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path: root/src/backend/commands/trigger.c
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2012-08-30Split tuple struct defs from htup.h to htup_details.hAlvaro Herrera
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.
2012-08-10Centralize the logic for detecting misplaced aggregates, window funcs, etc.Tom Lane
Formerly we relied on checking after-the-fact to see if an expression contained aggregates, window functions, or sub-selects when it shouldn't. This is grotty, easily forgotten (indeed, we had forgotten to teach DefineIndex about rejecting window functions), and none too efficient since it requires extra traversals of the parse tree. To improve matters, define an enum type that classifies all SQL sub-expressions, store it in ParseState to show what kind of expression we are currently parsing, and make transformAggregateCall, transformWindowFuncCall, and transformSubLink check the expression type and throw error if the type indicates the construct is disallowed. This allows removal of a large number of ad-hoc checks scattered around the code base. The enum type is sufficiently fine-grained that we can still produce error messages of at least the same specificity as before. Bringing these error checks together revealed that we'd been none too consistent about phrasing of the error messages, so standardize the wording a bit. Also, rewrite checking of aggregate arguments so that it requires only one traversal of the arguments, rather than up to three as before. In passing, clean up some more comments left over from add_missing_from support, and annotate some tests that I think are dead code now that that's gone. (I didn't risk actually removing said dead code, though.)
2012-07-20connoinherit may be true only for CHECK constraintsAlvaro Herrera
The code was setting it true for other constraints, which is bogus. Doing so caused bogus catalog entries for such constraints, and in particular caused an error to be raised when trying to drop a constraint of types other than CHECK from a table that has children, such as reported in bug #6712. In 9.2, additionally ignore connoinherit=true for other constraint types, to avoid having to force initdb; existing databases might already contain bogus catalog entries. Includes a catversion bump (in HEAD only). Bug report from Miroslav Ć ulc Analysis from Amit Kapila and Noah Misch; Amit also contributed the patch.
2012-07-20Make new event trigger facility actually do something.Robert Haas
Commit 3855968f328918b6cd1401dd11d109d471a54d40 added syntax, pg_dump, psql support, and documentation, but the triggers didn't actually fire. With this commit, they now do. This is still a pretty basic facility overall because event triggers do not get a whole lot of information about what the user is trying to do unless you write them in C; and there's still no option to fire them anywhere except at the very beginning of the execution sequence, but it's better than nothing, and a good building block for future work. Along the way, add a regression test for ALTER LARGE OBJECT, since testing of event triggers reveals that we haven't got one. Dimitri Fontaine and Robert Haas
2012-06-25Replace int2/int4 in C code with int16/int32Peter Eisentraut
The latter was already the dominant use, and it's preferable because in C the convention is that intXX means XX bits. Therefore, allowing mixed use of int2, int4, int8, int16, int32 is obviously confusing. Remove the typedefs for int2 and int4 for now. They don't seem to be widely used outside of the PostgreSQL source tree, and the few uses can probably be cleaned up by the time this ships.
2012-06-19Improve tests for whether we can skip queueing RI enforcement triggers.Tom Lane
During an update of a PK row, we can skip firing the RI trigger if any old key value is NULL, because then the row could not have had any matching rows in the FK table. Conversely, during an update of an FK row, the outcome is determined if any new key value is NULL. In either case it becomes unnecessary to compare individual key values. This patch was inspired by discussion of Vik Reykja's patch to use IS NOT DISTINCT semantics for the key comparisons. In the event there is no need for that and so this patch looks nothing like his, but he should still get credit for having re-opened consideration of the trigger skip logic.
2012-06-17Refer to the default foreign key match style as MATCH SIMPLE internally.Tom Lane
Previously we followed the SQL92 wording, "MATCH <unspecified>", but since SQL99 there's been a less awkward way to refer to the default style. In addition to the code changes, pg_constraint.confmatchtype now stores this match style as 's' (SIMPLE) rather than 'u' (UNSPECIFIED). This doesn't affect pg_dump or psql because they use pg_get_constraintdef() to reconstruct foreign key definitions. But other client-side code might examine that column directly, so this change will have to be marked as an incompatibility in the 9.3 release notes.
