27 Commits (225892552bd3052982d2b97b749e5945ea71facc)

Author	SHA1	Message	Date
Tom Lane	afb9249d06	Add support for doing late row locking in FDWs. ... Previously, FDWs could only do "early row locking", that is lock a row as soon as it's fetched, even though local restriction/join conditions might discard the row later. This patch adds callbacks that allow FDWs to do late locking in the same way that it's done for regular tables. To make use of this feature, an FDW must support the "ctid" column as a unique row identifier. Currently, since ctid has to be of type TID, the feature is of limited use, though in principle it could be used by postgres_fdw. We may eventually allow FDWs to specify another data type for ctid, which would make it possible for more FDWs to use this feature. This commit does not modify postgres_fdw to use late locking. We've tested some prototype code for that, but it's not in committable shape, and besides it's quite unclear whether it actually makes sense to do late locking against a remote server. The extra round trips required are likely to outweigh any benefit from improved concurrency. Etsuro Fujita, reviewed by Ashutosh Bapat, and hacked up a lot by me	11 years ago
Andres Freund	168d5805e4	Add support for INSERT ... ON CONFLICT DO NOTHING/UPDATE. ... The newly added ON CONFLICT clause allows to specify an alternative to raising a unique or exclusion constraint violation error when inserting. ON CONFLICT refers to constraints that can either be specified using a inference clause (by specifying the columns of a unique constraint) or by naming a unique or exclusion constraint. DO NOTHING avoids the constraint violation, without touching the pre-existing row. DO UPDATE SET ... [WHERE ...] updates the pre-existing tuple, and has access to both the tuple proposed for insertion and the existing tuple; the optional WHERE clause can be used to prevent an update from being executed. The UPDATE SET and WHERE clauses have access to the tuple proposed for insertion using the "magic" EXCLUDED alias, and to the pre-existing tuple using the table name or its alias. This feature is often referred to as upsert. This is implemented using a new infrastructure called "speculative insertion". It is an optimistic variant of regular insertion that first does a pre-check for existing tuples and then attempts an insert. If a violating tuple was inserted concurrently, the speculatively inserted tuple is deleted and a new attempt is made. If the pre-check finds a matching tuple the alternative DO NOTHING or DO UPDATE action is taken. If the insertion succeeds without detecting a conflict, the tuple is deemed inserted. To handle the possible ambiguity between the excluded alias and a table named excluded, and for convenience with long relation names, INSERT INTO now can alias its target table. Bumps catversion as stored rules change. Author: Peter Geoghegan, with significant contributions from Heikki Linnakangas and Andres Freund. Testing infrastructure by Jeff Janes. Reviewed-By: Heikki Linnakangas, Andres Freund, Robert Haas, Simon Riggs, Dean Rasheed, Stephen Frost and many others.	11 years ago
Tom Lane	cb1ca4d800	Allow foreign tables to participate in inheritance. ... Foreign tables can now be inheritance children, or parents. Much of the system was already ready for this, but we had to fix a few things of course, mostly in the area of planner and executor handling of row locks. As side effects of this, allow foreign tables to have NOT VALID CHECK constraints (and hence to accept ALTER ... VALIDATE CONSTRAINT), and to accept ALTER SET STORAGE and ALTER SET WITH/WITHOUT OIDS. Continuing to disallow these things would've required bizarre and inconsistent special cases in inheritance behavior. Since foreign tables don't enforce CHECK constraints anyway, a NOT VALID one is a complete no-op, but that doesn't mean we shouldn't allow it. And it's possible that some FDWs might have use for SET STORAGE or SET WITH OIDS, though doubtless they will be no-ops for most. An additional change in support of this is that when a ModifyTable node has multiple target tables, they will all now be explicitly identified in EXPLAIN output, for example: Update on pt1 (cost=0.00..321.05 rows=3541 width=46) Update on pt1 Foreign Update on ft1 Foreign Update on ft2 Update on child3 -> Seq Scan on pt1 (cost=0.00..0.00 rows=1 width=46) -> Foreign Scan on ft1 (cost=100.00..148.03 rows=1170 width=46) -> Foreign Scan on ft2 (cost=100.00..148.03 rows=1170 width=46) -> Seq Scan on child3 (cost=0.00..25.00 rows=1200 width=46) This was done mainly to provide an unambiguous place to attach "Remote SQL" fields, but it is useful for inherited updates even when no foreign tables are involved. Shigeru Hanada and Etsuro Fujita, reviewed by Ashutosh Bapat and Kyotaro Horiguchi, some additional hacking by me	11 years ago
