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* Consider index-only scans even when there is no matching qual or ORDER BY.Tom Lane2011-10-11
| | | | By popular demand.
* Rearrange the implementation of index-only scans.Tom Lane2011-10-11
| | | | | | | | | | | | | | | | | | | | | | 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).
* Replace hardcoded switch in object_exists() with a lookup table.Robert Haas2011-10-11
| | | | | | | | | | | | There's no particular advantage to this change on its face; indeed, it's possible that this might be slightly slower than the old way. But it makes this information more easily accessible to other functions, and therefore paves the way for future code consolidation. Performance isn't critical here, so there's no need to be smart about how we do the search. This is a heavily cut-down version of a patch from KaiGai Kohei, with several fixes by me. Additional review from Dimitri Fontaine.
* Repair breakage in VirtualXactLock.Robert Haas2011-10-11
| | | | | I broke this in commit 84e37126770dd6de903dad88ce150a49b63b5ef9. Report and fix by Fujii Masao.
* Mark GUC external_pid_file's default as '' in postgresql.conf, ratherBruce Momjian2011-10-10
| | | | than '(none)'.
* Fix ALTER TABLE ONLY .. DROP CONSTRAINT.Robert Haas2011-10-09
| | | | | | | | | | | | | | | | | | When I consolidated two copies of the HOT-chain search logic in commit 4da99ea4231e3d8bbf28b666748c1028e7b7d665, I introduced a behavior change: the old code wouldn't necessarily traverse the entire chain, if the most recently returned tuple were updated while the HOT chain traversal is in progress. The new behavior seems more correct, but unfortunately, the code here relies on a scan with SnapshotNow failing to see its own updates. That seems pretty shaky even with the old HOT chain traversal behavior, since there's no guarantee that these updates will always be HOT, but it's trivial to broke a failure with the new HOT search logic. Fix by updating just the first matching pg_constraint tuple, rather than all of them, since there should be only one anyway. But since nobody has reproduced this failure on older versions, no back-patch for now. Report and test case by Alex Hunsaker; tablecmds.c changes by me.
* Clean up a couple of box gist helper functions.Heikki Linnakangas2011-10-09
| | | | | | | | | | The original idea of this patch was to make box picksplit run faster, by eliminating unnecessary palloc() overhead, but that was obsoleted by the new double-sorting split algorithm that doesn't call these functions so heavily anymore. Nevertheless, the code looks better this way. Original patch by me, reviewed and tidied up after the double-sorting patch by Kevin Grittner.
* Improve index-only scans to avoid repeated access to the index page.Tom Lane2011-10-09
| | | | | | | | | | | | We copy all the matched tuples off the page during _bt_readpage, instead of expensively re-locking the page during each subsequent tuple fetch. This costs a bit more local storage, but not more than 2*BLCKSZ worth, and the reduction in LWLock traffic is certainly worth that. What's more, this lets us get rid of the API wart in the original patch that said an index AM could randomly decline to supply an index tuple despite having asserted pg_am.amcanreturn. That will be important for future improvements in the index-only-scan feature, since the executor will now be able to rely on having the index data available.
* Fix brain fade in cost estimation for index-only scans.Tom Lane2011-10-08
| | | | | visibility_fraction should not be applied to regular indexscans. Noted by Cédric Villemain.
* Don't let transform_null_equals=on affect CASE foo WHEN NULL ... constructs.Heikki Linnakangas2011-10-08
| | | | | | | | | transform_null_equals is only supposed to affect "foo = NULL" expressions given directly by the user, not the internal "foo = NULL" expression generated from CASE-WHEN. This fixes bug #6242, reported by Sergey. Backpatch to all supported branches.
* Support index-only scans using the visibility map to avoid heap fetches.Tom Lane2011-10-07
| | | | | | | | | | | | | 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.
* Ensure walsenders can be SIGTERMed while in non-walsender codeMagnus Hagander2011-10-06
| | | | | | | In oder to exit on SIGTERM when in non-walsender code, such as do_pg_stop_backup(), we need to set the interrupt variables that are used there, and not just the walsender local ones.
