Tom Lane [Tue, 10 Jul 2012 03:22:55 +0000 (23:22 -0400)]
Refactor pattern_fixed_prefix() to avoid dealing in incomplete patterns.
Previously, pattern_fixed_prefix() was defined to return whatever fixed
prefix it could extract from the pattern, plus the "rest" of the pattern.
That definition was sensible for LIKE patterns, but not so much for
regexes, where reconstituting a valid pattern minus the prefix could be
quite tricky (certainly the existing code wasn't doing that correctly).
Since the only thing that callers ever did with the "rest" of the pattern
was to pass it to like_selectivity() or regex_selectivity(), let's cut out
the middle-man and just have pattern_fixed_prefix's subroutines do this
directly. Then pattern_fixed_prefix can return a simple selectivity
number, and the question of how to cope with partial patterns is removed
from its API specification.
While at it, adjust the API spec so that callers who don't actually care
about the pattern's selectivity (which is a lot of them) can pass NULL for
the selectivity pointer to skip doing the work of computing a selectivity
estimate.
This patch is only an API refactoring that doesn't actually change any
processing, other than allowing a little bit of useless work to be skipped.
However, it's necessary infrastructure for my upcoming fix to regex prefix
extraction, because after that change there won't be any simple way to
identify the "rest" of the regex, not even to the low level of fidelity
needed by regex_selectivity. We can cope with that if regex_fixed_prefix
and regex_selectivity communicate directly, but not if we have to work
within the old API. Hence, back-patch to all active branches.
Tom Lane [Mon, 9 Jul 2012 03:51:08 +0000 (23:51 -0400)]
Fix planner to pass correct collation to operator selectivity estimators.
We can do this without creating an API break for estimation functions
by passing the collation using the existing fmgr functionality for
passing an input collation as a hidden parameter.
The need for this was foreseen at the outset, but we didn't get around to
making it happen in 9.1 because of the decision to sort all pg_statistic
histograms according to the database's default collation. That meant that
selectivity estimators generally need to use the default collation too,
even if they're estimating for an operator that will do something
different. The reason it's suddenly become more interesting is that
regexp interpretation also uses a collation (for its LC_TYPE not LC_COLLATE
property), and we no longer want to use the wrong collation when examining
regexps during planning. It's not that the selectivity estimate is likely
to change much from this; rather that we are thinking of caching compiled
regexps during planner estimation, and we won't get the intended benefit
if we cache them with a different collation than the executor will use.
Back-patch to 9.1, both because the regexp change is likely to get
back-patched and because we might as well get this right in all
collation-supporting branches, in case any third-party code wants to
rely on getting the collation. The patch turns out to be minuscule
now that I've done it ...
Tom Lane [Sat, 7 Jul 2012 21:39:50 +0000 (17:39 -0400)]
Simplify and document regex library's compact-NFA representation.
The previous coding abused the first element of a cNFA state's arcs list
to hold a per-state flag bit, which was confusing, undocumented, and not
even particularly efficient. Get rid of that in favor of a separate
"stflags" vector. Since there's only one bit in use, I chose to allocate a
char per state; we could possibly replace this with a bitmap at some point,
but that would make accesses a little slower. It's already about 8X
smaller than before, so let's not get overly tense.
Also document the representation better than it was before, which is to say
not at all.
This patch is a byproduct of investigations towards extracting a "fixed
prefix" string from the compact-NFA representation of regex patterns.
Might need to back-patch it if we decide to back-patch that fix, but for
now it's just code cleanup so I'll just put it in HEAD.
Tom Lane [Thu, 5 Jul 2012 21:15:05 +0000 (17:15 -0400)]
Don't try to trim "../" in join_path_components().
join_path_components() tried to remove leading ".." components from its
tail argument, but it was not nearly bright enough to do so correctly
unless the head argument was (a) absolute and (b) canonicalized.
Rather than try to fix that logic, let's just get rid of it: there is no
correctness reason to remove "..", and cosmetic concerns can be taken
care of by a subsequent canonicalize_path() call. Per bug #6715 from
Greg Davidson.
