tests into a small common subroutine, and eliminate an unnecessary difference
in the order in which conditions are tested. Per a comment from Robert Haas.
is unique and is not referenced above the join. In this case the inner
side doesn't affect the query result and can be thrown away entirely.
Although perhaps nobody would ever write such a thing by hand, it's
a reasonably common case in machine-generated SQL.
The current implementation only recognizes the case where the inner side
is a simple relation with a unique index matching the query conditions.
This is enough for the use-cases that have been shown so far, but we
might want to try to handle other cases later.
Robert Haas, somewhat rewritten by Tom
In practice these mistakes were always masked when full_page_writes was on,
because XLogInsert would always choose to log the full page, and then
ginRedoInsertListPage wouldn't try to do anything. But with full_page_writes
off a WAL replay failure was certain.
The GIN_INSERT_LISTPAGE record type could probably be eliminated entirely
in favor of using XLOG_HEAP_NEWPAGE, but I refrained from doing that now
since it would have required a significantly more invasive patch.
In passing do a little bit of code cleanup, including making the accounting
for free space on GIN list pages more precise. (This wasn't a bug as the
errors were always in the conservative direction.)
Per report from Simon. Back-patch to 8.4 which contains the identical code.
if salt_len == 0. This seems to be mostly academic, since nearly all calling
code paths guarantee nonempty salt; the only case that doesn't is
PQencryptPassword where the caller could mistakenly pass an empty username.
So, fix it but don't bother backpatching. Per ljb.
of checkpoint. Although the checkpoint has been written to WAL at that point
already, so that all data is safe, and we'll retry removing the WAL segment at
the next checkpoint, if such a failure persists we won't be able to remove any
other old WAL segments either and will eventually run out of disk space. It's
better to treat the failure as non-fatal, and move on to clean any other WAL
segment and continue with any other end-of-checkpoint cleanup.
We don't normally expect any such failures, but on Windows it can happen with
some anti-virus or backup software that lock files without FILE_SHARE_DELETE
flag.
Also, the loop in pgrename() to retry when the file is locked was broken. If a
file is locked on Windows, you get ERROR_SHARE_VIOLATION, not
ERROR_ACCESS_DENIED, at least on modern versions. Fix that, although I left
the check for ERROR_ACCESS_DENIED in there as well (presumably it was correct
in some environment), and added ERROR_LOCK_VIOLATION to be consistent with
similar checks in pgwin32_open(). Reduce the timeout on the loop from 30s to
10s, on the grounds that since it's been broken, we've effectively had a
timeout of 0s and no-one has complained, so a smaller timeout is actually
closer to the old behavior. A longer timeout would mean that if recycling a
WAL file fails because it's locked for some reason, InstallXLogFileSegment()
will hold ControlFileLock for longer, potentially blocking other backends, so
a long timeout isn't totally harmless.
While we're at it, set errno correctly in pgrename().
Backpatch to 8.2, which is the oldest version supported on Windows. The xlog.c
changes would make sense on other platforms and thus on older versions as
well, but since there's no such locking issues on other platforms, it's not
worth it.
an explicit model of rescan costs being different from first-time costs.
The costing of Material nodes in particular now has some visible relationship
to the actual runtime behavior, where before it was essentially fantasy.
This also fixes up a couple of places where different materialized plan types
were treated differently for no very good reason (probably just oversights).
A couple of the regression tests are affected, because the planner now chooses
to put the other relation on the inside of a nestloop-with-materialize.
So far as I can see both changes are sane, and the planner is now more
consistently following the expectation that it should prefer to materialize
the smaller of two relations.
Per a recent discussion with Robert Haas.
If Apple doesn't fix that reasonably soon, we'll have to consider
back-patching a workaround; but for now, just hack it in HEAD so that
we can get buildfarm reports on HEAD from OS X machines.
Per Jan Otto.
In this case we generate two PathKey references to the expression (one for
DISTINCT and one for ORDER BY) and they really need to refer to the same
EquivalenceClass. However get_eclass_for_sort_expr was being overly paranoid
and creating two different EC's. Correct behavior is to use the SortGroupRef
index to decide whether two references to volatile expressions that are
equal() (ie textually equivalent) should be considered the same.
Backpatch to 8.4. Possibly this should be changed in 8.3 as well, but
I'll refrain in the absence of evidence of a visible failure in that branch.
Per bug #5049.
use that value when the backend is new enough to allow it. This responds
to bug report from Keh-Cheng Chu pointing out that although 2 extra digits
should be sufficient to dump and restore float8 exactly, it is possible to
need 3 extra digits for float4 values.
file handle on it, the file goes into "pending deletion" state where it
still shows up in directory listing, but isn't accessible otherwise. That
confuses RemoveOldXLogFiles(), making it think that the file hasn't been
archived yet, while it actually was, and it was deleted along with the .done
file.
Fix that by renaming the file with ".deleted" extension before deleting it.
Also check the return value of rename() and unlink(), so that if the removal
fails for any reason (e.g another process is holding the file locked), we
don't delete the .done file until the WAL file is really gone.
Backpatch to 8.2, which is the oldest version supported on Windows.
Before, PL/Python converted data between SQL and Python by going
through a C string representation. This broke for bytea in two ways:
- On input (function parameters), you would get a Python string that
contains bytea's particular external representation with backslashes
etc., instead of a sequence of bytes, which is what you would expect
in a Python environment. This problem is exacerbated by the new
bytea output format.
- On output (function return value), null bytes in the Python string
would cause truncation before the data gets stored into a bytea
datum.
This is now fixed by converting directly between the PostgreSQL datum
and the Python representation.
The required generalized infrastructure also allows for other
improvements in passing:
- When returning a boolean value, the SQL datum is now true if and
only if Python considers the value that was passed out of the
PL/Python function to be true. Previously, this determination was
left to the boolean data type input function. So, now returning
'foo' results in true, because Python considers it true, rather than
false because PostgreSQL considers it false.
- On input, we can convert the integer and float types directly to
their Python equivalents without having to go through an
intermediate string representation.
original patch by Caleb Welton, with updates by myself
code was already okay with this, but the hack that obtained the output
column types of a recursive union in advance of doing real parse analysis
of the recursive union forgot to handle the case where there was an inner
WITH clause available to the non-recursive term. Best fix seems to be to
refactor so that we don't need the "throwaway" parse analysis step at all.
Instead, teach the transformSetOperationStmt code to set up the CTE's output
column information after it's processed the non-recursive term normally.
