The other DDL operations that create an inheritance relationship were
checking for collation match already, but this one got missed.
Also fix comments that failed to mention collation checks.
This allows the usual rules for assigning a collation to a local variable
to be overridden. Per discussion, it seems appropriate to support this
rather than forcing all local variables to have the argument-derived
collation.
Fix crash when releasing duplicate entries in the encoding conversion cache
list, caused by releasing the current entry of the list being chased by
foreach(). We have a standard idiom for handling such cases, but this
loop wasn't using it.
This got broken in my recent rewrite of GUC assign hooks. Not sure how
I missed this when testing the modified code, but I did. Per report from
Peter.
For what seem entirely historical reasons, a bitmask "flags" argument was
recently added to reindex_relation without subsuming its existing boolean
argument into that bitmask. This seems a bit bizarre, so fold them
together.
This area was a few bricks shy of a load, and badly under-commented too.
We have to ensure that the generated targetlist entries for a set-operation
node expose the correct collation for each entry, since higher-level
processing expects the tlist to reflect the true ordering of the plan's
output.
This hackery wouldn't be necessary if SortGroupClause carried collation
info ... but making it do so would inject more pain in the parser than
would be saved here. Still, we might want to rethink that sometime.
The places that attempt to change pg_index.indcheckxmin during a reindexing
operation cannot be executed safely if pg_index itself is the subject of
the operation. This is the explanation for a couple of recent reports of
VACUUM FULL failing with
ERROR: duplicate key value violates unique constraint "pg_index_indexrelid_index"
DETAIL: Key (indexrelid)=(2678) already exists.
However, there isn't any real need to update indcheckxmin in such a
situation, if we assume that pg_index can never contain a truly broken HOT
chain. This assumption holds if new indexes are never created on it during
concurrent operations, which is something we don't consider safe for any
system catalog, not just pg_index. Accordingly, modify the code to not
manipulate indcheckxmin when reindexing any system catalog.
Back-patch to 8.3, where HOT was introduced. The known failure scenarios
involve 9.0-style VACUUM FULL, so there might not be any real risk before
9.0, but let's not assume that.
Although rowcount estimates really ought not be NaN, a bug elsewhere
could perhaps result in that, and that would cause Assert failure in
cost_mergejoin, which I believe to be the explanation for bug #5977 from
Anton Kuznetsov. Seems like a good idea to expend a couple more cycles
to prevent that, even though the real bug is elsewhere. Not back-patching,
though, because we don't encourage running production systems with
Asserts on.
apostrophes or dots. There isn't much hope of Microsoft fixing it any time
soon, it's been like that for ages, so we better work around it. So, map a
few common Windows locale names known to cause problems to aliases that work.
server-encoding, fall back to UTF-8. It happens at least with the Chinese
locale, which implies BIG5. This is safe, because on Windows all locales
are compatible with UTF-8.
The hash table is seq scanned at transaction end, to release all locks,
and making the hash table larger than necessary makes that slower. With
very simple queries, that overhead can amount to a few percent of the total
CPU time used.
At the moment, backend startup needs 6 locks, and a simple query with one
table and index needs 3 locks. 16 is enough for even quite complicated
transactions, and it will grow automatically if it fills up.
The lock level for adding a parent table is now ShareUpdateExclusiveLock;
see commit fbcf4b92aa. This comment didn't
get updated to match, but it doesn't seem important to mention this detail
here, so rather than updating it now, just take it out.
Instead of using slightly-too-clever heuristics to decide when we must
create a TOAST table, just check whether one is needed every time the
table is altered. Checking whether a toast table is needed is cheap
enough that we needn't worry about doing it on every ALTER TABLE command,
and the previous coding is apparently prone to accidental breakage:
commit 04e17bae50 broken ALTER TABLE ..
SET STORAGE, which moved some actions from AT_PASS_COL_ATTRS to
AT_PASS_MISC, and commit 6c57239985 broke
ALTER TABLE .. ADD COLUMN by changing the way that adding columns
recurses into child tables.
Noah Misch, with one comment change by me
When we are doing GEQO join planning, the current memory context is a
short-lived context that will be reset at the end of geqo_eval(). However,
the RelOptInfos for base relations are set up before that and then re-used
across many GEQO cycles. Hence, any code that modifies a baserel during
join planning has to be careful not to put pointers to the short-lived
context into the baserel struct. mark_dummy_rel got this wrong, leading to
easy-to-reproduce-once-you-know-how crashes in 8.4, as reported off-list by
Leo Carson of SDSC. Some improvements made in 9.0 make it difficult to
demonstrate the crash in 9.0 or HEAD; but there's no doubt that there's
still a risk factor here, so patch all branches that have the function.