Bruce Momjian	4baaf863ec	Update copyright for 2015 ... Backpatch certain files through 9.0	11 years ago
Tom Lane	2db576ba8c	Fix corner case where SELECT FOR UPDATE could return a row twice. ... In READ COMMITTED mode, if a SELECT FOR UPDATE discovers it has to redo WHERE-clause checking on rows that have been updated since the SELECT's snapshot, it invokes EvalPlanQual processing to do that. If this first occurs within a non-first child table of an inheritance tree, the previous coding could accidentally re-return a matching row from an earlier, already-scanned child table. (And, to add insult to injury, I think this could make it miss returning a row that should have been returned, if the updated row that this happens on should still have passed the WHERE qual.) Per report from Kyotaro Horiguchi; the added isolation test is based on his test case. This has been broken for quite awhile, so back-patch to all supported branches.	11 years ago
Alvaro Herrera	df630b0dd5	Implement SKIP LOCKED for row-level locks ... This clause changes the behavior of SELECT locking clauses in the presence of locked rows: instead of causing a process to block waiting for the locks held by other processes (or raise an error, with NOWAIT), SKIP LOCKED makes the new reader skip over such rows. While this is not appropriate behavior for general purposes, there are some cases in which it is useful, such as queue-like tables. Catalog version bumped because this patch changes the representation of stored rules. Reviewed by Craig Ringer (based on a previous attempt at an implementation by Simon Riggs, who also provided input on the syntax used in the current patch), David Rowley, and Álvaro Herrera. Author: Thomas Munro	11 years ago
Alvaro Herrera	1c9701cfe5	Fix FOR UPDATE NOWAIT on updated tuple chains ... If SELECT FOR UPDATE NOWAIT tries to lock a tuple that is concurrently being updated, it might fail to honor its NOWAIT specification and block instead of raising an error. Fix by adding a no-wait flag to EvalPlanQualFetch which it can pass down to heap_lock_tuple; also use it in EvalPlanQualFetch itself to avoid blocking while waiting for a concurrent transaction. Authors: Craig Ringer and Thomas Munro, tweaked by Álvaro http://www.postgresql.org/message-id/51FB6703.9090801@2ndquadrant.com Per Thomas Munro in the course of his SKIP LOCKED feature submission, who also provided one of the isolation test specs. Backpatch to 9.4, because that's as far back as it applies without conflicts (although the bug goes all the way back). To that branch also backpatch Thomas Munro's new NOWAIT test cases, committed in master by Heikki as commit 9ee16b49f0 .	11 years ago
Bruce Momjian	0a78320057	pgindent run for 9.4 ... This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.	12 years ago
Bruce Momjian	7e04792a1c	Update copyright for 2014 ... Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.	12 years ago
Bruce Momjian	9af4159fce	pgindent run for release 9.3 ... This is the first run of the Perl-based pgindent script. Also update pgindent instructions.	12 years ago
Alvaro Herrera	0ac5ad5134	Improve concurrency of foreign key locking ... This patch introduces two additional lock modes for tuples: "SELECT FOR KEY SHARE" and "SELECT FOR NO KEY UPDATE". These don't block each other, in contrast with already existing "SELECT FOR SHARE" and "SELECT FOR UPDATE". UPDATE commands that do not modify the values stored in the columns that are part of the key of the tuple now grab a SELECT FOR NO KEY UPDATE lock on the tuple, allowing them to proceed concurrently with tuple locks of the FOR KEY SHARE variety. Foreign key triggers now use FOR KEY SHARE instead of FOR SHARE; this means the concurrency improvement applies to them, which is the whole point of this patch. The added tuple lock semantics require some rejiggering of the multixact module, so that the locking level that each transaction is holding can be stored alongside its Xid. Also, multixacts now need to persist across server restarts and crashes, because they can now represent not only tuple locks, but also tuple updates. This means we need more careful tracking of lifetime of pg_multixact SLRU files; since they now persist longer, we require more infrastructure to figure out when they can be removed. pg_upgrade also needs to be careful to copy pg_multixact files over from the old server to the new, or at least part