Back-patch to all supported branches. It appears that pre-9.2, this
function is only used with absolute paths as head arguments, which is why
we'd not noticed the breakage before. However, third-party code might be
expecting this function to work in more general cases, so it seems wise
to back-patch.
In HEAD and 9.2, also make some minor cosmetic improvements to callers.
Revert part of the previous patch that avoided using PLy_elog().
That caused the plpython_unicode regression test to fail on SQL_ASCII
encoding, as evidenced by the buildfarm. The reason is that with the patch,
you don't get the detail in the error message that you got before. That
detail is actually very informative, so rather than just adjust the expected
output, let's revert that part of the patch for now to make the buildfarm
green again, and figure out some other way to avoid the recursion of
PLy_elog() that doesn't lose the detail.
Fix mapping of PostgreSQL encodings to Python encodings.
Windows encodings, "win1252" and so forth, are named differently in Python,
like "cp1252". Also, if the PyUnicode_AsEncodedString() function call fails
for some reason, use a plain ereport(), not a PLy_elog(), to report that
error. That avoids recursion and crash, if PLy_elog() tries to call
PLyUnicode_Bytes() again.
This fixes bug reported by Asif Naeem. Backpatch down to 9.0, before that
plpython didn't even try these conversions.
Jan UrbaĆski, with minor comment improvements by me.
Tom Lane [Thu, 5 Jul 2012 18:00:40 +0000 (14:00 -0400)]
Remove support for using wait3() in place of waitpid().
All Unix-oid platforms that we currently support should have waitpid(),
since it's in V2 of the Single Unix Spec. Our git history shows that
the wait3 code was added to support NextStep, which we officially dropped
support for as of 9.2. So get rid of the configure test, and simplify the
macro spaghetti in reaper(). Per suggestion from Fujii Masao.
Robert Haas [Wed, 4 Jul 2012 19:52:35 +0000 (15:52 -0400)]
Increase the maximum initdb-configured value for shared_buffers to 128MB.
The old value of 32MB has been around for a very long time, and in the
meantime typical system memories have become vastly larger. Also, now
that we no longer depend on being able to fit the entirety of our
shared memory segment into the system's limit on System V shared
memory, there's a much better chance of the higher limit actually
proving productive.
Magnus Hagander [Wed, 4 Jul 2012 13:13:09 +0000 (15:13 +0200)]
Set the write location in the pg_receivexlog status messages
This makes it possible for the master to track how much data has
actually been written my pg_receivexlog - and not just how much
has been sent towards it.
Magnus Hagander [Wed, 4 Jul 2012 13:10:46 +0000 (15:10 +0200)]
Always treat a standby returning an an invalid flush location as async
This ensures that a standby such as pg_receivexlog will not be selected
as sync standby - which would cause the master to block waiting for
a location that could never happen.
Magnus Hagander [Wed, 4 Jul 2012 07:22:21 +0000 (09:22 +0200)]
Remove reference to default wal_buffers being 8
This hasn't been true since 9.1, when the default was changed to -1.
Remove the reference completely, keeping the discussion of the parameter
and it's shared memory effects on the config page.
Per bug #6593, REASSIGN OWNED fails when the affected role has created
an extension. Even though the user related to the extension is not
nominally the owner, its OID appears on pg_shdepend and thus causes
problems when the user is to be dropped.
This commit adds code to change the "ownership" of the extension itself,
not of the contained objects. This is fine because it's currently only
called from REASSIGN OWNED, which would also modify the ownership of the
contained objects. However, this is not sufficient for a working ALTER
OWNER implementation extension.
Back-patch to 9.1, where extensions were introduced.
Tom Lane [Mon, 2 Jul 2012 15:35:21 +0000 (11:35 -0400)]
Fix to_date's handling of year 519.
A thinko in commit 029dfdf1157b6d837a7b7211cd35b00c6bcd767c caused the year
519 to be handled differently from either adjacent year, which was not the
intention AFAICS. Report and diagnosis by Marc Cousin.
In passing, remove redundant re-tests of year value.
Robert Haas [Mon, 2 Jul 2012 14:26:31 +0000 (10:26 -0400)]
Make commit_delay much smarter.