(Note: 8.3 has a similar function, but it's only applied to joinrels and
thus is not a hazard.)
than on other platforms, and only IPv6 addresses are returned. Because of
those two issues, fall back to ioctl(SIOCGIFCONF) on HP/UX, so that it at
least compiles and finds IPv4 addresses. This function is currently only
used for interpreting samehost/samenet in pg_hba.conf, which isn't that
critical.
crash recovery, and throw an error if not. hubert depesz lubaczewski pointed
out that that situation also happens in the crash recovery following a
system crash that happens during an online backup.
We might want to do something smarter in 9.1, like put the check back for
backups taken with pg_basebackup, but that's for another patch.
Since collation is effectively an argument, not a property of the function,
FmgrInfo is really the wrong place for it; and this becomes critical in
cases where a cached FmgrInfo is used for varying purposes that might need
different collation settings. Fix by passing it in FunctionCallInfoData
instead. In particular this allows a clean fix for bug #5970 (record_cmp
not working). This requires touching a bit more code than the original
method, but nobody ever thought that collations would not be an invasive
patch...
The recent patch to remove gcc 4.6 warnings created some new ones, at
least on my rather old gcc version. Try to make everybody happy by
casting to "void" when we just want to discard the result.
In particular, if we don't have real ndistinct estimates for both sides,
fall back to assuming that half of the left-hand rows have join partners.
This is what was done in 8.2 and 8.3 (cf nulltestsel() in those versions).
It's pretty stupid but it won't lead us to think that an antijoin produces
no rows out, as seen in recent example from Uwe Schroeder.
If the referencing and referenced columns have different collations,
the parser will be unable to resolve which collation to use unless it's
helped out in this way. The effects are sometimes masked, if we end up
using a non-collation-sensitive plan; but if we do use a mergejoin
we'll see a failure, as recently noted by Robert Haas.
The SQL spec states that the referenced column's collation should be used
to resolve RI checks, so that's what we do. Note however that we currently
don't append a COLLATE clause when writing a query that examines only the
referencing column. If we ever support collations that have varying
notions of equality, that will have to be changed. For the moment, though,
it's preferable to leave it off so that we can use a normal index on the
referencing column.
This warning is new in gcc 4.6 and part of -Wall. This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.
This is necessary, not optional, now that ILIKE and regexes are collation
aware --- else we might derive a wrong comparison constant for index
optimized pattern matches.
entry's commitSeqNo to that of the old one being transferred, or take
the minimum commitSeqNo if it is merging two lock entries.
Also, CreatePredicateLock should initialize commitSeqNo for to
InvalidSerCommitSeqNo instead of to 0. (I don't think using 0 would
actually affect anything, but we should be consistent.)
I also added a couple of assertions I used to track this down: a
lock's commitSeqNo should never be zero, and it should be
InvalidSerCommitSeqNo if and only if the lock is not held by
OldCommittedSxact.
Dan Ports, to fix leak of predicate locks reported by YAMAMOTO Takashi.
This involves getting the character classification and case-folding
functions in the regex library to use the collations infrastructure.
Most of this work had been done already in connection with the upper/lower
and LIKE logic, so it was a simple matter of transposition.
While at it, split out these functions into a separate source file
regc_pg_locale.c, so that they can be correctly labeled with the Postgres
project's license rather than the Scriptics license. These functions are
100% Postgres-written code whereas what remains in regc_locale.c is still
mostly not ours, so lumping them both under the same copyright notice was
getting more and more misleading.
The original collation patch only fixed the multi-byte code path.
This change also ensures that ILIKE's idea of the case-folding rules
is exactly the same as str_tolower's.
Tweak the test so that it does not depend on the platform using ".utf8" as
the extension signifying that a locale uses UTF8 encoding. For the most
part this just requires using the abbreviated collation names "en_US" etc,
though I had to work a bit harder on the collation creation tests.
This opens the door to using the test on platforms that spell locales
differently, for example ".utf-8" or ".UTF-8". Also, the test is now
somewhat useful with server encodings other than UTF8; though depending on
which encoding is selected, different subsets of it will fail for lack of
character set support.
Remove crude hack that tried to propagate collation through a
function-returning-record, ie, from the function's arguments to individual
fields selected from its result record. That is just plain inconsistent,
because the function result is composite and cannot have a collation;
and there's no hope of making this kind of action-at-a-distance work
consistently. Adjust regression test cases that expected this to happen.