Per report from David Fetter.
build actually attempts to advertise itself via Bonjour. Formerly it always
did so, which meant that packagers had to decide for their users whether
this behavior was wanted or not. The default is "off" to be on the safe
side, though this represents a change in the default behavior of a
Bonjour-enabled build. Per discussion.
with the not-so-deprecated DNSServiceRegister. This patch shouldn't change
any user-visible behavior, it just gets rid of a deprecation warning in
--with-bonjour builds. The new code will fail on OS X releases before 10.3,
but it seems unlikely that anyone will want to run Postgres 8.5 on 10.2.
Formerly, these message types would be discarded unless there was already
a stats hash table entry for the target table. However, the intent of
saving hash table space for unused tables was subverted by the fact that
the physical I/O done by the vacuum or analyze would result in an immediately
following tabstat message, which would create the hash table entry anyway.
All that we had left was surprising loss of statistical data, as in a recent
complaint from Jaime Casanova.
It seems unlikely that a real database would have many tables that go totally
untouched over the long haul, so the consensus is that this "optimization"
serves little purpose anyhow. Remove it, and just create the hash table
entry on demand in all cases.
input functions don't accept either. While the backend can handle such
values fine, they can cause trouble in clients and in pg_dump/restore.
This is followup to the original issue on time datatype reported by Andrew
McNamara a while ago. Like that one, none of these seem worth
back-patching.
specify an encoding explicitly, we used to treat it as being in database
encoding when we parsed it, but then perform a UTF-8 -> database encoding
conversion on it, which was completely bogus. It's now consistently treated as
UTF-8.
to unload and re-load the library.
The difficulty with unloading a library is that we haven't defined safe
protocols for doing so. In particular, there's no safe mechanism for
getting out of a "hook" function pointer unless libraries are unloaded
in reverse order of loading. And there's no mechanism at all for undefining
a custom GUC variable, so GUC would be left with a pointer to an old value
that might or might not still be valid, and very possibly wouldn't be in
the same place anymore.
While the unload and reload behavior had some usefulness in easing
development of new loadable libraries, it's of no use whatever to normal
users, so just disabling it isn't giving up that much. Someday we might
care to expend the effort to develop safe unload protocols; but even if
we did, there'd be little certainty that every third-party loadable module
was following them, so some security restrictions would still be needed.
Back-patch to 8.2; before that, LOAD was superuser-only anyway.
Security: unprivileged users could crash backend. CVE not assigned yet
functions.
This extends the previous patch that forbade SETting these variables inside
security-definer functions. RESET is equally a security hole, since it
would allow regaining privileges of the caller; furthermore it can trigger
Assert failures and perhaps other internal errors, since the code is not
expecting these variables to change in such contexts. The previous patch
did not cover this case because assign hooks don't really have enough
information, so move the responsibility for preventing this into guc.c.
Problem discovered by Heikki Linnakangas.
Security: no CVE assigned yet, extends CVE-2007-6600
to occur for division by zero, even though the code is carefully avoiding
that. All available evidence is that the only functions affected are
int24div, int48div, and int28div, so patch just those three functions to
include a "return" after the ereport() call.
Backpatch to 8.4 so that the fix can be tested in production builds.
For older branches our recommendation will continue to be to use -O1
on affected platforms (which are mostly non-mainstream anyway).
that's generated for a whole-row Var referencing the subquery, when the
subquery is in the nullable side of an outer join. The previous coding
instead put PlaceHolderVars around the elements of the RowExpr. The effect
was that when the outer join made the subquery outputs go to null, the
whole-row Var produced ROW(NULL,NULL,...) rather than just NULL. There
are arguments afoot about whether those things ought to be semantically
indistinguishable, but for the moment they are not entirely so, and the
planner needs to take care that its machinations preserve the difference.
Per bug #5025.
Making this feasible required refactoring ResolveNew() to allow more caller
control over what is substituted for a Var. I chose to make ResolveNew()
a wrapper around a new general-purpose function replace_rte_variables().
I also fixed the ancient bogosity that ResolveNew might fail to set
a query's hasSubLinks field after inserting a SubLink in it. Although
all current callers make sure that happens anyway, we've had bugs of that
sort before, and it seemed like a good time to install a proper solution.
Back-patch to 8.4. The problem can be demonstrated clear back to 8.0,
but the fix would be too invasive in earlier branches; not to mention
that people may be depending on the subtly-incorrect behavior. The
8.4 series is new enough that fixing this probably won't cause complaints,
but it might in older branches. Also, 8.4 shows the incorrect behavior
in more cases than older branches do, because it is able to flatten
subqueries in more cases.
own database's datfrozenxid, if the current value is old enough to be
forcing autovacuums or warning messages. This ensures that a bogus
value is replaced as soon as possible. Per a comment from Heikki.
Recent commits have removed the various uses it was supporting. It was a
performance bottleneck, according to bug report #4919 by Lauris Ulmanis; seems
it slowed down user creation after a billion users.
to fix the problem that SetClientEncoding needs to be done before
InitializeClientEncoding, as reported by Zdenek Kotala. We get at least
the small consolation of being able to remove the bizarre API detail that
had InitPostgres returning whether user is a superuser.
via the "flat files" facility. This requires making it enough like a backend
to be able to run transactions; it's no longer an "auxiliary process" but
more like the autovacuum worker processes. Also, its signal handling has
to be brought into line with backends/workers. In particular, since it
now has to handle procsignal.c processing, the special autovac-launcher-only
signal conditions are moved to SIGUSR2.
Alvaro, with some cleanup from Tom
XID) in checkpoint records. This eliminates the need to recompute the value
from scratch during database startup, which is one of the two remaining
reasons for the flatfile code to exist. It should also simplify life for
hot-standby operation.
To avoid bloating the checkpoint records unreasonably, I switched from
tracking the oldest database by name to tracking it by OID. This turns
out to save cycles in general (everywhere but the warning-generating
paths, which we hardly care about) and also helps us deal with the case
that the oldest database got dropped instead of being vacuumed. The prior
coding might go for a long time without updating the wrap limit in that case,
which is bad because it might result in a lot of useless autovacuum activity.
(That flat file is now completely useless, but removal will come later.)
To do this, postpone client authentication into the startup transaction
that's run by InitPostgres. We still collect the startup packet and do
SSL initialization (if needed) at the same time we did before. The
AuthenticationTimeout is applied separately to startup packet collection
and the actual authentication cycle. (This is a bit annoying, since it
means a couple extra syscalls; but the signal handling requirements inside
and outside a transaction are sufficiently different that it seems best
to treat the timeouts as completely independent.)