Instead of letting every backend participating in a group commit wait
independently, have the first one that becomes ready to flush WAL wait
for the configured delay, and let all the others wait just long enough
for that first process to complete its flush. This greatly increases
the chances of being able to configure a commit_delay setting that
actually improves performance.
As a side consequence of this change, commit_delay now affects all WAL
flushes, rather than just commits. There was some discussion on
pgsql-hackers about whether to rename the GUC to, say, wal_flush_delay,
but in the absence of consensus I am leaving it alone for now.
Peter Geoghegan, with some changes, mostly to the documentation, by me.
Robert Haas [Mon, 2 Jul 2012 13:36:34 +0000 (09:36 -0400)]
Make walsender more responsive.
Per testing by Andres Freund, this improves replication performance
and reduces replication latency and latency jitter. I was a bit
concerned about moving more work into XLogInsert, but testing seems
to show that it's not a problem in practice.
Along the way, improve comments for WaitLatchOrSocket.
Andres Freund. Review and stylistic cleanup by me.
Tom Lane [Sun, 1 Jul 2012 21:12:49 +0000 (17:12 -0400)]
Fix race condition in enum value comparisons.
When (re) loading the typcache comparison cache for an enum type's values,
use an up-to-date MVCC snapshot, not the transaction's existing snapshot.
This avoids problems if we encounter an enum OID that was created since our
transaction started. Per report from Andres Freund and diagnosis by Robert
Haas.
To ensure this is safe even if enum comparison manages to get invoked
before we've set a transaction snapshot, tweak GetLatestSnapshot to
redirect to GetTransactionSnapshot instead of throwing error when
FirstSnapshotSet is false. The existing uses of GetLatestSnapshot (in
ri_triggers.c) don't care since they couldn't be invoked except in a
transaction that's already done some work --- but it seems just conceivable
that this might not be true of enums, especially if we ever choose to use
enums in system catalogs.
Note that the comparable coding in enum_endpoint and enum_range_internal
remains GetTransactionSnapshot; this is perhaps debatable, but if we
changed it those functions would have to be marked volatile, which doesn't
seem attractive.
Back-patch to 9.1 where ALTER TYPE ADD VALUE was added.
Tom Lane [Sun, 1 Jul 2012 02:27:49 +0000 (22:27 -0400)]
Suppress compiler warnings in readfuncs.c.
Commit 7357558fc8866e3a449aa9473c419b593d67b5b6 introduced "(void) token;"
into the READ_TEMP_LOCALS() macro, to suppress complaints from gcc 4.6
when the value of token was not used anywhere in a particular node-read
function. However, this just moved the warning around: inspection of
buildfarm results shows that some compilers are now complaining that token
is being read before it's set. Revert the READ_TEMP_LOCALS() macro change
and instead put "(void) token;" into READ_NODE_FIELD(), which is the
principal culprit for cases where the warning might occur. In principle we
might need the same in READ_BITMAPSET_FIELD() and/or READ_LOCATION_FIELD(),
but it seems unlikely that a node would consist only of such fields, so
I'll leave them alone for now.
Tom Lane [Sat, 30 Jun 2012 21:19:46 +0000 (17:19 -0400)]
Declare AnonymousShmem pointer as "void *".
The original coding had it as "PGShmemHeader *", but that doesn't offer any
notational benefit because we don't dereference it. And it was resulting
in compiler warnings on some platforms, notably buildfarm member
castoroides, where mmap() and munmap() are evidently declared to take and
return "char *".
Tom Lane [Sat, 30 Jun 2012 20:43:50 +0000 (16:43 -0400)]
Prevent CREATE TABLE LIKE/INHERITS from (mis) copying whole-row Vars.
If a CHECK constraint or index definition contained a whole-row Var (that
is, "table.*"), an attempt to copy that definition via CREATE TABLE LIKE or
table inheritance produced incorrect results: the copied Var still claimed
to have the rowtype of the source table, rather than the created table.