Meanwhile, the behavior of casting to a domain with a declared collation
stays the same as it was, since that seemed to be the consensus.
"Unusable" collations are those not matching the current database's
encoding. The former behavior inconsistently showed such collations
some of the time, depending on the details of the pattern argument.
Get rid of bogus collation test in match_special_index_operator (even for
ILIKE, the pattern match operator's collation doesn't matter here, and even
if it did the test was testing the wrong thing).
Fix broken looping logic in expand_indexqual_rowcompare.
Add collation check in match_clause_to_ordering_op.
Make naming and argument ordering more consistent; improve comments.
The previous coding worked only if ltproc->fn_collation was always either
DEFAULT_COLLATION_OID or a C-compatible locale. While that's true at the
moment, it wasn't documented (and in fact wasn't true when this code was
committed...). But it only takes a couple more lines to make its internal
caching behavior locale-aware, so let's do that.
Otherwise, the SLRU machinery can get confused and think that the SLRU
has wrapped around. Along the way, regardless of whether we're
truncating all of the SLRU or just some of it, flush pages after
truncating, rather than before.
Kevin Grittner
Honor index column's collation spec if there is one, don't go to the
expense of calling get_typcollation when we can reasonably assume that
all GIN storage types will use default collation, and be sure to set
a collation for the comparePartialFn too.
All the other fields of the constant are being extracted from the syscache
entry we already have, so handle collation similarly. (There don't seem
to be any other uses for the new function at the moment.)
Per discussion, the original behavior seems too noisy. But if things
are so broken that none of the locales reported by "locale -a" are usable,
that's probably worth warning about.
When a regular lock is held, SSI can use that in lieu of a predicate lock
to detect rw conflicts; but if the regular lock is being taken by a
subtransaction, we can't assume that it'll commit, so releasing the
parent transaction's lock in that case is a no-no.
Kevin Grittner
If we call hash_search() with HASH_ENTER, it will bail out rather than
return NULL, so it's redundant to check for NULL again in the caller.
Thus, in cases where we believe it's impossible for the hash table to run
out of slots anyway, we can simplify the code slightly.
On the flip side, in cases where it's theoretically possible to run out of
space, we don't want to rely on dynahash.c to throw an error; instead,
we pass HASH_ENTER_NULL and throw the error ourselves if a NULL comes
back, so that we can provide a more descriptive error message.
Kevin Grittner
Remove the hard-wired assumption that __mips__ (and only __mips__) lacks
dlopen in FreeBSD and OpenBSD. This assumption is outdated at least for
OpenBSD, as per report from an anonymous 9.1 tester. We can perfectly well
use HAVE_DLOPEN instead to decide which code to use.
Some other cosmetic adjustments to make freebsd.c, netbsd.c, and openbsd.c
exactly alike.
The original coding supposed that a dump TOC file could never contain lines
longer than 1K. The folly of that was exposed by a recent report from
Per-Olov Esgard. We only really need to see the first dozen or two bytes
of each line, since we're just trying to read off the numeric ID at the
start of the line; so there's no need for a particularly huge buffer.
What there is a need for is logic to not process continuation bufferloads.
Back-patch to all supported branches, since it's always been like this.
This is needed only in 9.1 because only 9.0 had this and no one is
upgrading from a 9.0 beta to 9.0 anymore. We basically don't backpatch
9.0 beta fixes at this point.
Previous patches took care of assorted places that call transformExpr from
outside the main parser, but I overlooked the fact that some places use
transformWhereClause as a shortcut for transformExpr + coerce_to_boolean.
In particular this broke collation-sensitive index WHERE clauses, as per
report from Thom Brown. Trigger WHEN and rule WHERE clauses too.
I'm not forcing initdb for this fix, but any affected indexes, triggers,
or rules will need to be dropped and recreated.
The previous functions of assign hooks are now split between check hooks
and assign hooks, where the former can fail but the latter shouldn't.
Aside from being conceptually clearer, this approach exposes the
"canonicalized" form of the variable value to guc.c without having to do
an actual assignment. And that lets us fix the problem recently noted by
Bernd Helmle that the auto-tune patch for wal_buffers resulted in bogus
log messages about "parameter "wal_buffers" cannot be changed without
restarting the server". There may be some speed advantage too, because
this design lets hook functions avoid re-parsing variable values when
restoring a previous state after a rollback (they can store a pre-parsed
representation of the value instead). This patch also resolves a
longstanding annoyance about custom error messages from variable assign
hooks: they should modify, not appear separately from, guc.c's own message
about "invalid parameter value".