A small security disadvantage is that if the given database name is invalid,
this will be reported to the client before any authentication happens.
We could work around that by connecting to database "postgres" instead,
but consensus seems to be that it's not worth introducing such surprising
behavior.
Processing of all command-line switches and GUC options received from the
client is now postponed until after authentication. This means that
PostAuthDelay is much less useful than it used to be --- if you need to
investigate problems during InitPostgres you'll have to set PreAuthDelay
instead. However, allowing an unauthenticated user to set any GUC options
whatever seems a bit too risky, so we'll live with that.
source directory even for out-of-tree builds. They are now alsl built in
the build tree. This should be more convenient for certain developers'
workflows, and shouldn't really break anything else.
PostgresMain switch. In point of fact, FrontendProtocol is already set
in a backend process, since ProcessStartupPacket() is executed inside
the backend --- it hasn't been run by the postmaster for many years.
And if it were, we'd still certainly want FrontendProtocol to be set before
we get as far as PostgresMain, so that startup errors get reported in the
right protocol.
-v might have some future use in standalone backends, so I didn't go so
far as to remove the switch outright.
Also, initialize FrontendProtocol to 0 not PG_PROTOCOL_LATEST. The only
likely result of presetting it like that is to mask failure-to-set-it
mistakes.
so that their elements are always taken as simple expressions over the
query's input columns. It originally seemed like a good idea to make them
act exactly like GROUP BY and ORDER BY, right down to the SQL92-era behavior
of accepting output column names or numbers. However, that was not such a
great idea, for two reasons:
1. It permits circular references, as exhibited in bug #5018: the output
column could be the one containing the window function itself. (We actually
had a regression test case illustrating this, but nobody thought twice about
how confusing that would be.)
2. It doesn't seem like a good idea for, eg, "lead(foo) OVER (ORDER BY foo)"
to potentially use two completely different meanings for "foo".
Accordingly, narrow down the behavior of window clauses to use only the
SQL99-compliant interpretation that the expressions are simple expressions.
In the original coding, setting a single reloption would cause default
values to be used for all the other reloptions. This is a problem
particularly for autovacuum reloptions.
Itagaki Takahiro
script.
To do this, have pg_ctl pass down its parent shell's PID in an environment
variable PG_GRANDPARENT_PID, and teach CreateLockFile() to disregard that PID
as a false match if it finds it in postmaster.pid. This allows us to cope
with one level of postgres-owned shell process even with pg_ctl in the way,
so it's just as safe as starting the postmaster directly. You still have to
be careful about how you write the initscript though.
Adjust the comments in contrib/start-scripts/ to not deprecate use of
pg_ctl. Also, fix the ROTATELOGS option in the OSX script, which was
indulging in exactly the sort of unsafe coding that renders this fix
pointless :-(. A pipe inside the "sudo" will probably result in more
than one postgres-owned process hanging around.
was incorrectly initialized with timeline ID 0. That rendered the WAL page
unrecoverable, making a subsequent archive recovery stop at that point.
ThisTimeLineID needs to be initialized before calling AdvanceXLInsertBuffer().
This fixes bug #5011 reported by James Bardin. Backpatch to 8.4, as the bug
was introduced by the changes to use of bgwriter for writing the
end-of-archive-recovery checkpoint. Patch by Tom Lane.
Update install-sh to that from Autoconf 2.63, plus our Darwin-specific
changes (which I simplified a bit). install-sh is now able to install
multiple files in one run, so we could simplify our makefiles sometime.
install-sh also now has a -d option to create directories, so we don't need
mkinstalldirs anymore.
Use AC_PROG_MKDIR_P in configure.in, so we can use mkdir -p when available
instead of install-sh -d. For consistency with the rest of the world,
the corresponding make variable has been renamed from $(mkinstalldirs) to
$(MKDIR_P).
Instead of sending stdout/stderr to /dev/null after forking away from the
terminal, send them to postmaster.log within the data directory. Since
this opens the door to indefinite logfile bloat, recommend even more
strongly that log output be redirected when using silent_mode.
Move the postmaster's initial calls of load_hba() and load_ident() down
to after we have started the log collector, if we are going to. This
is so that errors reported by them will appear in the "usual" place.
Reclassify silent_mode as a LOGGING_WHERE, not LOGGING_WHEN, parameter,
since it's got absolutely nothing to do with the latter category.
In passing, fix some obsolete references to -S ... this option hasn't
had that switch letter for a long time.
Back-patch to 8.4, since as of 8.4 load_hba() and load_ident() are more
picky (and thus more likely to fail) than they used to be. This entire
change was driven by a complaint about those errors disappearing into
the bit bucket.
This causes problems when the system load is high, per report from Zdenek
Kotala in <1250860954.1239.114.camel@localhost>; instead of calling kill
directly, have the signal handler set a flag which is checked in ServerLoop.
This way, the handler can return before being called again by a subsequent
signal sent from the autovacuum launcher. Also, increase the sleep in the
launcher in this failure path to 1 second.
Backpatch to 8.3, which is when the signalling between autovacuum
launcher/postmaster was introduced.
Also, add a couple of ReleasePostmasterChildSlot calls in error paths; this
part backpatched to 8.4 which is when the child slot stuff was introduced.
"all tuples visible" flag in heap page headers. The flag update *must*
be applied before calling XLogInsert, but heap_update and the tuple
moving routines in VACUUM FULL were ignoring this rule. A crash and
replay could therefore leave the flag incorrectly set, causing rows
to appear visible in seqscans when they should not be. This might explain
recent reports of data corruption from Jeff Ross and others.
In passing, do a bit of editorialization on comments in visibilitymap.c.
or previously truncated in the current (sub)transaction. This is safe since
if the (sub)transaction later rolls back, we'd just discard the rel's current
physical file anyway. This avoids unreasonable growth in the number of
transient files when a relation is repeatedly truncated. Per a performance
gripe a couple weeks ago from Todd Cook.
values before they get passed to the index access method. This avoids
repeated detoastings that will otherwise ensue as the comparison value
is examined by various index support functions. We have seen a couple of
reports of cases where repeated detoastings result in an order-of-magnitude
slowdown, so it seems worth adding a bit of extra logic to prevent this.