* Add postmaster -C option to query configuration parameters, and haveBruce Momjian2011-10-06
| | | | | | pg_ctl use that to query the data directory for config-only installs. This fixes awkward or impossible pg_ctl operation for config-only installs.
* Replace the "New Linear" GiST split algorithm for boxes and points with aHeikki Linnakangas2011-10-06
| | | | | | | new double-sorting algorithm. The new algorithm produces better quality trees, making searches faster. Alexander Korotkov
* Improve and simplify CREATE EXTENSION's management of GUC variables.Tom Lane2011-10-05
| | | | | | | | | | | | | | | | | | | | | CREATE EXTENSION needs to transiently set search_path, as well as client_min_messages and log_min_messages. We were doing this by the expedient of saving the current string value of each variable, doing a SET LOCAL, and then doing another SET LOCAL with the previous value at the end of the command. This is a bit expensive though, and it also fails badly if there is anything funny about the existing search_path value, as seen in a recent report from Roger Niederland. Fortunately, there's a much better way, which is to piggyback on the GUC infrastructure previously developed for functions with SET options. We just open a new GUC nesting level, do our assignments with GUC_ACTION_SAVE, and then close the nesting level when done. This automatically restores the prior settings without a re-parsing pass, so (in principle anyway) there can't be an error. And guc.c still takes care of cleanup in event of an error abort. The CREATE EXTENSION code for this was modeled on some much older code in ri_triggers.c, which I also changed to use the better method, even though there wasn't really much risk of failure there. Also improve the comments in guc.c to reflect this additional usage.
* Improve define_custom_variable's handling of pre-existing settings.Tom Lane2011-10-04
| | | | | | | | | | | | | | | | Arrange for any problems with pre-existing settings to be reported as WARNING not ERROR, so that we don't undesirably abort the loading of the incoming add-on module. The bad setting is just discarded, as though it had never been applied at all. (This requires a change in the API of set_config_option. After some thought I decided the most potentially useful addition was to allow callers to just pass in a desired elevel.) Arrange to restore the complete stacked state of the variable, rather than cheesily reinstalling only the active value. This ensures that custom GUCs will behave unsurprisingly even when the module loading operation occurs within nested subtransactions that have changed the active value. Since a module load could occur as a result of, eg, a PL function call, this is not an unlikely scenario.
* Fix uninitialized-variable bug.Tom Lane2011-10-04
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* Add sourcefile/sourceline data to EXEC_BACKEND GUC transmission files.Tom Lane2011-10-04
| | | | | | | | | | This oversight meant that on Windows, the pg_settings view would not display source file or line number information for values coming from postgresql.conf, unless the backend had received a SIGHUP since starting. In passing, also make the error detection in read_nondefault_variables a tad more thorough, and fix it to not lose precision on float GUCs (these changes are already in HEAD as of my previous commit).
* Remember the source GucContext for each GUC parameter.Tom Lane2011-10-04
| | | | | | | | | | | | We used to just remember the GucSource, but saving GucContext too provides a little more information --- notably, whether a SET was done by a superuser or regular user. This allows us to rip out the fairly dodgy code that define_custom_variable used to use to try to infer the context to re-install a pre-existing setting with. In particular, it now works for a superuser to SET a extension's SUSET custom variable before loading the associated extension, because GUC can remember whether the SET was done as a superuser or not. The plperl regression tests contain an example where this is useful.
* Use callbacks in SlruScanDirectory for the actual actionAlvaro Herrera2011-10-04
| | | | | | | | | | | | Previously, the code assumed that the only possible action to take was to delete files behind a certain cutoff point. The async notify code was already a crock: it used a different "pagePrecedes" function for truncation than for regular operation. By allowing it to pass a callback to SlruScanDirectory it can do cleanly exactly what it needs to do. The clog.c code also had its own use for SlruScanDirectory, which is made a bit simpler with this.