of multixact.c state, depending on the versions of the old and new servers. Tuple time qualification rules (HeapTupleSatisfies routines) need to be careful not to consider tuples with the "is multi" infomask bit set as being only locked; they might need to look up MultiXact values (i.e. possibly do pg_multixact I/O) to find out the Xid that updated a tuple, whereas they previously were assured to only use information readily available from the tuple header. This is considered acceptable, because the extra I/O would involve cases that would previously cause some commands to block waiting for concurrent transactions to finish. Another important change is the fact that locking tuples that have previously been updated causes the future versions to be marked as locked, too; this is essential for correctness of foreign key checks. This causes additional WAL-logging, also (there was previously a single WAL record for a locked tuple; now there are as many as updated copies of the tuple there exist.) With all this in place, contention related to tuples being checked by foreign key rules should be much reduced. As a bonus, the old behavior that a subtransaction grabbing a stronger tuple lock than the parent (sub)transaction held on a given tuple and later aborting caused the weaker lock to be lost, has been fixed. Many new spec files were added for isolation tester framework, to ensure overall behavior is sane. There's probably room for several more tests. There were several reviewers of this patch; in particular, Noah Misch and Andres Freund spent considerable time in it. Original idea for the patch came from Simon Riggs, after a problem report by Joel Jacobson. Most code is from me, with contributions from Marti Raudsepp, Alexander Shulgin, Noah Misch and Andres Freund. This patch was discussed in several pgsql-hackers threads; the most important start at the following message-ids: AANLkTimo9XVcEzfiBR-ut3KVNDkjm2Vxh+t8kAmWjPuv@mail.gmail.com 1290721684-sup-3951@alvh.no-ip.org 1294953201-sup-2099@alvh.no-ip.org 1320343602-sup-2290@alvh.no-ip.org 1339690386-sup-8927@alvh.no-ip.org 4FE5FF020200002500048A3D@gw.wicourts.gov 4FEAB90A0200002500048B7D@gw.wicourts.gov	13 years ago
Bruce Momjian	bd61a623ac	Update copyrights for 2013 ... Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.	13 years ago
Kevin Grittner	6868ed7491	Throw error if expiring tuple is again updated or deleted. ... This prevents surprising behavior when a FOR EACH ROW trigger BEFORE UPDATE or BEFORE DELETE directly or indirectly updates or deletes the the old row. Prior to this patch the requested action on the row could be silently ignored while all triggered actions based on the occurence of the requested action could be committed. One example of how this could happen is if the BEFORE DELETE trigger for a "parent" row deleted "children" which had trigger functions to update summary or status data on the parent. This also prevents similar surprising problems if the query has a volatile function which updates a target row while it is already being updated. There are related issues present in FOR UPDATE cursors and READ COMMITTED queries which are not handled by this patch. These issues need further evalution to determine what change, if any, is needed. Where the new error messages are generated, in most cases the best fix will be to move code from the BEFORE trigger to an AFTER trigger. Where this is not feasible, the trigger can avoid the error by re-issuing the triggering statement and returning NULL. Documentation changes will be submitted in a separate patch. Kevin Grittner and Tom Lane with input from Florian Pflug and Robert Haas, based on problems encountered during conversion of Wisconsin Circuit Court trigger logic to plpgsql triggers.	13 years ago
Alvaro Herrera	c219d9b0a5	Split tuple struct defs from htup.h to htup_details.h ... This reduces unnecessary exposure of other headers through htup.h, which is very widely included by many files. I have chosen to move the function prototypes to the new file as well, because that means htup.h no longer needs to include tupdesc.h. In itself this doesn't have much effect in indirect inclusion of tupdesc.h throughout the tree, because it's also required by execnodes.h; but it's something to explore in the future, and it seemed best to do the htup.h change now while I'm busy with it.	13 years ago
Bruce Momjian	e126958c2e	Update copyright notices for year 2012.	14 years ago
Alvaro Herrera	b93f5a5673	Move Trigger and TriggerDesc structs out of rel.h into a new reltrigger.h ... This lets us stop including rel.h into execnodes.h, which is a widely used header.	14 years ago