I had previously proposed trying to avoid duplicate detoastings in general,
but this fix takes care of what seems the most important case in practice
with very little effort or risk.
Back-patch to 8.4 so that the PostGIS folk won't have to wait a year to
have this fix in a production release. (The issue exists further back,
of course, but the code's diverged enough to make backpatching further a
higher-risk action. Also it appears that the possible gains may be limited
in prior releases because of different handling of lossy operators.)
about it doesn't simplify the grammar at all, and it does invite confusion
among those who only read the SELECT syntax summary and not the full details.
Per gripe from Jaime Casanova.
physical conversion when there are dropped columns in the same places in
the input and output tupdescs. This avoids possible performance loss from
the recent patch to improve dropped-column handling, in some cases where
the old code would have worked.
truncate_identifier won't do anything if the passed-in strlen is already
less than NAMEDATALEN, which it always would be given the strlcpy usage.
This has been broken since the arrays-of-composite-types code went in.
Arguably truncate_identifier is suffering from excessive optimization
and should always process the string, but for the moment I'll take the
more localized patch.
Per bug #4987.
I mistakenly removed it last month, thinking it was no longer needed ---
but it is still needed for dealing with joininfo lists. Fortunately this
bit of brain fade hadn't made it into any released versions yet.
does match some unique index on the referenced table, but that index is
only deferrably unique. We were doing this nicely for the
default-to-primary-key case, but were being lazy for the other case.
Dean Rasheed
To make this work in the base case, pg_database now has a nailed-in-cache
relation descriptor that is initialized using hardwired knowledge in
relcache.c. This means pg_database is added to the set of relations that
need to have a Schema_pg_xxx macro maintained in pg_attribute.h. When this
path is taken, we'll have to do a seqscan of pg_database to find the row
we need.
In the normal case, we are able to do an indexscan to find the database's row
by name. This is made possible by storing a global relcache init file that
describes only the shared catalogs and their indexes (and therefore is usable
by all backends in any database). A new backend loads this cache file,
finds its database OID after an indexscan on pg_database, and then loads
the local relcache init file for that database.
This change should effectively eliminate number of databases as a factor
in backend startup time, even with large numbers of databases. However,
the real reason for doing it is as a first step towards getting rid of
the flat files altogether. There are still several other sub-projects
to be tackled before that can happen.
to access a Relation entry it had just closed. I happened to be testing with
CLOBBER_CACHE_ALWAYS, which made this a guaranteed core dump (at least on
machines where sprintf %s isn't forgiving of a NULL pointer). It's probably
quite unlikely that it would fail in the field, but a bug is a bug. Fix by
moving the relation_close call down past the logging action.
Test coverage support now covers the entire source tree, including
contrib, instead of just src/backend. In a related but independent
development, the commands make coverage and make coverage-html can be run
in any directory.
This turned out to be much easier than feared. Besides a few ad hoc fixes
to pass the make target down the tree, change all affected makefiles to
list their directories in the SUBDIRS variable, changed from variants like
DIRS and WANTED_DIRS. MSVC build fix was attempted as well.
if a smart shutdown is already in progress. Backpatch to 8.3, this was broken
in the patch that introduced "dead-end backends".
Per report by Itagaki Takahiro, patch by Fujii Masao.
by supporting conversions in places that used to demand exact rowtype match.
Since this issue is certain to come up elsewhere (in fact, already has,
in ExecEvalConvertRowtype), factor out the support code into new core
functions for tuple conversion. I chose to put these in a new source
file since heaptuple.c is already overly long.
Heavily revised version of a patch by Pavel Stehule.
fsync() fails, say "file" rather than "relation" when printing the filename.
This makes messages that display block numbers a bit confusing. For example,
in message 'could not read block 150000 of file "base/1234/5678.1"', 150000
is the block number from the beginning of the relation, ie. segment 0, not
150000th block within that segment. Per discussion, users aren't usually
interested in the exact location within the file, so we can live with that.
To ease constructing error messages, add FilePathName(File) function to
return the pathname of a virtual fd.
Both hex format and the traditional "escape" format are automatically
handled on input. The output format is selected by the new GUC variable
bytea_output.
As committed, bytea_output defaults to HEX, which is an *incompatible
change*. We will keep it this way for awhile for testing purposes, but
should consider whether to switch to the more backwards-compatible
default of ESCAPE before 8.5 is released.
Peter Eisentraut
Add family of functions that did not exist earlier,
mainly due to historical omission. Original patch by
Abhijit Menon-Sen, with review and modifications by
Joe Conway. catversion.h bumped.
values being complained of.
In passing, also remove the arbitrary length limitation in the similar
error detail message for foreign key violations.
Itagaki Takahiro
This patch gets us out from under the Unix limitation of two user-defined
signal types. We already had done something similar for signals directed to
the postmaster process; this adds multiplexing for signals directed to
backends and auxiliary processes (so long as they're connected to shared
memory).
As proof of concept, replace the former usage of SIGUSR1 and SIGUSR2
for backends with use of the multiplexing mechanism. There are still some
hard-wired definitions of SIGUSR1 and SIGUSR2 for other process types,
but getting rid of those doesn't seem interesting at the moment.
Fujii Masao
This was foreseen to be a good idea long ago, but nobody had got round
to doing it. The recent patch for deferred unique constraints made
transformConstraintAttrs() ugly enough that I decided it was time.
This change will also greatly simplify parsing of deferred CHECK constraints,
if anyone ever gets around to implementing that.
While at it, add a location field to Constraint, and use that to provide
an error cursor for some of the constraint-related error messages.
include a fractional part in the output for MILLISECOND and SECOND cases,
rather than truncating the source value. This is what the float-timestamp
code has always done, and it was clearly the code author's intent to do
the same for integer timestamps, but he forgot about integer division in C.
The other datatypes supported by EXTRACT() already do this correctly.
Backpatch to 8.4, so that the default (integer) behavior of that branch will
match the default (float) behavior of older branches. Arguably we should
patch further back, but it's possible that applications are expecting the
broken behavior in older branches. 8.4 is new enough that expectations
shouldn't be too settled.
Per report from Greg Stark.
The current implementation fires an AFTER ROW trigger for each tuple that
looks like it might be non-unique according to the index contents at the
time of insertion. This works well as long as there aren't many conflicts,
but won't scale to massive unique-key reassignments. Improving that case
is a TODO item.
Dean Rasheed
we should ignore NULL array entries, not non-NULL ones. This had the
effect of disabling commit_delay, and could have caused a crash in the
rare race condition the patch was intended to fix.