* Remove the custom_variable_classes parameter.Tom Lane2011-10-04
| | | | | | | | | | | | | | | | | This variable provides only marginal error-prevention capability (since it can only check the prefix of a qualified GUC name), and the consensus is that that isn't worth the amount of hassle that maintaining the setting creates for DBAs. So, let's just remove it. With this commit, the system will silently accept a value for any qualified GUC name at all, whether it has anything to do with any known extension or not. (Unqualified names still have to match known built-in settings, though; and you will get a WARNING at extension load time if there's an unrecognized setting with that extension's prefix.) There's still some discussion ongoing about whether to tighten that up and if so how; but if we do come up with a solution, it's not likely to look anything like custom_variable_classes.
* ProcedureCreate neglected to record dependencies on default expressions.Tom Lane2011-10-03
| | | | | | | Thus, an object referenced in a default expression could be dropped while the function remained present. This was unaccountably missed in the original patch to add default parameters for functions. Reported by Pavel Stehule.
* Restructure error handling in reading of postgresql.conf.Tom Lane2011-10-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch has two distinct purposes: to report multiple problems in postgresql.conf rather than always bailing out after the first one, and to change the policy for whether changes are applied when there are unrelated errors in postgresql.conf. Formerly the policy was to apply no changes if any errors could be detected, but that had a significant consistency problem, because in some cases specific values might be seen as valid by some processes but invalid by others. This meant that the latter processes would fail to adopt changes in other parameters even though the former processes had done so. The new policy is that during SIGHUP, the file is rejected as a whole if there are any errors in the "name = value" syntax, or if any lines attempt to set nonexistent built-in parameters, or if any lines attempt to set custom parameters whose prefix is not listed in (the new value of) custom_variable_classes. These tests should always give the same results in all processes, and provide what seems a reasonably robust defense against loading values from badly corrupted config files. If these tests pass, all processes will apply all settings that they individually see as good, ignoring (but logging) any they don't. In addition, the postmaster does not abandon reading a configuration file after the first syntax error, but continues to read the file and report syntax errors (up to a maximum of 100 syntax errors per file). The postmaster will still refuse to start up if the configuration file contains any errors at startup time, but these changes allow multiple errors to be detected and reported before quitting. Alexey Klyukin, reviewed by Andy Colson and av (Alexander ?) with some additional hacking by Tom Lane
* Improve generated column names for cases involving sub-SELECTs.Tom Lane2011-10-01
| | | | | | | | We'll now use "exists" for EXISTS(SELECT ...), "array" for ARRAY(SELECT ...), or the sub-select's own result column name for a simple expression sub-select. Previously, you usually got "?column?" in such cases. Marti Raudsepp, reviewed by Kyotaro Horiugchi
* Support GiST index support functions that want to cache data across calls.Tom Lane2011-09-30
| | | | | | | | | | | | pg_trgm was already doing this unofficially, but the implementation hadn't been thought through very well and leaked memory. Restructure the core GiST code so that it actually works, and document it. Ordinarily this would have required an extra memory context creation/destruction for each GiST index search, but I was able to avoid that in the normal case of a non-rescanned search by finessing the handling of the RBTree. It used to have its own context always, but now shares a context with the scan-lifespan data structures, unless there is more than one rescan call. This should make the added overhead unnoticeable in typical cases.
* Fix recursion into previously planned sub-query in examine_simple_variable.Tom Lane2011-09-29
| | | | | | | | This code was looking at the sub-Query tree as seen in the parent query's RangeTblEntry; but that's the pristine parser output, and what we need to look at is the tree as it stands at the completion of planning. Otherwise we might pick up a Var that references a subquery that got flattened and hence has no RelOptInfo in the subroot. Per report from Peter Geoghegan.
* Fix pg_upgrade for EXEC_BACKEND builds (e.g. Windows) by properlyBruce Momjian2011-09-29
| | | | | | passing the -b/binary-upgrade flag. Backpatch to 9.1.X.