When we release and reacquire SerializableXactHashLock, we must recheck
whether an R/W conflict still needs to be flagged, because it could have
changed under us in the meantime. And when we release the partition
lock, we must re-walk the list of predicate locks from the beginning,
because our pointer could get invalidated under us.
Bug report #5952 by Yamamoto Takashi. Patch by Kevin Grittner.
Also avoid hardcoding the current default state by giving it the name
"on" and replace with a meaningful name that reflects its behaviour.
Coding only, no change in behaviour.
This means one less thing to configure when setting up synchronous
replication, and also avoids some ambiguity around what the behavior
should be when the settings of these variables conflict.
Fujii Masao, with additional hacking by me.
The previous coding set attinhcount too high in some cases, resulting in
an undumpable, undroppable column. Per bug #5856, reported by Naoya
Anzai. See also commit 31b6fc06d8, which
fixes a similar bug in ALTER TABLE .. ADD CONSTRAINT.
Patch by Noah Misch.
If a smart shutdown occurs just as a child is starting up, and the
child subsequently becomes a walsender, there is a race condition:
the postmaster might count the exstant backends, determine that there
is one normal backend, and wait for it to die off. Had the walsender
transition already occurred before the postmaster counted, it would
have proceeded with the shutdown.
To fix this, have each child that transforms into a walsender kick
the postmaster just after doing so, so that the state machine is
certain to advance.
Fujii Masao
This would lead to leaking the PGconn structure after an error detected by
conninfo_array_parse(), as well as failing to return a useful error message
in such cases. Backpatch to 9.0 where the error was introduced.
Joseph Adams
This mostly involves making it work with the objectaddress.c framework,
which does most of the heavy lifting. In that vein, change
GetForeignDataWrapperOidByName to get_foreign_data_wrapper_oid and
GetForeignServerOidByName to get_foreign_server_oid, to match the
pattern we use for other object types.
Robert Haas and Shigeru Hanada
examining the head of predicate locks list. Also, fix the comment of
RemoveTargetIfNoLongerUsed, it was neglected when we changed the way update
chains are handled.
Kevin Grittner
archive recovery.
It's possible to restore an online backup without recovery.conf, by simply
copying all the necessary WAL files to pg_xlog. "pg_basebackup -x" does that
too. That's the use case where this cross-check is useful.
Backpatch to 9.0. We used to do this in earlier versins, but in 9.0 the code
was inadvertently changed so that the check is only performed after archive
recovery.
Fujii Masao.
than replication_timeout (a new GUC) milliseconds. The TCP timeout is often
too long, you want the master to notice a dead connection much sooner.
People complained about that in 9.0 too, but with synchronous replication
it's even more important to notice dead connections promptly.
Fujii Masao and Heikki Linnakangas
Feature F692 "Extended collation support" is now also supported. This
refers to allowing the COLLATE clause anywhere in a column or domain
definition instead of just directly after the type.
Also correct the name of the feature in accordance with the latest SQL
standard.
This can do various source code checks that are not appropriate for
either the build or the regression tests. Currently: duplicate_oids,
SGML syntax and tabs check, NLS syntax check.
Eventually we might be able to allow that, but it's not clear how many
places need to be fixed to prevent infinite recursion when there's a direct
or indirect inclusion of a rowtype in itself. One such place is
CheckAttributeType(), which will recurse to stack overflow in cases such as
those exhibited in bug #5950 from Alex Perepelica. If we were sure it was
the only such place, we could easily modify the code added by this patch to
stop the recursion without a complaint ... but it probably isn't the only
such place. Hence, throw error until such time as someone is excited
enough about this type of usage to put work into making it safe.
Back-patch as far as 8.3. 8.2 doesn't have the recursive call in
CheckAttributeType in the first place, so I see no need to add code there
in the absence of clear evidence of a problem elsewhere.
This fixes the gripe I made a few months ago about DO blocks getting
slower with repeated use. At least, it fixes it for the case where
the DO block isn't aborted by an error. We could try running
plpgsql_free_function_memory() even during error exit, but that seems
a bit scary since it makes a lot of presumptions about the data
structures being in good shape. It's probably reasonable to assume
that repeated failures of DO blocks isn't a performance-critical case.
I'm not sure these have any non-cosmetic implications, but I'm not sure
they don't, either. In particular, ensure the CaseTestExpr generated
by transformAssignmentIndirection to represent the base target column
carries the correct collation, because parse_collate.c won't fix that.