Bug report and diagnosis by Jeff Janes, in bug #4952.
conindid is the index supporting a constraint. We can use this not only for
unique/primary-key constraints, but also foreign-key constraints, which
depend on the unique index that constrains the referenced columns.
tgconstrindid is just copied from the constraint's conindid field, or is
zero for triggers not associated with constraints.
This is mainly intended as infrastructure for upcoming patches, but it has
some virtue in itself, since it exposes a relationship that you formerly
had to grovel in pg_depend to determine. I simplified one information_schema
view accordingly. (There is a pg_dump query that could also use conindid,
but I left it alone because it wasn't clear it'd get any faster.)
The original syntax made it difficult to add options without making them
into reserved words. This change parenthesizes the options to avoid that
problem, and makes provision for an explicit (and perhaps non-Boolean)
value for each option. The original syntax is still supported, but only
for the two original options ANALYZE and VERBOSE.
As a test case, add a COSTS option that can suppress the planner cost
estimates. This may be useful for including EXPLAIN output in the regression
tests, which are otherwise unable to cope with cross-platform variations in
cost estimates.
Robert Haas
This is believed to not change the output at all, with one known exception:
"Subquery Scan foo" becomes "Subquery Scan on foo". (We can fix that if
anyone complains, but it would be a wart, because the old code was clearly
inconsistent.) The main intention is to remove duplicate coding and
provide a cleaner base for subsequent EXPLAIN patching.
Robert Haas
that memory allocated by starting third party DLLs doesn't end up
conflicting with it.
Hopefully this solves the long-time issue with "could not reattach
to shared memory" errors on Win32.
Patch from Tsutomu Yamada and me, based on idea from Trevor Talbot.
a physical tuple in do_tup_output(). A virtual tuple is easier to set up
and also easier for most tuple receivers to process. Per my comment on
Robert Haas' recent patch in this code.
of individually pfree'ing pass-by-reference transition values. This should
be at least as fast as the prior coding, and it has the major advantage of
clearing out any working data an aggregate function may have stored in or
underneath the aggcontext. This avoids memory leakage when an aggregate
such as array_agg() is used in GROUP BY mode. Per report from Chris Spotts.
Back-patch to 8.4. In principle the problem could arise in prior versions,
but since they didn't have array_agg the issue seems not critical.
for the case that the semijoin was implemented within either input by
unique-ifying its RHS before we test to see if it appears to match the current
join situation. The previous coding would select semijoin logic in situations
where we'd already unique-ified the RHS and joined it to some unrelated
relation(s), and then came to join it to the semijoin's LHS. That still gave
the right answer as far as the semijoin itself was concerned, but would lead
to incorrectly examining only an arbitrary one of the matchable rows from the
unrelated relation(s). The cause of this thinko was incorrect unification of
the pre-8.4 logic for IN joins and OUTER joins --- the comparable case for
outer joins can be handled after making the match test, but that's because
there is nothing like the unique-ification escape hatch for outer joins.
Per bug #4934 from Benjamin Reed.
so it doesn't go through BuildTupleFromCStrings. This is more or less a
wash for current uses, but will avoid inefficiency for planned changes to
EXPLAIN.
Robert Haas
not forced out-of-line unless that is necessary to make the row fit on a
page. Previously, they were forced out-of-line if needed to get the row
down to the default target size (1/4th page).
Kevin Grittner
It appears that, for no particularly good reason, pg_listener.h deviates from
the usual convention for declaring attribute number constants. Normally, it's
#define Anum_{catalog-name}_{column-name} {attribute-number}
pg_listener.h, however substitutes a different string that is similar, but not
the same as, the column name. This change fixes that.
Author: Robert Haas <robertmhaas@gmail.com>
by using a lookup table instead of a naive shift-and-count loop. Based on
code originally posted by Sean Eron Anderson at
http://graphics.stanford.edu/%7eseander/bithacks.html.
Greg Stark did the research and benchmarking to show that this is what
we should use. Jeremy Kerr first noticed that this is a hotspot that
could be optimized, though we ended up not using his suggestion of
platform-specific bit-searching code.
reorder a semijoin into or out of the righthand side of another semijoin,
but actually it doesn't work to reorder it into or out of the righthand
side of a left or antijoin, either. Per bug #4906 from Mathieu Fenniak.
This was sloppy thinking on my part. This identity does work:
( A left join B on (Pab) ) semijoin C on (Pac)
==
( A semijoin C on (Pac) ) left join B on (Pab)
but I failed to see that that doesn't mean this does:
( A left join B on (Pab) ) semijoin C on (Pbc)
!=
A left join ( B semijoin C on (Pbc) ) on (Pab)
foo <> false, along with its previous duties of simplifying foo = true
and foo = false. (All of these are equivalent to just foo or NOT foo
as the case may be.) It's not clear how often this is really useful;
but it costs almost nothing to do, and it seems some people think we
should be smart about such cases. Per recent bug report.
sequence, even when the input "tour" doesn't lead directly to such a sequence.
The stack logic that was added in 2004 only supported cases where relations
that had to be joined to each other (due to join order restrictions) were
adjacent in the tour. However, relying on a random search to figure that out
is tremendously inefficient in large join problems, and could even fail
completely (leading to "failed to make a valid plan" errors) if
random_init_pool ran out of patience. It seems better to make the
tour-to-plan transformation a little bit fuzzier so that every tour can form
a legal plan, even though this means that apparently different tours will
sometimes yield the same plan.
In the same vein, get rid of the logic that knew that tours (a,b,c,d,...)
are the same as tours (b,a,c,d,...), and therefore insisted the latter
are invalid. The chance of generating two tours that differ only in
this way isn't that high, and throwing out 50% of possible tours to
avoid such duplication seems more likely to waste valuable genetic-
refinement generations than to do anything useful.
This leaves us with no cases in which geqo_eval will deem a tour invalid,
so get rid of assorted kluges that tried to deal with such cases, in
particular the undocumented assumption that DBL_MAX is an impossible
plan cost.
This is all per testing of Robert Haas' lets-remove-the-collapse-limits
patch. That idea has crashed and burned, at least for now, but we still
got something useful out of it.
It's possible we should back-patch this change, since the "failed to make a
valid plan" error can happen in existing releases; but I'd rather not until
it has gotten more testing.
by unique-ifying the RHS and then inner-joining to some other relation,
that is not grounds for violating the RHS of some other outer join.