For the LIKE case, it seems reasonable to just throw error for this
situation, since the point of LIKE is that the new table is not permanently
coupled to the old, so there's no reason to assume its rowtype will stay
compatible. In the inheritance case, we should ideally allow such
constraints, but doing so will require nontrivial refactoring of CREATE
TABLE processing (because we'd need to know the OID of the new table's
rowtype before we adjust inherited CHECK constraints). In view of the lack
of previous complaints, that doesn't seem worth the risk in a back-patched
bug fix, so just make it throw error for the inheritance case as well.
Along the way, replace change_varattnos_of_a_node() with a more robust
function map_variable_attnos(), which is capable of being extended to
handle insertion of ConvertRowtypeExpr whenever we get around to fixing
the inheritance case nicely, and in the meantime it returns a failure
indication to the caller so that a helpful message with some context can be
thrown. Also, this code will do the right thing with subselects (if we
ever allow them in CHECK or indexes), and it range-checks varattnos before
using them to index into the map array.
Per report from Sergey Konoplev. Back-patch to all supported branches.
Peter Eisentraut [Sat, 30 Jun 2012 12:39:16 +0000 (15:39 +0300)]
initdb: Update check_need_password for new options
Change things so that something like initdb --auth-local=peer
--auth-host=md5 does not cause a "must specify a password" error,
like initdb -A md5 does.
Validate xlog record header before enlarging the work area to store it.
If the record header is garbled, we're now quite likely to notice it before
we try to make a bogus memory allocation and run out of memory. That can
still happen, if the xlog record is split across pages (we cannot verify
the record header until reading the next page in that scenario), but this
reduces the chances. An out-of-memory is treated as a corrupt record
anyway, so this isn't a correctness issue, just a case of giving a better
error message.
Alvaro Herrera [Fri, 29 Jun 2012 03:27:00 +0000 (23:27 -0400)]
Make the pg_upgrade log files contain actual commands
Now the log file not only contains the output from commands executed by
system(), but also what command it was in the first place. This
arrangement makes debugging a lot simpler.
Tom Lane [Fri, 29 Jun 2012 04:51:34 +0000 (00:51 -0400)]
Fix NOTIFY to cope with I/O problems, such as out-of-disk-space.
The LISTEN/NOTIFY subsystem got confused if SimpleLruZeroPage failed,
which would typically happen as a result of a write() failure while
attempting to dump a dirty pg_notify page out of memory. Subsequently,
all attempts to send more NOTIFY messages would fail with messages like
"Could not read from file "pg_notify/nnnn" at offset nnnnn: Success".
Only restarting the server would clear this condition. Per reports from
Kevin Grittner and Christoph Berg.
Back-patch to 9.0, where the problem was introduced during the
LISTEN/NOTIFY rewrite.
Alvaro Herrera [Fri, 29 Jun 2012 03:37:27 +0000 (23:37 -0400)]
pg_upgrade: fix off-by-one mistake in snprintf
snprintf counts trailing NUL towards the char limit. Failing to account
for that was causing an invalid value to be passed to pg_resetxlog -l,
aborting the upgrade process.
Tom Lane [Thu, 28 Jun 2012 18:18:31 +0000 (14:18 -0400)]
Provide MAP_FAILED if sys/mman.h doesn't.
On old HPUX this has to be #defined to -1. It might be that other values
are required on other dinosaur systems, but we'll worry about that when
and if we get reports.
Peter Eisentraut [Thu, 28 Jun 2012 17:05:36 +0000 (20:05 +0300)]
Further fix install program detection
The $(or) make function was introduced in GNU make 3.81, so the
previous coding didn't work in 3.80. Write it differently, and
improve the variable naming to make more sense in the new coding.
Robert Haas [Thu, 28 Jun 2012 15:05:16 +0000 (11:05 -0400)]
Dramatically reduce System V shared memory consumption.
Except when compiling with EXEC_BACKEND, we'll now allocate only a tiny
amount of System V shared memory (as an interlock to protect the data
directory) and allocate the rest as anonymous shared memory via mmap.
This will hopefully spare most users the hassle of adjusting operating
system parameters before being able to start PostgreSQL with a
reasonable value for shared_buffers.