* Fix index matching for operators with mixed collatable/noncollatable inputs.Tom Lane2011-09-29
| | | | | | | | | | | | | | | | | If an indexable operator for a non-collatable indexed datatype has a collatable right-hand input type, any OpExpr for it will be marked with a nonzero inputcollid (since having one collatable input is sufficient to make that happen). However, an index on a non-collatable column certainly doesn't have any collation. This caused us to fail to match such operators to their indexes, because indxpath.c required an exact match of index collation and clause collation. It seems correct to allow a match when the index is collation-less regardless of the clause's inputcollid: an operator with both noncollatable and collatable inputs could perhaps depend on the collation of the collatable input, but it could hardly expect the index for the noncollatable input to have that same collation. Per bug #6232 from Pierre Ducroquet. His example is specifically about "hstore ? text" but the problem seems quite generic.
* Update comments related to the crash-safety of the visibility map.Robert Haas2011-09-27
| | | | | | | | In hio.c, document how we avoid deadlock with respect to visibility map buffer locks. In visibilitymap.c, update the LOCKING section of the file header comment. Both oversights noted by Heikki Linnakangas.
* heap_update() must recheck tuple after unlocking and relocking buffer.Robert Haas2011-09-27
| | | | | Bug found by Alvaro Herrera, fix suggested by Heikki Linnakangas and reviewed by Tom Lane.
* Fix window functions that sort by expressions involving aggregates.Tom Lane2011-09-26
| | | | | | | | | | | | | | | | | | | | | | | In commit c1d9579dd8bf3c921ca6bc2b62c40da6d25372e5, I changed things so that the output of the Agg node that feeds the window functions would not list any ungrouped Vars directly. Formerly, for example, the Agg tlist might have included both "x" and "sum(x)", which is not really valid if "x" isn't a grouping column. If we then had a window function ordering on something like "sum(x) + 1", prepare_sort_from_pathkeys would find no exact match for this in the Agg tlist, and would conclude that it must recompute the expression. But it would break the expression down to just the Var "x", which it would find in the tlist, and then rebuild the ORDER BY expression using a reference to the subplan's "x" output. Now, after the above-referenced changes, "x" isn't in the Agg tlist if it's not a grouping column, so that prepare_sort_from_pathkeys fails with "could not find pathkey item to sort", as reported by Bricklen Anderson. The fix is to not break down Aggrefs into their component parts, but just treat them as irreducible expressions to be sought in the subplan tlist. This is definitely OK for the use with respect to window functions in grouping_planner, since it just built the tlist being used on the same basis. AFAICT it is safe for other uses too; most of the other call sites couldn't encounter Aggrefs anyway.
* Allow snapshot references to still work during transaction abort.Tom Lane2011-09-26
| | | | | | | | | | | | | | | | | | | | | | | | In REPEATABLE READ (nee SERIALIZABLE) mode, an attempt to do GetTransactionSnapshot() between AbortTransaction and CleanupTransaction failed, because GetTransactionSnapshot would recompute the transaction snapshot (which is already wrong, given the isolation mode) and then re-register it in the TopTransactionResourceOwner, leading to an Assert because the TopTransactionResourceOwner should be empty of resources after AbortTransaction. This is the root cause of bug #6218 from Yamamoto Takashi. While changing plancache.c to avoid requesting a snapshot when handling a ROLLBACK masks the problem, I think this is really a snapmgr.c bug: it's lower-level than the resource manager mechanism and should not be shutting itself down before we unwind resource manager resources. However, just postponing the release of the transaction snapshot until cleanup time didn't work because of the circular dependency with TopTransactionResourceOwner. Fix by managing the internal reference to that snapshot manually instead of depending on TopTransactionResourceOwner. This saves a few cycles as well as making the module layering more straightforward. predicate.c's dependencies on TopTransactionResourceOwner go away too. I think this is a longstanding bug, but there's no evidence that it's more than a latent bug, so it doesn't seem worth any risk of back-patching.