Tweak lsyscache.c API so that we can get the appropriate collation
without an extra syscache lookup.
In nearly all cases, the caller already knows the correct collation, and
in a number of places, the value the caller has handy is more correct than
the default for the type would be. (In particular, this patch makes it
significantly less likely that eval_const_expressions will result in
changing the exposed collation of an expression.) So an internal lookup
is both expensive and wrong.
Make plpgsql treat the input collation as a polymorphism variable, so
that we cache separate plans for each input collation that's used in a
particular session, as per recent discussion. Propagate the input
collation to all collatable input parameters.
I chose to also propagate the input collation to all declared variables of
collatable types, which is a bit more debatable but seems to be necessary
for non-astonishing behavior. (Copying a parameter into a separate local
variable shouldn't result in a change of behavior, for example.) There is
enough infrastructure here to support declaring a collation for each local
variable to override that default, but I thought we should wait to see what
the field demand is before adding such a feature.
In passing, remove exec_get_rec_fieldtype(), which wasn't used anywhere.
Documentation patch to follow.
It originally worked this way, but was changed by commit
a8a8a3e096, since which time it's been impossible
for walreceiver to ever send a reply with write_location and flush_location
set to different values.
Ensure that parameter symbols receive collation from the function's
resolved input collation, and fix inlining to behave properly.
BTW, this commit lays about 90% of the infrastructure needed to support
use of argument names in SQL functions. Parsing of parameters is now
done via the parser-hook infrastructure ... we'd just need to supply
a column-ref hook ...
Ensure that COLLATE at the top level of an index expression is treated the
same as a grammatically separate COLLATE. Fix bogus reverse-parsing logic
in pg_get_indexdef.
Change location LOG message so it works each time we pause, not
just for final pause.
Ensure that we pause only if we are in Hot Standby and can connect
to allow us to run resume function. This change supercedes the
code to override parameter recoveryPauseAtTarget to false if not
attempting to enter Hot Standby, which is now removed.
This is no longer necessary, and might result in a situation where the
configuration file is reloaded (and everything seems OK) but a subsequent
restart of the database fails.
Per an observation from Fujii Masao.
Startup process waited for cleanup lock but when hot_standby = off
the pid was not registered, so that the bgwriter would not wake
the waiting process as intended.
While putting such entries into pg_collation is harmless (since backends
will ignore entries that don't match the database encoding), it's also
useless.
pg_newlocale_from_collation does not have enough context to give an error
message that's even a little bit useful, so move the responsibility for
complaining up to its callers. Also, reword ERRCODE_INDETERMINATE_COLLATION
error messages in a less jargony, more message-style-guide-compliant
fashion.
This restores a parse error that was thrown (though only in the ORDER BY
case) by the original collation patch. I had removed it in my recent
revisions because it was thrown at a place where collations now haven't
been computed yet; but I thought of another way to handle it.
Throwing the error at parse time, rather than leaving it to be done at
runtime, is good because a syntax error pointer is helpful for localizing
the problem. We can reasonably assume that the comparison function for a
collatable datatype will complain if it doesn't have a collation to use.
Now the planner might choose to implement GROUP or DISTINCT via hashing,
in which case no runtime error would actually occur, but it seems better
to throw error consistently rather than let the error depend on what the
planner chooses to do. Another possible objection is that the user might
specify a nondefault sort operator that doesn't care about collation
... but that's surely an uncommon usage, and it wouldn't hurt him to throw
in a COLLATE clause anyway. This change also makes the ORDER BY/GROUP
BY/DISTINCT case more consistent with the UNION/INTERSECT/EXCEPT case,
which was already coded to throw this error even though the same objections
could be raised there.
Opening a catcache's index could require reading from that cache's own
catalog, which of course would acquire AccessShareLock on the catalog.
So the original coding here risks locking index before heap, which could
deadlock against another backend trying to get exclusive locks in the
normal order. Because InitCatCachePhase2 is only called when a backend
has to start up without a relcache init file, the deadlock was seldom seen
in the field. (And by the same token, there's no need to worry about any
performance disadvantage; so not much point in trying to distinguish
exactly which catalogs have the risk.)
Bug report, diagnosis, and patch by Nikhil Sontakke. Additional commentary
by me. Back-patch to all supported branches.
Instead of playing cute games with pathkeys, just build a direct
representation of the intended sub-select, and feed it through
query_planner to get a Path for the index access. This is a bit slower
than 9.1's previous method, since we'll duplicate most of the overhead of
query_planner; but since the whole optimization only applies to rather
simple single-table queries, that probably won't be much of a problem in
practice. The advantage is that we get to do the right thing when there's
a partial index that needs the implicit IS NOT NULL clause to be usable.