There are a bunch of documentation updates needed here, and we might
need to adjust some of the HINT messages related to shared memory as
well. But it's not 100% clear how portable this is, so before we
write the documentation, let's give it a spin on the buildfarm and
see what turns red.
Tom Lane [Thu, 28 Jun 2012 03:18:30 +0000 (23:18 -0400)]
Make UtilityContainsQuery recurse until it finds a non-utility Query.
The callers of UtilityContainsQuery want it to return a non-utility Query
if it returns anything at all. However, since we made CREATE TABLE
AS/SELECT INTO into a utility command instead of a variant of SELECT,
a command like "EXPLAIN SELECT INTO" results in two nested utility
statements. So what we need UtilityContainsQuery to do is drill down
to the bottom non-utility Query.
I had thought of this possibility in setrefs.c, and fixed it there by
looping around the UtilityContainsQuery call; but overlooked that the call
sites in plancache.c have a similar issue. In those cases it's
notationally inconvenient to provide an external loop, so let's redefine
UtilityContainsQuery as recursing down to a non-utility Query instead.
Noted by Rushabh Lathia. This is a somewhat cleaned-up version of his
proposed patch.
Peter Eisentraut [Wed, 27 Jun 2012 18:21:18 +0000 (21:21 +0300)]
Fix install program detection
configure handles INSTALL as a substitution variable specially, and
apparently it gets confused when it's set to empty. Use INSTALL_
instead as a workaround to avoid the issue.
Peter Eisentraut [Wed, 27 Jun 2012 10:40:51 +0000 (13:40 +0300)]
Use system install program when available and usable
In a3176dac22c4cd14971e35119e245abee7649cb9 we switched to using
install-sh unconditionally, because the configure check
AC_PROG_INSTALL would pick up any random program named install, which
has caused failure reports
(http://archives.postgresql.org/pgsql-hackers/2001-03/msg00312.php).
Now the configure check is much improved and should avoid false
positives. It has also been shown that using a system install program
can significantly reduce "make install" times, so it's worth trying.
Tom Lane [Tue, 26 Jun 2012 18:36:25 +0000 (14:36 -0400)]
Cope with smaller-than-normal BLCKSZ setting in SPGiST indexes on text.
The original coding failed miserably for BLCKSZ of 4K or less, as reported
by Josh Kupershmidt. With the present design for text indexes, a given
inner tuple could have up to 256 labels (requiring either 3K or 4K bytes
depending on MAXALIGN), which means that we can't positively guarantee no
failures for smaller blocksizes. But we can at least make it behave sanely
so long as there are few enough labels to fit on a page. Considering that
btree is also more prone to "index tuple too large" failures when BLCKSZ is
small, it's not clear that we should expend more work than this on this
case.
Robert Haas [Tue, 26 Jun 2012 10:56:10 +0000 (06:56 -0400)]
Reduce use of heavyweight locking inside hash AM.
Avoid using LockPage(rel, 0, lockmode) to protect against changes to
the bucket mapping. Instead, an exclusive buffer content lock is now
viewed as sufficient permission to modify the metapage, and a shared
buffer content lock is used when such modifications need to be
prevented. This more relaxed locking regimen makes it possible that,
when we're busy getting a heavyweight bucket on the bucket we intend
to search or insert into, a bucket split might occur underneath us.
To compenate for that possibility, we use a loop-and-retry system:
release the metapage content lock, acquire the heavyweight lock on the
target bucket, and then reacquire the metapage content lock and check
that the bucket mapping has not changed. Normally it hasn't, and
we're done. But if by chance it has, we simply unlock the metapage,
release the heavyweight lock we acquired previously, lock the new
bucket, and loop around again. Even in the worst case we cannot loop
very many times here, since we don't split the same bucket again until
we've split all the other buckets, and 2^N gets big pretty fast.
This results in greatly improved concurrency, because we're
effectively replacing two lwlock acquire-and-release cycles in
exclusive mode (on one of the lock manager locks) with a single
acquire-and-release cycle in shared mode (on the metapage buffer
content lock). Testing shows that it's still not quite as good as
btree; for that, we'd probably have to find some way of getting rid
of the heavyweight bucket locks as well, which does not appear
straightforward.