Noticed while regression-testing new GEQO code, which will blindly follow
any path that join_is_legal says is legal, and then complain later if that
leads to a dead end.
I'm not certain that this can result in any visible failure in 8.4: the
mistake may always be masked by the fact that subsequent attempts to join
the rest of the RHS of the other join will fail. But I'm not certain it
can't, either, and it's definitely not operating as intended. So back-patch.
The added regression test depends on the new no-failures-allowed logic
that I'm about to commit in GEQO, so no point back-patching that.
memory leakage in error recovery. We were calling FreeExprContext, and
therefore invoking ExprContextCallback callbacks, in both normal and error
exits from subtransactions. However this isn't very safe, as shown in
recent trouble report from Frank van Vugt, in which releasing a tupledesc
refcount failed. It's also unnecessary, since the resources that callbacks
might wish to release should be cleaned up by other error recovery mechanisms
(ie the resource owners). We only really want FreeExprContext to release
memory attached to the exprcontext in the error-exit case. So, add a bool
parameter to FreeExprContext to tell it not to call the callbacks.
A more general solution would be to pass the isCommit bool parameter on to
the callbacks, so they could do only safe things during error exit. But
that would make the patch significantly more invasive and possibly break
third-party code that registers ExprContextCallback callbacks. We might want
to do that later in HEAD, but for now I'll just do what seems reasonable to
back-patch.
that the sanity checking I added to create_mergejoin_plan() in 8.3 was a
few bricks shy of a load: the mergeclauses could reference pathkeys in a
noncanonical order such as x,y,x, not only cases like x,x,y which is all
that the code had allowed for. The odd cases only turn up when using
redundant clauses in an outer join condition, which is why no one had
noticed before.
random number seed each time. This is how it used to work years ago, but
we got rid of the seed reset because it was resetting the main random()
sequence and thus having undesirable effects on the rest of the system.
To fix, establish a private random number state for each execution of
geqo(), and initialize the state using the new GUC variable geqo_seed.
People who want to experiment with different random searches can do so
by changing geqo_seed, but you'll always get the same plan for the same
value of geqo_seed (if holding all other planner inputs constant, of course).
The new state is kept in PlannerInfo by adding a "void *" field reserved
for use by join_search hooks. Most of the rather bulky code changes in
this commit are just arranging to pass PlannerInfo around to all the GEQO
functions (many of which formerly didn't receive it).
Andres Freund, with some editorialization by Tom
This alters various incidental uses of C++ key words to use other similar
identifiers, so that a C++ compiler won't choke outright. You still
(probably) need extern "C" { }; around the inclusion of backend headers.
based on a patch by Kurt Harriman <harriman@acm.org>
Also add a script cpluspluscheck to check for C++ compatibility in the
future. As of right now, this passes without error for me.
Changes:
Pass in the keyword lookup array instead of having it be hardwired.
(This incidentally allows elimination of some duplicate coding in ecpg.)
Re-order the token declarations in gram.y so that non-keyword tokens have
numbers that won't change when keywords are added or removed.
Add ".." and ":=" to the set of tokens recognized by scan.l. (Since these
combinations are nowhere legal in core SQL, this does not change anything
except the precise wording of the error you get when you write this.)
RevalidateCachedPlan. This is to avoid a "SPI_ERROR_CONNECT" failure when
the planner calls a SPI-using function and we are already inside one.
The alternative fix is to expect callers of RevalidateCachedPlan to do this,
which seems likely to result in additional hard-to-detect bugs of omission.
Per reports from Frank van Vugt and Marek Lewczuk.
Back-patch to 8.3. It's much harder to trigger the bug in 8.3, due to a
smaller set of cases in which plans can be invalidated, but it could happen.
(I think perhaps only a SI reset event could make 8.3 fail here, but that's
certainly within the realm of possibility.)
size_t arguments, the emitted scanner actually prototypes them with
type yy_size_t, which is sometimes not the same thing depending on
flex version and platform. Easiest fix seems to be to use yy_size_t.
Per buildfarm results.
of features added to flex and bison since this code was originally written.
This change doesn't in itself offer any new capability, but it's needed
infrastructure for planned improvements in plpgsql.
Another feature now available in flex is the ability to make it use palloc
instead of malloc, so do that to avoid possible memory leaks. (We should
at some point change the other lexers likewise, but this commit doesn't
touch them.)
distinction between the external API (parser.h) and declarations that only
need to be visible within the raw parser code (gramparse.h, which now is only
included by parser.c, gram.y, scan.l, and keywords.c). This is in preparation
for the upcoming change to a reentrant lexer, which will require referencing
YYSTYPE in the declarations of base_yylex and filtered_base_yylex, hence
gram.h will have to be included by gramparse.h. We don't want any more files
than absolutely necessary to depend on gram.h, so some cleanup is called for.
RelOptInfo targetlist. It used to be that the only possibility other than
a Var was a RowExpr representing a whole-row child Var, but as of 8.4's
expanded ability to flatten appendrel members, we can get arbitrary expressions
in there. Use the expression's type info and get_typavgwidth() to produce
an at-least-marginally-sane result. Note that get_typavgwidth()'s fallback
estimate (32 bytes) is the same as what was here before, so there will be
no behavioral change for RowExprs. Noted while looking at recent gripe
about constant quals pushed down to FunctionScan appendrel members ...
not only were we failing to recognize the constant qual, we were getting
the width estimate wrong :-(
LC_CTYPE settings to children via BackendParameters. Per discussion,
the postmaster is now just using system defaults anyway, so we might as
well save a few cycles during backend startup.
Otherwise, the LC_CTYPE/COLLATE setting gets reverted when using plperl, which
leads to incorrect query results and index corruption.
This was accidentally broken in the per-database locale patch in 8.4. Pointed
out by Andrew Gierth.
For character types with typmod, character_octet_length columns in the
information schema now show the maximum character length times the
maximum length of a character in the server encoding, instead of some
huge value as before.
timestamp_trunc, timestamptz_trunc, and interval_trunc(). This change
only affects the float-datetime case; the integer-datetime case already
behaved like truncation instead of rounding. Per gripe from Mario Splivalo.
This is a pre-existing issue but I'm choosing not to backpatch, because
it's such a corner case and there have not been prior complaints. The
issue is largely moot anyway given the trend towards integer datetimes.
substituting a child rel's output expressions into the appendrel's restriction
clauses yields a pseudoconstant restriction. We might be able to skip scanning
that child rel entirely (if we get constant FALSE), or generate a one-time
filter. 8.3 more or less accidentally generated plans that weren't completely
stupid in these cases, but that was only because an extra recursive level of
subquery_planner() always occurred and allowed const-simplification to happen.