* Update obsolete comments.Robert Haas2011-09-26
| | | | | | | This was partially fixed by 57fdb2b0d835fe201434fc28bf5dabf83ada26d1, back in 2005, but it missed a couple of spots. YAMAMOTO Takashi
* Use a fresh copy of query_list when making a second plan in GetCachedPlan.Tom Lane2011-09-26
| | | | | | | | The code path that tried a generic plan, didn't like it, and then made a custom plan was mistakenly passing the same copy of the query_list to the planner both times. This doesn't work too well for nontrivial queries, since the planner tends to scribble on its input. Diagnosis and fix by Yamamoto Takashi.
* Avoid unnecessary snapshot-acquisitions in BuildCachedPlan.Tom Lane2011-09-25
| | | | | | | | | | | | | I had copied-and-pasted a claim that we couldn't reach this point when dealing with utility statements, but that was a leftover from when the caller was required to supply a plan to start with. We now will go through here at least once when handling a utility statement, so it seems worth a check to see whether a snapshot is actually needed. (Note that analyze_requires_snapshot is quite a cheap test.) Per suggestion from Yamamoto Takashi. I don't think I believe that this resolves his reported assertion failure; but it's worth changing anyway, just to save a cycle or two.
* Recognize self-contradictory restriction clauses for non-table relations.Tom Lane2011-09-24
| | | | | | | | | | | | | | | | | | The constraint exclusion feature checks for contradictions among scan restriction clauses, as well as contradictions between those clauses and a table's CHECK constraints. The first aspect of this testing can be useful for non-table relations (such as subqueries or functions-in-FROM), but the feature was coded with only the CHECK case in mind so we were applying it only to plain-table RTEs. Move the relation_excluded_by_constraints call so that it is applied to all RTEs not just plain tables. With the default setting of constraint_exclusion this results in no extra work, but with constraint_exclusion = ON we will detect optimizations that we missed before (at the cost of more planner cycles than we expended before). Per a gripe from Gunnlaugur Þór Briem. Experimentation with his example also showed we were not being very bright about the case where constraint exclusion is proven within a subquery within UNION ALL, so tweak the code to allow set_append_rel_pathlist to recognize such cases.
* Memory barrier support for PostgreSQL.Robert Haas2011-09-23
| | | | | | | This is not actually used anywhere yet, but it gets the basic infrastructure in place. It is fairly likely that there are bugs, and support for some important platforms may be missing, so we'll need to refine this as we go along.
* Make EXPLAIN ANALYZE report the numbers of rows rejected by filter steps.Tom Lane2011-09-22
| | | | | | | | | | | | | | | 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
* Fix another bit of unlogged-table-induced breakage.Robert Haas2011-09-21
| | | | | | | | Per bug #6205, reported by Abel Abraham Camarillo Ojeda. This isn't a particularly elegant fix, but I'm trying to minimize the chances of causing yet another round of breakage. Adjust regression tests to exercise this case.
* Suppress "unused function" warning when not HAVE_LOCALE_T.Tom Lane2011-09-20
| | | | Forgot to consider this case ...
* Improve reporting of newlocale() failures in CREATE COLLATION.Tom Lane2011-09-20
| | | | | | | | | | The standardized errno code for "no such locale" failures is ENOENT, which we were just reporting at face value, viz "No such file or directory". Per gripe from Thom Brown, this might confuse users, so add an errdetail message to clarify what it means. Also, report newlocale() failures as ERRCODE_INVALID_PARAMETER_VALUE rather than using errcode_for_file_access(), since newlocale()'s errno values aren't necessarily tied directly to file access failures.
* Fix Assert failure in new plancache code.Tom Lane2011-09-17
| | | | | | | | | | | | | | The regression tests were failing with CLOBBER_CACHE_ALWAYS enabled, as reported by buildfarm member jaguar. There was an Assert in BuildCachedPlan that asserted that the CachedPlanSource hadn't been invalidated since we called RevalidateCachedQuery, which in theory can't happen because we are holding locks on all the relevant database objects. However, CLOBBER_CACHE_ALWAYS generates a false positive by making an invalidation happen anyway; and on reflection, that could also occur as a result of a badly-timed sinval reset due to queue overflow. We could just remove the Assert and forge ahead with the not-really-stale querytree, but it seems safer to do another RevalidateCachedQuery call just to make real sure everything's OK.