Fix pg_upgrade, broken by the xlogid/segno -> 64-bit int refactoring.
The xlogid + segno representation of a particular WAL segment doesn't make
much sense in pg_resetxlog anymore, now that we don't use that anywhere
else. Use the WAL filename instead, since that's a convenient way to name a
particular WAL segment.
I did this partially for pg_resetxlog in the original xlogid/segno -> uint64
patch, but I neglected pg_upgrade and the docs. This should now be more
complete.
Tom Lane [Tue, 26 Jun 2012 01:20:24 +0000 (21:20 -0400)]
Make pg_dump emit more accurate dependency information.
While pg_dump has included dependency information in archive-format output
ever since 7.3, it never made any large effort to ensure that that
information was actually useful. In particular, in common situations where
dependency chains include objects that aren't separately emitted in the
dump, the dependencies shown for objects that were emitted would reference
the dump IDs of these un-dumped objects, leaving no clue about which other
objects the visible objects indirectly depend on. So far, parallel
pg_restore has managed to avoid tripping over this misfeature, but only
by dint of some crude hacks like not trusting dependency information in
the pre-data section of the archive.
It seems prudent to do something about this before it rises up to bite us,
so instead of emitting the "raw" dependencies of each dumped object,
recursively search for its actual dependencies among the subset of objects
that are being dumped.
Back-patch to 9.2, since that code hasn't yet diverged materially from
HEAD. At some point we might need to back-patch further, but right now
there are no known cases where this is actively necessary. (The one known
case, bug #6699, is fixed in a different way by my previous patch.) Since
this patch depends on 9.2 changes that made TOC entries be marked before
output commences as to whether they'll be dumped, back-patching further
would require additional surgery; and as of now there's no evidence that
it's worth the risk.
Tom Lane [Tue, 26 Jun 2012 01:19:10 +0000 (21:19 -0400)]
Improve pg_dump's dependency-sorting logic to enforce section dump order.
As of 9.2, with the --section option, it is very important that the concept
of "pre data", "data", and "post data" sections of the output be honored
strictly; else a dump divided into separate sectional files might be
unrestorable. However, the dependency-sorting logic knew nothing of
sections and would happily select output orderings that didn't fit that
structure. Doing so was mostly harmless before 9.2, but now we need to be
sure it doesn't do that. To fix, create dummy objects representing the
section boundaries and add dependencies between them and all the normal
objects. (This might sound expensive but it seems to only add a percent or
two to pg_dump's runtime.)
This also fixes a problem introduced in 9.1 by the feature that allows
incomplete GROUP BY lists when a primary key is given in GROUP BY.
That means that views can depend on primary key constraints. Previously,
pg_dump would deal with that by simply emitting the primary key constraint
before the view definition (and hence before the data section of the
output). That's bad enough for simple serial restores, where creating an
index before the data is loaded works, but is undesirable for speed
reasons. But it could lead to outright failure of parallel restores, as
seen in bug #6699 from Joe Van Dyk. That happened because pg_restore would
switch into parallel mode as soon as it reached the constraint, and then
very possibly would try to emit the view definition before the primary key
was committed (as a consequence of another bug that causes the view not to
be correctly marked as depending on the constraint). Adding the section
boundary constraints forces the dependency-sorting code to break the view
into separate table and rule declarations, allowing the rule, and hence the
primary key constraint it depends on, to revert to their intended location
in the post-data section. This also somewhat accidentally works around the
bogus-dependency-marking problem, because the rule will be correctly shown
as depending on the constraint, so parallel pg_restore will now do the
right thing. (We will fix the bogus-dependency problem for real in a
separate patch, but that patch is not easily back-portable to 9.1, so the
fact that this patch is enough to dodge the only known symptom is
fortunate.)
Back-patch to 9.1, except for the hunk that adds verification that the
finished archive TOC list is in correct section order; the place where
it was convenient to add that doesn't exist in 9.1.
Peter Eisentraut [Mon, 25 Jun 2012 18:25:26 +0000 (21:25 +0300)]
Unify calling conventions for postgres/postmaster sub-main functions
There was a wild mix of calling conventions: Some were declared to
return void and didn't return, some returned an int exit code, some
claimed to return an exit code, which the callers checked, but
actually never returned, and so on.