2012-06-10Run pgindent on 9.2 source tree in preparation for first 9.3Bruce Momjian
commit-fest.
2012-04-20Recast "ONLY" column CHECK constraints as NO INHERITAlvaro Herrera
The original syntax wasn't universally loved, and it didn't allow its usage in CREATE TABLE, only ALTER TABLE. It now works everywhere, and it also allows using ALTER TABLE ONLY to add an uninherited CHECK constraint, per discussion. The pg_constraint column has accordingly been renamed connoinherit. This commit partly reverts some of the changes in 61d81bd28dbec65a6b144e0cd3d0bfe25913c3ac, particularly some pg_dump and psql bits, because now pg_get_constraintdef includes the necessary NO INHERIT within the constraint definition. Author: Nikhil Sontakke Some tweaks by me
2012-03-09Extend object access hook framework to support arguments, and DROP.Robert Haas
This allows loadable modules to get control at drop time, perhaps for the purpose of performing additional security checks or to log the event. The initial purpose of this code is to support sepgsql, but other applications should be possible as well. KaiGai Kohei, reviewed by me.
2012-02-23Require execute permission on the trigger function for CREATE TRIGGER.Tom Lane
This check was overlooked when we added function execute permissions to the system years ago. For an ordinary trigger function it's not a big deal, since trigger functions execute with the permissions of the table owner, so they couldn't do anything the user issuing the CREATE TRIGGER couldn't have done anyway. However, if a trigger function is SECURITY DEFINER, that is not the case. The lack of checking would allow another user to install it on his own table and then invoke it with, essentially, forged input data; which the trigger function is unlikely to realize, so it might do something undesirable, for instance insert false entries in an audit log table. Reported by Dinesh Kumar, patch by Robert Haas Security: CVE-2012-0866
2012-01-25Add pg_trigger_depth() functionAlvaro Herrera
This reports the depth level of triggers currently in execution, or zero if not called from inside a trigger. No catversion bump in this patch, but you have to initdb if you want access to the new function. Author: Kevin Grittner
2012-01-01Update copyright notices for year 2012.Bruce Momjian
2011-12-19Allow CHECK constraints to be declared ONLYAlvaro Herrera
This makes them enforceable only on the parent table, not on children tables. This is useful in various situations, per discussion involving people bitten by the restrictive behavior introduced in 8.4. Message-Id: 8762mp93iw.fsf@comcast.net CAFaPBrSMMpubkGf4zcRL_YL-AERUbYF_-ZNNYfb3CVwwEqc9TQ@mail.gmail.com Authors: Nikhil Sontakke, Alex Hunsaker Reviewed by Robert Haas and myself
2011-12-15Improve behavior of concurrent rename statements.Robert Haas
Previously, renaming a table, sequence, view, index, foreign table, column, or trigger checked permissions before locking the object, which meant that if permissions were revoked during the lock wait, we would still allow the operation. Similarly, if the original object is dropped and a new one with the same name is created, the operation will be allowed if we had permissions on the old object; the permissions on the new object don't matter. All this is now fixed. Along the way, attempting to rename a trigger on a foreign table now gives the same error message as trying to create one there in the first place (i.e. that it's not a table or view) rather than simply stating that no trigger by that name exists. Patch by me; review by Noah Misch.