* Remove debug logging for pgstat wait timeout.Tom Lane2011-09-16
| | | | | | | | | | | | | | | This reverts commit 79b2ee20c8a041a85dd230c4e787bef22edae57b, which proved to not be very informative; it looks like the "pgstat wait timeout" warnings in the buildfarm are just a symptom of running on heavily loaded machines, and there isn't any weird mechanism causing them to appear. To try to reduce the frequency of buildfarm failures from this effect, increase PGSTAT_MAX_WAIT_TIME from 5 seconds to 10. Also, arrange to not send a fresh inquiry message every single time through the loop, as that seems more likely to cause problems (by swamping the collector) than fix them. We'll now send an inquiry the first time through the delay loop, and every 640 msec thereafter.
* Avoid unnecessary page-level SSI lock check in heap_insert().Tom Lane2011-09-16
| | | | | | | | | | As observed by Heikki, we need not conflict on heap page locks during an insert; heap page locks are only aggregated tuple locks, they don't imply locking "gaps" as index page locks do. So we can avoid some unnecessary conflicts, and also do the SSI check while not holding exclusive lock on the target buffer. Kevin Grittner, reviewed by Jeff Davis. Back-patch to 9.1.
* gistendscan() forgot to free so->giststate.Tom Lane2011-09-16
| | | | | | | | | | This oversight led to a massive memory leak --- upwards of 10KB per tuple --- during creation-time verification of an exclusion constraint based on a GIST index. In most other scenarios it'd just be a leak of 10KB that would be recovered at end of query, so not too significant; though perhaps the leak would be noticeable in a situation where a GIST index was being used in a nestloop inner indexscan. In any case, it's a real leak of long standing, so patch all supported branches. Per report from Harald Fuchs.
* Redesign the plancache mechanism for more flexibility and efficiency.Tom Lane2011-09-16
| | | | | | | | | | | | | | | | | | | Rewrite plancache.c so that a "cached plan" (which is rather a misnomer at this point) can support generation of custom, parameter-value-dependent plans, and can make an intelligent choice between using custom plans and the traditional generic-plan approach. The specific choice algorithm implemented here can probably be improved in future, but this commit is all about getting the mechanism in place, not the policy. In addition, restructure the API to greatly reduce the amount of extraneous data copying needed. The main compromise needed to make that possible was to split the initial creation of a CachedPlanSource into two steps. It's worth noting in particular that SPI_saveplan is now deprecated in favor of SPI_keepplan, which accomplishes the same end result with zero data copying, and no need to then spend even more cycles throwing away the original SPIPlan. The risk of long-term memory leaks while manipulating SPIPlans has also been greatly reduced. Most of this improvement is based on use of the recently-added MemoryContextSetParent primitive.
* Split walsender.h in public/private headersAlvaro Herrera2011-09-13
| | | | | This dramatically cuts short the number of headers the public one brings into whatever includes it.
* deflist_to_tuplestore dumped core on an option with no value.Tom Lane2011-09-13
| | | | | | | Make it return NULL for the option_value, instead. Per report from Frank van Vugt. Back-patch to 8.4 where this code was added.
* In the final emptying phase of the new GiST buffering build, set theHeikki Linnakangas2011-09-12
| | | | | | | | | | queuedForEmptying flag correctly on buffer when adding it to the queue. Also, don't add buffer to the queue if it's there already. These were harmless oversights; failing to set the flag just means that a buffer might get added to the queue twice if more tuples are added to it (although that can't actually happen at this point because all the upper buffers have already been emptied), and having the same buffer twice in the emptying queue is harmless. But better be tidy.
* Invent a new memory context primitive, MemoryContextSetParent.Tom Lane2011-09-11
| | | | | | | This function will be useful for altering the lifespan of a context after creation (for example, by creating it under a transient context and later reparenting it to belong to a long-lived context). It costs almost no new code, since we can refactor what was there. Per my proposal of yesterday.