8.4's ability to pull up appendrel members with non-Var outputs exposes the
fact that we need to work harder here. Per gripe from Sergey Burladyan.
parentheses around the <query expression body> that follows a WITH clause, eg
with cte(foo) as ( values(0) ) ((select foo from cte));
This seems to be just an oversight/thinko in gram.y. Noted while
experimenting with bug #4902.
the "cteParam" as a proxy for the possibility that the underlying CTE plan
depends on outer-level variables or Params, but that doesn't work very well
because it sometimes causes calling subqueries to be treated as SubPlans when
they could be InitPlans. This is inefficient and also causes the outright
failure exhibited in bug #4902. Instead, leave the cteParam out of it and
copy the underlying CTE plan's extParams directly. Per bug #4902 from
Marko Tiikkaja.
archive recovery. Invent a separate state variable and inquiry function
for XLogInsertAllowed() to clarify some tests and make the management of
writing the end-of-recovery checkpoint less klugy. Fix several places
that were incorrectly testing InRecovery when they should be looking at
RecoveryInProgress or XLogInsertAllowed (because they will now be executed
in the bgwriter not startup process). Clarify handling of bad LSNs passed
to XLogFlush during recovery. Use a spinlock for setting/testing
SharedRecoveryInProgress. Improve quite a lot of comments.
Heikki and Tom
during it:
When bgwriter is active, the startup process can't perform mdsync() correctly
because it won't see the fsync requests accumulated in bgwriter's private
pendingOpsTable. Therefore make bgwriter responsible for the end-of-recovery
checkpoint as well, when it's active.
When bgwriter is active (= archive recovery), the startup process must not
accumulate fsync requests to its own pendingOpsTable, since bgwriter won't
see them there when it performs restartpoints. Make startup process drop its
pendingOpsTable when bgwriter is launched to avoid that.
Update minimum recovery point one last time when leaving archive recovery.
It won't be updated by the end-of-recovery checkpoint because XLogFlush()
sees us as out of recovery already.
This fixes bug #4879 reported by Fujii Masao.
acting like runs inside WAL recovery, but it doesn't. I must've copy-pasted
this from a redo-function in the relation forks patch. Noticed by Tom Lane
while he was looking through callers of smgrdounlink().
a number of other geometric operators also depend on. It miscalculated the
slope of the perpendicular to the given line segment anytime that slope was
other than 0, infinite, or +/-1. In some cases the error would be masked
because the true closest point on the line segment was one of its endpoints
rather than the intersection point, but in other cases it could give an
arbitrarily bad answer. Per bug #4872 from Nick Roosevelt.
Bug goes clear back to Berkeley days, so patch all supported branches.
Make a couple of cosmetic adjustments while at it.
of the 256KB limit originally enforced by a patch committed 2008-11-06.
Per recent test results, the smaller size resulted in an undesirable decrease
in bulk data loading speed, due to COPY processing frequently getting blocked
for WAL flushing. This area might need more tweaking later, but this setting
seems to be good enough for 8.4.
even when not in FM mode. This improves compatibility with Oracle and with
our pre-8.4 behavior, as per bug #4862.
Brendan Jurd
Add a couple of regression test cases for this. In passing, get rid of the
labeling of the individual test cases; doesn't seem to be good for anything
except causing extra work when inserting a test...
Tom Lane
ArrayBuildState, per trouble report from Merlin Moncure. By adopting
this fix, we are essentially deciding that aggregate final-functions
should not modify their inputs ever. Adjust documentation and comments
to match that conclusion.
types in CREATE TRIGGER. While at it, clean up the amazingly tedious and
inextensible way that the trigger event type list was handled. Per report
from Greg Sabino Mullane.
aggregated tuple of a run. Per report from Laurenz Albe. This is a new
bug in 8.4, but only because prior versions rejected SRFs in an Agg plan
node altogether.
function returning setof record. This used to work, more or less
accidentally, but I had broken it while extending the code to allow
materialize-mode functions to be called in select lists. Add a regression
test case so it doesn't get broken again. Per gripe from Greg Davidson.
rsinfo->expectedDesc == NULL in deflist_to_tuplestore(), but that doesn't
look very safe to me. Noted in passing while studying problem report
from Greg Davidson.
node starts from the same place as the first scan did. This avoids surprising
behavior of scrollable and WITH HOLD cursors, as seen in Mark Kirkwood's bug
report of yesterday.
It's not entirely clear whether a rescan should be forced to drop out of the
syncscan mode, but for the moment I left the code behaving the same on that
point. Any change there would only be a performance and not a correctness
issue, anyway.
Back-patch to 8.3, since the unstable behavior was created by the syncscan
patch.
eg Japan. Report and fix by Itagaki Takahiro. Also fix CASHDEBUG printout
format for branches with 64-bit money type, and some minor comment cleanup.
Back-patch to 7.4, because it's broken all the way back.
In particular, always show 0 for the date type instead of null, and show
6 (the default) for time, timestamp, and interval without a declared
precision. This is now in fuller conformance with the SQL standard.
Also clarify the documentation about this.
discovered and analyzed by Konstantin Izmailov and Tom Lane
more consistent with other cases, by having an unlabeled integer field
be treated as a number of minutes or seconds respectively. These cases
are outside the spec (which insists on full "dd hh:mm" or "dd hh:mm:ss"
input respectively), so it's not much help to us in deciding what to do.
But with this change, it's uniformly the case that an unlabeled integer
will be considered as being a number of the interval's rightmost field.
The change also takes us back to the 8.3 behavior of throwing error
for certain ambiguous inputs such as INTERVAL '1 2' DAY TO MINUTE.
Per recent discussion.
Sergey Burladyan, there are at least some dank corners of libxml2 that
assume this behavior, even though their published documentation suggests
they shouldn't.
This is only really a live problem in 8.3, but the code is still there
for possible debugging use in HEAD, so patch both branches.
"array_agg_finalfn(null)". We should modify pg_proc entries to prevent this
query from being accepted, but let's just make the function itself secure too.
Per my note of today.
behavior in cases where we don't know the heap tuple count accurately; in
particular partial vacuum, but this also makes the API a bit more useful
for ANALYZE. This patch adds "estimated_count" flags to both structs so
that an approximate count can be flagged as such, and adjusts the logic
so that approximate counts are not used for updating pg_class.reltuples.