Also, although this makes planagg.c be a bit more closely tied to the
ordering of operations in grouping_planner, we can get rid of some coupling
to lower-level parts of the planner. Per complaint from Marti Raudsepp.
ensure that they use different checkpoints as the starting point. We use
the checkpoint redo location as a unique identifier for the base backup in
the end-of-backup record, and in the backup history file name.
Bug spotted by Fujii Masao.
The local variable "sock" can be unused depending on compilation flags.
But there seems no particular need for it, since the kernel calls can
just as easily say port->sock instead.
Install just one instance of the "C" and "POSIX" collations into
pg_collation, rather than one per encoding. Make these instances exist
and do something useful even in machines without locale_t support: to wit,
it's now possible to force comparisons and case-folding functions to use C
locale in an otherwise non-C database, whether or not the platform has
support for using any additional collations.
Fix up severely broken upper/lower/initcap functions, too: the C/POSIX
fastpath now does what it is supposed to, and non-default collations are
handled correctly in single-byte database encodings.
Merge the two separate collation hashtables that were being maintained in
pg_locale.c, and be more wary of the possibility that we fail partway
through filling a cache entry.
All expression nodes now have an explicit output-collation field, unless
they are known to only return a noncollatable data type (such as boolean
or record). Also, nodes that can invoke collation-aware functions store
a separate field that is the collation value to pass to the function.
This avoids confusion that arises when a function has collatable inputs
and noncollatable output type, or vice versa.
Also, replace the parser's on-the-fly collation assignment method with
a post-pass over the completed expression tree. This allows us to use
a more complex (and hopefully more nearly spec-compliant) assignment
rule without paying for it in extra storage in every expression node.
Fix assorted bugs in the planner's handling of collations by making
collation one of the defining properties of an EquivalenceClass and
by converting CollateExprs into discardable RelabelType nodes during
expression preprocessing.
This removes an overloading of two authentication options where
one is very secure (peer) and one is often insecure (ident). Peer
is also the name used in libpq from 9.1 to specify the same type
of authentication.
Also make initdb select peer for local connections when ident is
chosen, and ident for TCP connections when peer is chosen.
ident keyword in pg_hba.conf is still accepted and maps to peer
authentication.
When adding an inheritance parent to a table, an AccessShareLock on the
parent isn't strong enough to prevent trouble, so take
ShareUpdateExclusiveLock instead. Since this is a behavior change,
albeit a fairly unobtrusive one, and since we have only one report
from the field, no back-patch.
Report by Jon Nelson, analysis by Alvaro Herrera, fix by me.
This is advantageous because the BG writer is alive until much later in
the shutdown sequence than WAL writer; we want to make sure that it's
possible to shut off synchronous replication during a smart shutdown,
else it might not be possible to complete the shutdown at all.
Per very reasonable gripes from Fujii Masao and Simon Riggs.
The last version in which these options were documented is now EOL, so
it's time to get rid of them for real. We now use GNU-style long
options instead.
The maximum value of deadlock_timeout, max_standby_archive_delay,
max_standby_streaming_delay, log_min_duration_statement, and
log_autovacuum_min_duration was INT_MAX/1000 milliseconds, which is
about 35min, which is too short for some practical uses. Raise the
maximum value to INT_MAX; the code that uses the parameters already
supports that just fine.
1. Don't ignore query cancel interrupts. Instead, if the user asks to
cancel the query after we've already committed it, but before it's on
the standby, just emit a warning and let the COMMIT finish.
2. Don't ignore die interrupts (pg_terminate_backend or fast shutdown).
Instead, emit a warning message and close the connection without
acknowledging the commit. Other backends will still see the effect of
the commit, but there's no getting around that; it's too late to abort
at this point, and ignoring die interrupts altogether doesn't seem like
a good idea.
3. If synchronous_standby_names becomes empty, wake up all backends
waiting for synchronous replication to complete. Without this, someone
attempting to shut synchronous replication off could easily wedge the
entire system instead.
4. Avoid depending on the assumption that if a walsender updates
MyProc->syncRepState, we'll see the change even if we read it without
holding the lock. The window for this appears to be quite narrow (and
probably doesn't exist at all on machines with strong memory ordering)
but protecting against it is practically free, so do that.
5. Remove useless state SYNC_REP_MUST_DISCONNECT, which isn't needed and
doesn't actually do anything.