2011-11-30Improve table locking behavior in the face of current DDL.Robert Haas
In the previous coding, callers were faced with an awkward choice: look up the name, do permissions checks, and then lock the table; or look up the name, lock the table, and then do permissions checks. The first choice was wrong because the results of the name lookup and permissions checks might be out-of-date by the time the table lock was acquired, while the second allowed a user with no privileges to interfere with access to a table by users who do have privileges (e.g. if a malicious backend queues up for an AccessExclusiveLock on a table on which AccessShareLock is already held, further attempts to access the table will be blocked until the AccessExclusiveLock is obtained and the malicious backend's transaction rolls back). To fix, allow callers of RangeVarGetRelid() to pass a callback which gets executed after performing the name lookup but before acquiring the relation lock. If the name lookup is retried (because invalidation messages are received), the callback will be re-executed as well, so we get the best of both worlds. RangeVarGetRelid() is renamed to RangeVarGetRelidExtended(); callers not wishing to supply a callback can continue to invoke it as RangeVarGetRelid(), which is now a macro. Since the only one caller that uses nowait = true now passes a callback anyway, the RangeVarGetRelid() macro defaults nowait as well. The callback can also be used for supplemental locking - for example, REINDEX INDEX needs to acquire the table lock before the index lock to reduce deadlock possibilities. There's a lot more work to be done here to fix all the cases where this can be a problem, but this commit provides the general infrastructure and fixes the following specific cases: REINDEX INDEX, REINDEX TABLE, LOCK TABLE, and and DROP TABLE/INDEX/SEQUENCE/VIEW/FOREIGN TABLE. Per discussion with Noah Misch and Alvaro Herrera.
2011-11-17Further consolidation of DROP statement handling.Robert Haas
This gets rid of an impressive amount of duplicative code, with only minimal behavior changes. DROP FOREIGN DATA WRAPPER now requires object ownership rather than superuser privileges, matching the documentation we already have. We also eliminate the historical warning about dropping a built-in function as unuseful. All operations are now performed in the same order for all object types handled by dropcmds.c. KaiGai Kohei, with minor revisions by me
2011-10-21More cleanup after failed reduced-lock-levels-for-DDL feature.Tom Lane
Turns out that use of ShareUpdateExclusiveLock or ShareRowExclusiveLock to protect DDL changes had gotten copied into several places that were not touched by either of Simon's original patches for the feature, and thus neither he nor I thought to revert them. (Indeed, it appears that two of these uses were committed *after* the reversion, which just goes to show that git merging is no panacea.) Change these places to use AccessExclusiveLock again. If we ever manage to resurrect that feature, we're going to have to think a bit harder about how to keep lock level usage in sync for DDL operations that aren't within the AlterTable infrastructure. Two of these bugs are only in HEAD, but one is in the 9.1 branch too. Alvaro found one of them, I found the other two.
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).
2011-09-22Make 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
2011-08-21Fix trigger WHEN conditions when both BEFORE and AFTER triggers exist.Tom Lane
Due to tuple-slot mismanagement, evaluation of WHEN conditions for AFTER ROW UPDATE triggers could crash if there had been a BEFORE ROW trigger fired for the same update. Fix by not trying to overload the use of estate->es_trig_tuple_slot. Per report from Yoran Heling. Back-patch to 9.0, when trigger WHEN conditions were introduced.
2011-07-16Replace errdetail("%s", ...) with errdetail_internal("%s", ...).Tom Lane
There may be some other places where we should use errdetail_internal, but they'll have to be evaluated case-by-case. This commit just hits a bunch of places where invoking gettext is obviously a waste of cycles.
2011-07-12Avoid listing ungrouped Vars in the targetlist of Agg-underneath-Window.Tom Lane
Regular aggregate functions in combination with, or within the arguments of, window functions are OK per spec; they have the semantics that the aggregate output rows are computed and then we run the window functions over that row set. (Thus, this combination is not really useful unless there's a GROUP BY so that more than one aggregate output row is possible.) The case without GROUP BY could fail, as recently reported by Jeff Davis, because sloppy construction of the Agg node's targetlist resulted in extra references to possibly-ungrouped Vars appearing outside the aggregate function calls themselves. See the added regression test case for an example. Fixing this requires modifying the API of flatten_tlist and its underlying function pull_var_clause. I chose to make pull_var_clause's API for aggregates identical to what it was already doing for placeholders, since the useful behaviors turn out to be the same (error, report node as-is, or recurse into it). I also tightened the error checking in this area a bit: if it was ever valid to see an uplevel Var, Aggref, or PlaceHolderVar here, that was a long time ago, so complain instead of ignoring them. Backpatch into 9.1. The failure exists in 8.4 and 9.0 as well, but seeing that it only occurs in a basically-useless corner case, it doesn't seem worth the risks of changing a function API in a minor release. There might be third-party code using pull_var_clause.
