will be released by transaction abort before _bt_end_vacuum gets called.
If either of these "can't happen" errors actually happened, we'd freeze up
trying to acquire an already-held lock. Latest word is that this does
not explain Martin Pitt's trouble report, but it still looks like a bug.
executed in read_only mode. This could lead to various relatively-subtle
failures, such as an allegedly stable function returning non-stable results.
Bug goes all the way back to the introduction of read-only mode in 8.0.
Per report from Gaetano Mendola.
did not expect that a DEAD tuple could follow a RECENTLY_DEAD tuple in an
update chain, but because the OldestXmin rule for determining deadness is a
simplification of reality, it is possible for this situation to occur
(implying that the RECENTLY_DEAD tuple is in fact dead to all observers,
but this patch does not attempt to exploit that). The code would follow a
chain forward all the way, but then stop before a DEAD tuple when backing
up, meaning that not all of the chain got moved. This could lead to copying
the chain multiple times (resulting in duplicate copies of the live tuple at
its end), or leaving dangling index entries behind (which, aside from
generating warnings from later vacuums, creates a risk of wrong query
results or bogus duplicate-key errors once the heap slot the index entry
points to is repopulated).
The fix is to recheck HeapTupleSatisfiesVacuum while following a chain
forward, and to stop if a DEAD tuple is reached. Each contiguous group
of RECENTLY_DEAD tuples will therefore be copied as a separate chain.
The patch also adds a couple of extra sanity checks to verify correct
behavior.
Per report and test case from Pavan Deolasee.
POSIX-style timezone specs that don't exactly match any database entry will
be treated as having correct USA DST rules. Also, document that this can
be changed if you want to use some other DST rules with a POSIX zone spec.
We could consider changing localtime.c's TZDEFRULESTRING, but since that
facility can only deal with one DST transition rule, it seems fairly useless
now; might as well just plan to override it using a "posixrules" entry.
Backpatch as far as 8.0. There isn't much we can do in 7.x ... either your
libc gets it right, or it doesn't.
even if none of the fields in the pg_class row change. This behavior is
necessary to ensure other backends flush rd_targblock values that might
point to truncated-away pages. We got this right pre-8.2 but it was broken
by overoptimistic change to not write out the pg_class row if unchanged.
Per report from Pavan Deolasee.
fix it. Add macroses DatumGetNDBOX, PG_GETARG_NDBOX and PG_RETURN_NDBOX.
Backpatch for 8.2 too.
Previous versions use version 0 calling conventions. And fmgr code detoast
values for user-defined functions.
check_sql_fn_retval allows binary-compatibility cases, the expression
extracted from an inline-able SQL function might have a type that is only
binary-compatible with the declared function result type. To avoid possibly
changing the semantics of the expression, we should insert a RelabelType node
in such cases. This has only been shown to have bad consequences in recent
8.1 and up releases, but I suspect there may be failure cases in the older
branches too, so patch it all the way back. Per bug #3116 from Greg Mullane.
Along the way, fix an omission in eval_const_expressions_mutator: it failed
to copy the relabelformat field when processing a RelabelType. No known
observable failures from this, but it definitely isn't intended behavior.
portals using PORTAL_UTIL_SELECT strategy. This is currently significant only
for FETCH queries, which are supposed to include a count in the tag. Seems
it's been broken since 7.4, but nobody noticed before Knut Lehre.
JOIN quals, just like WHERE quals, even if they reference every one of the
join's relations. Now that we can reorder outer and inner joins, it's
possible for such a qual to end up being assigned to an outer join plan node,
and we mustn't have it treated as a join qual rather than a filter qual for
the node. (If it were, the join could produce null-extended rows that it
shouldn't.) Per bug report from Pelle Johansson.
be checked at plan levels below the top; namely, we have to allow for Result
nodes inserted just above a nestloop inner indexscan. Should think about
using the general Param mechanism to pass down outer-relation variables, but
for the moment we need a back-patchable solution. Per report from Phil Frost.
considered when it is necessary to do so because of a join-order restriction
(that is, an outer-join or IN-subselect construct). The former coding was a
bit ad-hoc and inconsistent, and it missed some cases, as exposed by Mario
Weilguni's recent bug report. His specific problem was that an IN could be
turned into a "clauseless" join due to constant-propagation removing the IN's
joinclause, and if the IN's subselect involved more than one relation and
there was more than one such IN linking to the same upper relation, then the
only valid join orders involve "bushy" plans but we would fail to consider the
specific paths needed to get there. (See the example case added to the join
regression test.) On examining the code I wonder if there weren't some other
problem cases too; in particular it seems that GEQO was defending against a
different set of corner cases than the main planner was. There was also an
efficiency problem, in that when we did realize we needed a clauseless join
because of an IN, we'd consider clauseless joins against every other relation
whether this was sensible or not. It seems a better design is to use the
outer-join and in-clause lists as a backup heuristic, just as the rule of
joining only where there are joinclauses is a heuristic: we'll join two
relations if they have a usable joinclause *or* this might be necessary to
satisfy an outer-join or IN-clause join order restriction. I refactored the
code to have just one place considering this instead of three, and made sure
that it covered all the cases that any of them had been considering.
Backpatch as far as 8.1 (which has only the IN-clause form of the disease).
By rights 8.0 and 7.4 should have the bug too, but they accidentally fail
to fail, because the joininfo structure used in those releases preserves some
memory of there having once been a joinclause between the inner and outer
sides of an IN, and so it leads the code in the right direction anyway.
I'll be conservative and not touch them.
WHERE clauses. createplan.c is now willing to stick a gating Result node
almost anywhere in the plan tree, and in particular one can wind up directly
underneath a MergeJoin node. This means it had better be willing to handle
Mark/Restore. Fortunately, that's trivial in such cases, since we can just
pass off the call to the input node (which the planner has previously ensured
can handle Mark/Restore). Per report from Phil Frost.
that overlap an outer join's min_righthand but aren't fully contained in it,
to support joining within the RHS after having performed an outer join that
can commute with this one. Aside from the direct fix in make_join_rel(),
fix has_join_restriction() and GEQO's desirable_join() to consider this
possibility. Per report from Ian Harding.
get away with not (re)initializing a local variable if the variable is marked
"isconst" and not "isnull". Unfortunately it makes this decision after having
already freed the old value, meaning that something like
for i in 1..10 loop
declare c constant text := 'hi there';
leads to subsequent accesses to freed memory, and hence probably crashes.
(In particular, this is why Asif Ali Rehman's bug leads to crash and not
just an unexpectedly-NULL value for SQLERRM: SQLERRM is marked CONSTANT
and so triggers this error.)
The whole thing seems wrong on its face anyway: CONSTANT means that you can't
change the variable inside the block, not that the initializer expression is
guaranteed not to change value across successive block entries. Hence,
remove the "optimization" instead of trying to fix it.
DECLARE section needs to know about it. Formerly, everyplace besides DECLARE
that created variables needed to do "plpgsql_add_initdatums(NULL)" to prevent
those variables from being sucked up as part of a subsequent DECLARE block.
This is obviously error-prone, and in fact the SQLSTATE/SQLERRM patch had
failed to do it for those two variables, leading to the bug recently exhibited
by Asif Ali Rehman: a DECLARE within an exception handler tried to reinitialize
SQLERRM.
Although the SQLSTATE/SQLERRM patch isn't in any pre-8.1 branches, and so
I can't point to a demonstrable failure there, it seems wise to back-patch
this into the older branches anyway, just to keep the logic similar to HEAD.