There's still some further work needed here to make the behavior of fast
shutdown plausible, but that looks complex, so I'm leaving it for a
separate commit. Review by Fujii Masao.
This has been broken for years, and I'm not sure why it has not been
noticed before, but now a very modern Cygwin breaks on it, and the fix
is clearly correct. Backpatching to all live branches.
This patch causes unknown-type Consts to be coerced to the resolved output
type of the set operation at parse time. Formerly such Consts were left
alone until late in the planning stage. The disadvantage of that approach
is that it disables some optimizations, because the planner sees the set-op
leaf query as having different output column types than the overall set-op.
We saw an example of that in a recent performance gripe from Claudio
Freire.
Fixing such a Const requires scribbling on the leaf query in
transformSetOperationTree, but that should be all right since if the leaf
query's semantics depended on that output column, it would already have
resolved the unknown to something else.
Most of the bulk of this patch is a simple adjustment of
transformSetOperationTree's API so that upper levels can get at the
TargetEntry containing a Const to be replaced: it now returns a list of
TargetEntries, instead of just the bare expressions.
This was required in pre-8.4 versions to allow the specification of
"ident sameuser", but sameuser is no longer required. It could be extended
to allow all parameters in the future, but should then apply to all
methods and not just ident.
We have a test that verifies that max(anyarray) will cope if the array
column elements aren't all the same array type. However, it's now possible
for that to produce a collation-related error message instead of the
expected one, if the first two column elements happen to be of the same
type and it's one that expects to be given collation info. Tweak the test
to ensure this doesn't happen. Per buildfarm member pika.
While this will give wrong answers when estimating selectivity for a
comparison operator that's using a non-default collation, the estimation
error probably won't be large; and anyway the former approach created
estimation errors of its own by trying to use a histogram that might have
been computed with some other collation. So we'll adopt this simplified
approach for now and perhaps improve it sometime in the future.
This patch incorporates changes from Andres Freund to make sure that
selfuncs.c passes a valid collation OID to any datatype-specific function
it calls, in case that function wants collation information. Said OID will
now always be DEFAULT_COLLATION_OID, but at least we won't get errors.
Add dummy returns before every potential division-by-zero in int8.c,
because apparently further "improvements" in gcc's optimizer have
enabled it to break functions that weren't broken before.
Aurelien Jarno, via Martin Pitt
CollateClause is now used only in raw grammar output, and CollateExpr after
parse analysis. This is for clarity and to avoid carrying collation names
in post-analysis parse trees: that's both wasteful and possibly misleading,
since the collation's name could be changed while the parsetree still
exists.
Also, clean up assorted infelicities and omissions in processing of the
node type.
Use collencoding = -1 to represent such a collation in pg_collation.
We need this to make the "default" entry work sanely, and a later
patch will fix the C/POSIX entries to be represented this way instead
of duplicating them across all encodings. All lookup operations now
search first for an entry that's database-encoding-specific, and then
for the same name with collencoding = -1.
Also some incidental code cleanup in collationcmds.c and pg_collation.c.
variable hiding. A constant is not a variable. It worked in most cases by
accident, because we add constants to the global list of variables (why?),
but float constants like 1.23 were interpreted as struct field references,
and not found.
Backpatch to 9.0, where the test for variable hiding was added.
Including collation in the behavior of that function promotes a world view
we do not want. Moreover, it was producing the wrong behavior for pg_dump
anyway: what we want is to dump a COLLATE clause on attributes whose
attcollation is different from the underlying type, and likewise for
domains, and the function cannot do that for us. Doing it the hard way
in pg_dump is a bit more tedious but produces more correct output.
In passing, fix initdb so that the initial entry in pg_collation is
properly pinned. It was droppable before :-(
It's not a good idea to kill the postmaster just because someone muffs
this, and it's not consistent with what we do for other, similar GUCs.
Fujii Masao, with a bit more hacking by me
SyncRepRequested() must check not only the value of the
synchronous_replication GUC but also whether max_wal_senders > 0.
Otherwise, we might end up waiting for sync rep even when there's no
possibility of a standby ever managing to connect. There are some
existing cross-checks to prevent this, but they're not quite sufficient:
the user can start the server with max_wal_senders=0,
synchronous_standby_names='', and synchronous_replication=off and then
subsequent make synchronous_standby_names not empty using pg_ctl reload,
and then SET synchronous_standby=on, leading to an indefinite hang.
Along the way, rename the global variable for the synchronous_replication
GUC to match the name of the GUC itself, for clarity.