Now all of these functions are declared to return void and decorated
with attribute noreturn and don't return. That's easiest, and most
code already worked that way.
Robert Haas [Mon, 25 Jun 2012 16:14:43 +0000 (12:14 -0400)]
Remove sanity test in XRecOffIsValid.
Commit 061e7efb1b4c5b8a5d02122b7780531b8d5bf23d changed the rules
for splitting xlog records across pages, but neglected to update this
test. It's possible that there's some better action here than just
removing the test completely, but this at least appears to get some
of the things that are currently broken (like initdb on MacOS X)
working again.
Peter Eisentraut [Sun, 24 Jun 2012 22:51:46 +0000 (01:51 +0300)]
Replace int2/int4 in C code with int16/int32
The latter was already the dominant use, and it's preferable because
in C the convention is that intXX means XX bits. Therefore, allowing
mixed use of int2, int4, int8, int16, int32 is obviously confusing.
Remove the typedefs for int2 and int4 for now. They don't seem to be
widely used outside of the PostgreSQL source tree, and the few uses
can probably be cleaned up by the time this ships.
This simplifies code that needs to do arithmetic on XLogRecPtrs.
To avoid changing on-disk format of data pages, the LSN on data pages is
still stored in the old format. That should keep pg_upgrade happy. However,
we have XLogRecPtrs embedded in the control file, and in the structs that
are sent over the replication protocol, so this changes breaks compatibility
of pg_basebackup and server. I didn't do anything about this in this patch,
per discussion on -hackers, the right thing to do would to be to change the
replication protocol to be architecture-independent, so that you could use
a newer version of pg_receivexlog, for example, against an older server
version.
This saves a few bytes of WAL space, but the real motivation is to make it
predictable how much WAL space a record requires, as it no longer depends
on whether we need to waste the last few bytes at end of WAL page because
the header doesn't fit.
The total length field of WAL record, xl_tot_len, is moved to the beginning
of the WAL record header, so that it is still always found on the first page
where a WAL record begins.
Bump WAL version number again as this is an incompatible change.
Move WAL continuation record information to WAL page header.
The continuation record only contained one field, xl_rem_len, so it makes
things simpler to just include it in the WAL page header. This wastes four
bytes on pages that don't begin with a continuation from previos page, plus
four bytes on every page, because of padding.
The motivation of this is to make it easier to calculate how much space a
WAL record needs. Before this patch, it depended on how many page boundaries
the record crosses. The motivation of that, in turn, is to separate the
allocation of space in the WAL from the copying of the record data to the
allocated space. Keeping the calculation of space required simple helps to
keep the critical section of allocating the space from WAL short. But that's
not included in this patch yet.
Bump WAL version number again, as this is an incompatible change.
Don't waste the last segment of each 4GB logical log file.
The comments claimed that wasting the last segment made it easier to do
calculations with XLogRecPtrs, because you don't have problems representing
last-byte-position-plus-1 that way. In my experience, however, it only made
things more complicated, because the there was two ways to represent the
boundary at the beginning of a logical log file: logid = n+1 and xrecoff = 0,
or as xlogid = n and xrecoff = 4GB - XLOG_SEG_SIZE. Some functions were
picky about which representation was used.
Also, use a 64-bit segment number instead of the log/seg combination, to
point to a certain WAL segment. We assume that all platforms have a working
64-bit integer type nowadays.
This is an incompatible change in WAL format, so bumping WAL version number.
Tom Lane [Thu, 21 Jun 2012 21:26:07 +0000 (17:26 -0400)]
Fix memory leak in ARRAY(SELECT ...) subqueries.
Repeated execution of an uncorrelated ARRAY_SUBLINK sub-select (which
I think can only happen if the sub-select is embedded in a larger,
correlated subquery) would leak memory for the duration of the query,
due to not reclaiming the array generated in the previous execution.
Per bug #6698 from Armando Miraglia. Diagnosis and fix idea by Heikki,
patch itself by me.
This has been like this all along, so back-patch to all supported versions.