Bruce Momjian	bf50caf105	pgindent run before PG 9.1 beta 1.	15 years ago
Tom Lane	d487afbb81	Fix PlanRowMark/ExecRowMark structures to handle inheritance correctly. ... In an inherited UPDATE/DELETE, each target table has its own subplan, because it might have a column set different from other targets. This means that the resjunk columns we add to support EvalPlanQual might be at different physical column numbers in each subplan. The EvalPlanQual rewrite I did for 9.0 failed to account for this, resulting in possible misbehavior or even crashes during concurrent updates to the same row, as seen in a recent report from Gordon Shannon. Revise the data structure so that we track resjunk column numbers separately for each subplan. I also chose to move responsibility for identifying the physical column numbers back to executor startup, instead of assuming that numbers derived during preprocess_targetlist would stay valid throughout subsequent massaging of the plan. That's a bit slower, so we might want to consider undoing it someday; but it would complicate the patch considerably and didn't seem justifiable in a bug fix that has to be back-patched to 9.0.	15 years ago
Bruce Momjian	5d950e3b0c	Stamp copyrights for year 2011.	15 years ago
Magnus Hagander	9f2e211386	Remove cvs keywords from all files.	15 years ago
Joe Conway	5eb15c9942	SERIALIZABLE transactions are actually implemented beneath the covers with ... transaction snapshots, i.e. a snapshot registered at the beginning of a transaction. Change variable naming and comments to reflect this reality in preparation for a future, truly serializable mode, e.g. Serializable Snapshot Isolation (SSI). For the moment transaction snapshots are still used to implement SERIALIZABLE, but hopefully not for too much longer. Patch by Kevin Grittner and Dan Ports with review and some minor wording changes by me.	15 years ago
Tom Lane	77c75076f3	Fix oversight in new EvalPlanQual logic: the second loop over the ExecRowMark ... list in ExecLockRows() forgot to allow for the possibility that some of the rowmarks are for child tables that aren't relevant to the current row. Per report from Kenichiro Tanaka.	15 years ago
Tom Lane	53e757689c	Make NestLoop plan nodes pass outer-relation variables into their inner ... relation using the general PARAM_EXEC executor parameter mechanism, rather than the ad-hoc kluge of passing the outer tuple down through ExecReScan. The previous method was hard to understand and could never be extended to handle parameters coming from multiple join levels. This patch doesn't change the set of possible plans nor have any significant performance effect, but it's necessary infrastructure for future generalization of the concept of an inner indexscan plan. ExecReScan's second parameter is now unused, so it's removed.	15 years ago
Bruce Momjian	65e806cba1	pgindent run for 9.0	16 years ago
Bruce Momjian	0239800893	Update copyright for the year 2010.	16 years ago
Tom Lane	9f2ee8f287	Re-implement EvalPlanQual processing to improve its performance and eliminate ... a lot of strange behaviors that occurred in join cases. We now identify the "current" row for every joined relation in UPDATE, DELETE, and SELECT FOR UPDATE/SHARE queries. If an EvalPlanQual recheck is necessary, we jam the appropriate row into each scan node in the rechecking plan, forcing it to emit only that one row. The former behavior could rescan the whole of each joined relation for each recheck, which was terrible for performance, and what's much worse could result in duplicated output tuples. Also, the original implementation of EvalPlanQual could not re-use the recheck execution tree --- it had to go through a full executor init and shutdown for every row to be tested. To avoid this overhead, I've associated a special runtime Param with each LockRows or ModifyTable plan node, and arranged to make every scan node below such a node depend on that Param. Thus, by signaling a change in that Param, the EPQ machinery can just rescan the already-built test plan. This patch also adds a prohibition on set-returning functions in the targetlist of SELECT FOR UPDATE/SHARE. This is needed to avoid the duplicate-output-tuple problem. It seems fairly reasonable since the other restrictions on SELECT FOR UPDATE are meant to ensure that there is a unique correspondence between source tuples and result tuples, which an output SRF destroys as much as anything else does.	16 years ago
Tom Lane	0adaf4cb31	Move the handling of SELECT FOR UPDATE locking and rechecking out of ... 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.	16 years ago