This fixes my previous complaint that VACUUM was putting ridiculous values
into pg_class.reltuples for indexes. The actual impact of that bug is
limited, because the planner only pays attention to reltuples for an index
if the index is partial; which probably explains why beta testers hadn't
noticed a degradation in plan quality from it. But it needs to be fixed.
The whole thing is a bit messy and should be redesigned in future, because
reltuples now has the potential to drift quite far away from reality when
a long period elapses with no non-partial vacuums. But this is as good as
it's going to get for 8.4.
is supposed to remove duplicate heap TIDs, we have to be sure to reduce the
tuple size and posting-item count accordingly in addItemPointersToTuple().
Failing to do so resulted in the effective injection of garbage TIDs into the
index contents, ie, whatever happened to be in the memory palloc'd for the
new tuple. I'm not sure that this fully explains the index corruption
reported by Tatsuo Ishii, but the test case I'm using no longer fails.
by extending the ereport() API to cater for pluralization directly. This
is better than the original method of calling ngettext outside the elog.c
code because (1) it avoids double translation, which wastes cycles and in
the worst case could give a wrong result; and (2) it avoids having to use
a different coding method in PL code than in the core backend. The
client-side uses of ngettext are not touched since neither of these concerns
is very pressing in the client environment. Per my proposal of yesterday.
symbolic links with the -l option, and as Fujii Masao pointed out we ended up
overwriting files in the archive directory before this patch. Patch by
Aidan Van Dyk, Fujii Masao and me.
Backpatch to 8.3, where pg_standby was introduced.
grounds that they don't fit into the specified interval qualifier (typmod).
This behavior, while of long standing, is clearly wrong per spec --- for
example the value INTERVAL '999' SECOND means 999 seconds and should not be
reduced to less than 60 seconds.
In some cases there could be grounds to raise an error if higher-order field
values are not given as zero; for example '1 year 1 month'::INTERVAL MONTH
should arguably be taken as an error rather than equivalent to 13 months.
However our internal representation doesn't allow us to do that in a fashion
that would consistently reject all and only the cases that a strict reading
of the spec would suggest. Also, seeing that for example INTERVAL '13' MONTH
will print out as '1 year 1 mon', we have to be careful not to create a
situation where valid data will fail to dump and reload. The present patch
therefore takes the attitude of not throwing an error in any such case.
We might want to revisit that in future but it would take more redesign
than seems prudent in late beta.
Per a complaint from Sebastien Flaesch and subsequent discussion. While
at other times we might have just postponed such an issue to the next
development cycle, 8.4 already has changed the parsing of interval literals
quite a bit in an effort to accept all spec-compliant cases correctly.
This seems like a change that should be part of that rather than coming
along later.
YEAR, DECADE, CENTURY, or MILLENIUM fields, just as it always has done for
other types of fields. The previous behavior seems to have been a hack to
avoid defining bit-positions for all these field types in DTK_M() masks,
rather than something that was really considered to be desired behavior.
But there is room in the masks for these, and we really need to tighten up
at least the behavior of DAY and YEAR fields to avoid unexpected behavior
associated with the 8.4 changes to interpret ambiguous fields based on the
interval qualifier (typmod) value. Per my example and proposed patch.
queries frequently took no lock at all on individual indexes. That's not
true any more, but we still need lock on the parent table to make it safe
to use cached lists of index OIDs.
throwing an error as 8.4 had been doing. The error interfered with porting
old database definitions (particularly for pg_migrator) without really buying
any safety. Per bug #4817 and subsequent discussion.
an expression that's not supposed to contain variables. Per discussion
with Gevik Babakhani, this eliminates the need for an ugly kluge (namely,
specifying some unrelated relation name). Remove one such kluge from
pg_dump.
of time values that would not be accepted via textual input.
Per gripe from Andrew McNamara.
This is potentially a back-patchable bug fix, but for the moment it doesn't
seem sufficiently high impact to justify doing that.
this case is worth a special code path, but a special code path that gets
the boundary condition wrong is definitely no good. Per bug #4821 from
Andrew Gierth.
In passing, clean up some minor code formatting issues (excess parentheses
and blank lines in odd places).
Back-patch to 8.3, where the bug was introduced.
there's no analyzable attributes or indexes. We also used to report 0 live
and dead tuples for such tables, which messed with autovacuum threshold
calculations.
This fixes bug #4812 reported by George Su. Backpatch back to 8.1.
copies?) to ensure they really don't run proc_exit/shmem_exit callbacks,
as was intended. I broke this behavior recently by installing atexit
callbacks without thinking about the one case where we truly don't want
to run those callback functions. Noted in an example from Dave Page.
is run at the end of archive recovery, providing a chance to do external
cleanup. Modify pg_standby so that it no longer removes the trigger file,
that is to be done using the recovery_end_command now.
Provide a "smart" failover mode in pg_standby, where we don't fail over
immediately, but only after recovering all unapplied WAL from the archive.
That gives you zero data loss assuming all WAL was archived before
failover, which is what most users of pg_standby actually want.
recovery_end_command by Simon Riggs, pg_standby changes by Fujii Masao and
myself.
that aren't RELKIND_RELATION or RELKIND_VIEW, and to disallow attaching rules
to system relations unless allowSystemTableMods is on. This is to make the
behavior of CREATE RULE more like CREATE TRIGGER, which disallows the
comparable cases. Per discussion of bug #4808.
redirecting libxml's allocations into a Postgres context. Instead, just let
it use malloc directly, and add PG_TRY blocks as needed to be sure we release
libxml data structures in error recovery code paths. This is ugly but seems
much more likely to play nicely with third-party uses of libxml, as seen in
recent trouble reports about using Perl XML facilities in pl/perl and bug
#4774 about contrib/xml2.
I left the code for allocation redirection in place, but it's only
built/used if you #define USE_LIBXMLCONTEXT. This is because I found it
useful to corral libxml's allocations in a palloc context when hunting
for libxml memory leaks, and we're surely going to have more of those
in the future with this type of approach. But we don't want it turned on
in a normal build because it breaks exactly what we need to fix.
I have not re-indented most of the code sections that are now wrapped
by PG_TRY(); that's for ease of review. pg_indent will fix it.
This is a pre-existing bug in 8.3, but I don't dare back-patch this change
until it's gotten a reasonable amount of field testing.