2011-07-08Try to acquire relation locks in RangeVarGetRelid.Robert Haas
In the previous coding, we would look up a relation in RangeVarGetRelid, lock the resulting OID, and then AcceptInvalidationMessages(). While this was sufficient to ensure that we noticed any changes to the relation definition before building the relcache entry, it didn't handle the possibility that the name we looked up no longer referenced the same OID. This was particularly problematic in the case where a table had been dropped and recreated: we'd latch on to the entry for the old relation and fail later on. Now, we acquire the relation lock inside RangeVarGetRelid, and retry the name lookup if we notice that invalidation messages have been processed meanwhile. Many operations that would previously have failed with an error in the presence of concurrent DDL will now succeed. There is a good deal of work remaining to be done here: many callers of RangeVarGetRelid still pass NoLock for one reason or another. In addition, nothing in this patch guards against the possibility that the meaning of an unqualified name might change due to the creation of a relation in a schema earlier in the user's search path than the one where it was previously found. Furthermore, there's nothing at all here to guard against similar race conditions for non-relations. For all that, it's a start. Noah Misch and Robert Haas
2011-07-07Finish disabling reduced-lock-levels-for-DDL feature.Tom Lane
Previous patch only covered the ALTER TABLE changes, not changes in other commands; and it neglected to revert the documentation changes.
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.
2011-06-15Rework parsing of ConstraintAttributeSpec to improve NOT VALID handling.Tom Lane
The initial commit of the ALTER TABLE ADD FOREIGN KEY NOT VALID feature failed to support labeling such constraints as deferrable. The best fix for this seems to be to fold NOT VALID into ConstraintAttributeSpec. That's a bit more general than the documented syntax, but it allows better-targeted syntax error messages. In addition, do some mostly-but-not-entirely-cosmetic code review for the whole NOT VALID patch.
2011-04-12Pass collations to functions in FunctionCallInfoData, not FmgrInfo.Tom Lane
Since collation is effectively an argument, not a property of the function, FmgrInfo is really the wrong place for it; and this becomes critical in cases where a cached FmgrInfo is used for varying purposes that might need different collation settings. Fix by passing it in FunctionCallInfoData instead. In particular this allows a clean fix for bug #5970 (record_cmp not working). This requires touching a bit more code than the original method, but nobody ever thought that collations would not be an invasive patch...
2011-04-10pgindent run before PG 9.1 beta 1.Bruce Momjian
2011-04-07Fix collations when we call transformWhereClause from outside the parser.Tom Lane
Previous patches took care of assorted places that call transformExpr from outside the main parser, but I overlooked the fact that some places use transformWhereClause as a shortcut for transformExpr + coerce_to_boolean. In particular this broke collation-sensitive index WHERE clauses, as per report from Thom Brown. Trigger WHEN and rule WHERE clauses too. I'm not forcing initdb for this fix, but any affected indexes, triggers, or rules will need to be dropped and recreated.
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.
