORs out with "required extension ... is not installed". That is annoying, especially when that dependency is an implementation detail of the extension, rather than something the extension's user can make sense of. In addition to CASCADE this also includes a small set of regression tests around CREATE EXTENSION. Author: Petr Jelinek, editorialized by Michael Paquier, Andres Freund Reviewed-By: Michael Paquier, Andres Freund, Jeff Janes Discussion: 557E0520.3040800@2ndquadrant.com
* Fix errors in commit a04bb65f70dafdf462e0478ad19e6de56df89bfc.Tom Lane2015-09-30
| | | | Not a lot of commentary needed here really.
* Improve LISTEN startup time when there are many unread notifications.Tom Lane2015-09-30
| | | | | | | | | | | | | | | | If some existing listener is far behind, incoming new listener sessions would start from that session's read pointer and then need to advance over many already-committed notification messages, which they have no interest in. This was expensive in itself and also thrashed the pg_notify SLRU buffers a lot more than necessary. We can improve matters considerably in typical scenarios, without much added cost, by starting from the furthest-ahead read pointer, not the furthest-behind one. We do have to consider only sessions in our own database when doing this, which requires an extra field in the data structure, but that's a pretty small cost. Back-patch to 9.0 where the current LISTEN/NOTIFY logic was introduced. Matt Newell, slightly adjusted by me
* Add a Gather executor node.Robert Haas2015-09-30
| | | | | | | | | | | | | | | | | | | | | | | | 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.
* Small improvements in comments in async.c.Tom Lane2015-09-29
| | | | | | | | | We seem to have lost a line somewhere along the way in the comment block that discusses async.c's locks, because it suddenly refers to "both locks" without previously having mentioned more than one. Add a sentence to make that read more sanely. Also, refer to the "pos of the slowest backend" not the "tail of the slowest backend", since we have no per-backend value called "tail".
* COPY: use pg_plan_query() instead of planner()Alvaro Herrera2015-09-28
| | | | | While at it, trim the includes list in copy.c. The planner headers cannot be removed, but there are a few others that are not of any use.
* Remove legacy multixact truncation support.Andres Freund2015-09-26
| | | | | | | | | | | | | In 9.5 and master there is no need to support legacy truncation. This is just committed separately to make it easier to backpatch the WAL logged multixact truncation to 9.3 and 9.4 if we later decide to do so. I bumped master's magic from 0xD086 to 0xD088 and 9.5's from 0xD085 to 0xD087 to avoid 9.5 reusing a value that has been in use on master while keeping the numbers increasing between major versions. Discussion: 20150621192409.GA4797@alap3.anarazel.de Backpatch: 9.5
* Rework the way multixact truncations work.Andres Freund2015-09-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The fact that multixact truncations are not WAL logged has caused a fair share of problems. Amongst others it requires to do computations during recovery while the database is not in a consistent state, delaying truncations till checkpoints, and handling members being truncated, but offset not. We tried to put bandaids on lots of these issues over the last years, but it seems time to change course. Thus this patch introduces WAL logging for multixact truncations. This allows: 1) to perform the truncation directly during VACUUM, instead of delaying it to the checkpoint. 2) to avoid looking at the offsets SLRU for truncation during recovery, we can just use the master's values. 3) simplify a fair amount of logic to keep in memory limits straight, this has gotten much easier During the course of fixing this a bunch of additional bugs had to be fixed: 1) Data was not purged from memory the member's SLRU before deleting segments. This happened to be hard or impossible to hit due to the interlock between checkpoints and truncation. 2) find_multixact_start() relied on SimpleLruDoesPhysicalPageExist - but that doesn't work for offsets that haven't yet been flushed to disk. Add code to flush the SLRUs to fix. Not pretty, but it feels slightly safer to only make decisions based on actual on-disk state. 3) find_multixact_start() could be called concurrently with a truncation and thus fail. Via SetOffsetVacuumLimit() that could lead to a round of emergency vacuuming. The problem remains in pg_get_multixact_members(), but that's quite harmless. For now this is going to only get applied to 9.5+, leaving the issues in the older branches in place. It is quite possible that we need to backpatch at a later point though. For the case this gets backpatched we need to handle that an updated standby may be replaying WAL from a not-yet upgraded primary. We have to recognize that situation and use "old style" truncation (i.e. looking at the SLRUs) during WAL replay. In contrast to before, this now happens in the startup process, when replaying a checkpoint record, instead of the checkpointer. Doing truncation in the restartpoint is incorrect, they can happen much later than the original checkpoint, thereby leading to wraparound. To avoid "multixact_redo: unknown op code 48" errors standbys would have to be upgraded before primaries. A later patch will bump the WAL page magic, and remove the legacy truncation codepaths. Legacy truncation support is just included to make a possible future backpatch easier. Discussion: 20150621192409.GA4797@alap3.anarazel.de Reviewed-By: Robert Haas, Alvaro Herrera, Thomas Munro Backpatch: 9.5 for now
* Make ANALYZE compute basic statistics even for types with no "=" operator.Tom Lane2015-09-23
| | | | | | | | | | | | | | | | | Previously, ANALYZE simply ignored columns of datatypes that have neither a btree nor hash opclass (which means they have no recognized equality operator). Without a notion of equality, we can't identify most-common values nor estimate the number of distinct values. But we can still count nulls and compute the average physical column width, and those stats might be of value. Moreover there are some tools out there that don't work so well if rows are missing from pg_statistic. So let's add suitable logic for this case. While this is arguably a bug fix, it also has the potential to change query plans, and the gain seems not worth taking a risk of that in stable branches. So back-patch into 9.5 but not further. Oleksandr Shulgin, rewritten a bit by me.
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