2011-02-21Fix dangling-pointer problem in before-row update trigger processing.Tom Lane
ExecUpdate checked for whether ExecBRUpdateTriggers had returned a new tuple value by seeing if the returned tuple was pointer-equal to the old one. But the "old one" was in estate->es_junkFilter's result slot, which would be scribbled on if we had done an EvalPlanQual update in response to a concurrent update of the target tuple; therefore we were comparing a dangling pointer to a live one. Given the right set of circumstances we could get a false match, resulting in not forcing the tuple to be stored in the slot we thought it was stored in. In the case reported by Maxim Boguk in bug #5798, this led to "cannot extract system attribute from virtual tuple" failures when trying to do "RETURNING ctid". I believe there is a very-low-probability chance of more serious errors, such as generating incorrect index entries based on the original rather than the trigger-modified version of the row. In HEAD, change all of ExecBRInsertTriggers, ExecIRInsertTriggers, ExecBRUpdateTriggers, and ExecIRUpdateTriggers so that they continue to have similar APIs. In the back branches I just changed ExecBRUpdateTriggers, since there is no bug in the ExecBRInsertTriggers case.
2011-02-08Extend ALTER TABLE to allow Foreign Keys to be added without initial validation.Simon Riggs
FK constraints that are marked NOT VALID may later be VALIDATED, which uses an ShareUpdateExclusiveLock on constraint table and RowShareLock on referenced table. Significantly reduces lock strength and duration when adding FKs. New state visible from psql. Simon Riggs, with reviews from Marko Tiikkaja and Robert Haas
2011-01-01Stamp copyrights for year 2011.Bruce Momjian
2010-11-25Object access hook framework, with post-creation hook.Robert Haas
After a SQL object is created, we provide an opportunity for security or logging plugins to get control; for example, a security label provider could use this to assign an initial security label to newly created objects. The basic infrastructure is (hopefully) reusable for other types of events that might require similar treatment. KaiGai Kohei, with minor adjustments.
2010-10-10Support triggers on views.Tom Lane
This patch adds the SQL-standard concept of an INSTEAD OF trigger, which is fired instead of performing a physical insert/update/delete. The trigger function is passed the entire old and/or new rows of the view, and must figure out what to do to the underlying tables to implement the update. So this feature can be used to implement updatable views using trigger programming style rather than rule hacking. In passing, this patch corrects the names of some columns in the information_schema.triggers view. It seems the SQL committee renamed them somewhere between SQL:99 and SQL:2003. Dean Rasheed, reviewed by Bernd Helmle; some additional hacking by me.
2010-09-20Remove cvs keywords from all files.Magnus Hagander
2010-09-11SERIALIZABLE transactions are actually implemented beneath the covers withJoe Conway
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.
2010-08-19Fix possible corruption of AfterTriggerEventLists in subtransaction rollback.Tom Lane
afterTriggerInvokeEvents failed to adjust events->tailfree when truncating the last chunk of an event list. This could result in the data being "de-truncated" by afterTriggerRestoreEventList during a subsequent subtransaction abort. Even that wouldn't kill us, because the re-added data would just be events marked DONE --- unless the data had been partially overwritten by new events. Then we might crash, or in any case misbehave (perhaps fire triggers twice, or fire triggers with the wrong event data). Per bug #5622 from Thue Janus Kristensen. Back-patch to 8.4 where the current trigger list representation was introduced.
2010-08-05Standardize get_whatever_oid functions for other object types.Robert Haas
- Rename TSParserGetPrsid to get_ts_parser_oid. - Rename TSDictionaryGetDictid to get_ts_dict_oid. - Rename TSTemplateGetTmplid to get_ts_template_oid. - Rename TSConfigGetCfgid to get_ts_config_oid. - Rename FindConversionByName to get_conversion_oid. - Rename GetConstraintName to get_constraint_oid. - Add new functions get_opclass_oid, get_opfamily_oid, get_rewrite_oid, get_rewrite_oid_without_relid, get_trigger_oid, and get_cast_oid. The name of each function matches the corresponding catalog. Thanks to KaiGai Kohei for the review.
2010-07-28Reduce lock levels of CREATE TRIGGER and some ALTER TABLE, CREATE RULE actions.Simon Riggs
Avoid hard-coding lockmode used for many altering DDL commands, allowing easier future changes of lock levels. Implementation of initial analysis on DDL sub-commands, so that many lock levels are now at ShareUpdateExclusiveLock or ShareRowExclusiveLock, allowing certain DDL not to block reads/writes. First of number of planned changes in this area; additional docs required when full project complete.
2010-02-26pgindent run for 9.0Bruce Momjian
2010-02-14Wrap calls to SearchSysCache and related functions using macros.Robert Haas
The purpose of this change is to eliminate the need for every caller of SearchSysCache, SearchSysCacheCopy, SearchSysCacheExists, GetSysCacheOid, and SearchSysCacheList to know the maximum number of allowable keys for a syscache entry (currently 4). This will make it far easier to increase the maximum number of keys in a future release should we choose to do so, and it makes the code shorter, too. Design and review by Tom Lane.
2010-01-24Fix assorted core dumps and Assert failures that could occur duringTom Lane
AbortTransaction or AbortSubTransaction, when trying to clean up after an error that prevented (sub)transaction start from completing: * access to TopTransactionResourceOwner that might not exist * assert failure in AtEOXact_GUC, if AtStart_GUC not called yet * assert failure or core dump in AfterTriggerEndSubXact, if AfterTriggerBeginSubXact not called yet Per testing by injecting elog(ERROR) at successive steps in StartTransaction and StartSubTransaction. It's not clear whether all of these cases could really occur in the field, but at least one of them is easily exposed by simple stress testing, as per my accidental discovery yesterday.
2010-01-17Improve the handling of SET CONSTRAINTS commands by having them searchTom Lane
pg_constraint before searching pg_trigger. This allows saner handling of corner cases; in particular we now say "constraint is not deferrable" rather than "constraint does not exist" when the command is applied to a constraint that's inherently non-deferrable. Per a gripe several months ago from hubert depesz lubaczewski. To make this work without breaking user-defined constraint triggers, we have to add entries for them to pg_constraint. However, in return we can remove the pgconstrname column from pg_constraint, which represents a fairly sizable space savings. I also replaced the tgisconstraint column with tgisinternal; the old meaning of tgisconstraint can now be had by testing for nonzero tgconstraint, while there is no other way to get the old meaning of nonzero tgconstraint, namely that the trigger was internally generated rather than being user-created. In passing, fix an old misstatement in the docs and comments, namely that pg_trigger.tgdeferrable is exactly redundant with pg_constraint.condeferrable. Actually, we mark RI action triggers as nondeferrable even when they belong to a nominally deferrable FK constraint. The SET CONSTRAINTS code now relies on that instead of hard-coding a list of exception OIDs.
2010-01-02Update copyright for the year 2010.Bruce Momjian
2009-11-20Add a WHEN clause to CREATE TRIGGER, allowing a boolean expression to beTom Lane
checked to determine whether the trigger should be fired. For BEFORE triggers this is mostly a matter of spec compliance; but for AFTER triggers it can provide a noticeable performance improvement, since queuing of a deferred trigger event and re-fetching of the row(s) at end of statement can be short-circuited if the trigger does not need to be fired. Takahiro Itagaki, reviewed by KaiGai Kohei.
2009-10-27Fix AfterTriggerSaveEvent to use a test and elog, not just Assert, to checkTom Lane
that it's called within an AfterTriggerBeginQuery/AfterTriggerEndQuery pair. The RI cascade triggers suppress that overhead on the assumption that they are always run non-deferred, so it's possible to violate the condition if someone mistakenly changes pg_trigger to mark such a trigger deferred. We don't really care about supporting that, but throwing an error instead of crashing seems desirable. Per report from Marcelo Costa.
2009-10-26Re-implement EvalPlanQual processing to improve its performance and eliminateTom Lane
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.
2009-10-14Support SQL-compliant triggers on columns, ie fire only if certain columnsTom Lane
are named in the UPDATE's SET list. Note: the schema of pg_trigger has not actually changed; we've just started to use a column that was there all along. catversion bumped anyway so that this commit is included in the history of potentially interesting changes to system catalog contents. Itagaki Takahiro