Report by Fujii Masao, though I didn't use his patch.
In earlier versions of the sync rep patch, waiters removed themselves from
the queue, but now walsender removes them before doing the wakeup.
Report by Fujii Masao.
Tom Lane pointed out that it was giving a warning: "-s option given but
default rule can be matched". That was because there was no rule to handle
newline in a quoted string. I made that throw an error.
Also, line number tracking was broken, giving incorrect line number on
error. Fixed that too.
At least two recent commits have apparently imagined that a comment in
a Makefile stating that something would be included in the distribution
tarball was sufficient to make it so. They hadn't bothered to hook
into the upper maintainer-clean targets either. Per bug #5923 from
Charles Johnson, in which it emerged that the 9.1alpha4 tarballs are
short a few files that should be there.
The initial collations patch treated a COLLATE spec as part of a TypeName,
following what can only be described as brain fade on the part of the SQL
committee. It's a lot more reasonable to treat COLLATE as a syntactically
separate object, so that it can be added in only the productions where it
actually belongs, rather than needing to reject it in a boatload of places
where it doesn't belong (something the original patch mostly failed to do).
In addition this change lets us meet the spec's requirement to allow
COLLATE anywhere in the clauses of a ColumnDef, and it avoids unfriendly
behavior for constructs such as "foo::type COLLATE collation".
To do this, pull collation information out of TypeName and put it in
ColumnDef instead, thus reverting most of the collation-related changes in
parse_type.c's API. I made one additional structural change, which was to
use a ColumnDef as an intermediate node in AT_AlterColumnType AlterTableCmd
nodes. This provides enough room to get rid of the "transform" wart in
AlterTableCmd too, since the ColumnDef can carry the USING expression
easily enough.
Also fix some other minor bugs that have crept in in the same areas,
like failure to copy recently-added fields of ColumnDef in copyfuncs.c.
While at it, document the formerly secret ability to specify a collation
in ALTER TABLE ALTER COLUMN TYPE, ALTER TYPE ADD ATTRIBUTE, and
ALTER TYPE ALTER ATTRIBUTE TYPE; and correct some misstatements about
what the default collation selection will be when COLLATE is omitted.
BTW, the three-parameter form of format_type() should go away too,
since it just contributes to the confusion in this area; but I'll do
that in a separate patch.
Formerly, any member of a role could change the role's comment, as of
course could superusers; but holders of CREATEROLE privilege could not,
unless they were also members. This led to the odd situation that a
CREATEROLE holder could create a role but then could not comment on it.
It also seems a bit dubious to let an unprivileged user change his own
comment, let alone those of group roles he belongs to. So, change the
rule to be "you must be superuser to comment on a superuser role, or
hold CREATEROLE to comment on non-superuser roles". This is the same
as the privilege check for creating/dropping roles, and thus fits much
better with the rule for other object types, namely that only the owner
of an object can comment on it.
In passing, clean up the documentation for COMMENT a little bit.
Per complaint from Owen Jacobson and subsequent discussion.
In addition to the
all-foo-recurse: all-bar-recurse
dependencies that constraint the order of the rule execution, we need
install-foo-recurse: install-bar-recurse
dependencies in case one runs make install without a make all first,
as some people apparently do.
We really need an automated check for this ... and did VALIDATE really
need to become a keyword at all, rather than picking some other syntax
using existing keywords?
race condition where SummarizeOldestCommittedSxact() is called even though
another backend already cleared out all finished sxact entries. That's OK,
RegisterSerializableTransactionInt() can just retry getting a news xact
slot from the available-list when that happens.
Reported by YAMAMOTO Takashi, bug #5918.
contains newly-inserted tuples that according to our OldestXmin are not
yet visible to everyone. The value returned by GetOldestXmin() is conservative,
and it can move backwards on repeated calls, so if we see that contradiction
between the PD_ALL_VISIBLE flag and status of tuples on the page, we have to
assume it's because an earlier vacuum calculated a higher OldestXmin value,
and all the tuples really are visible to everyone.
We have received several reports of this bug, with the "PD_ALL_VISIBLE flag
was incorrectly set in relation ..." warning appearing in logs. We were
finally able to hunt it down with David Gould's help to run extra diagnostics
in an environment where this happened frequently.
Also reword the warning, per Robert Haas' suggestion, to not imply that the
PD_ALL_VISIBLE flag is necessarily at fault, as it might also be a symptom
of corruption on a tuple header.
Backpatch to 8.4, where the PD_ALL_VISIBLE flag was introduced.
than doing it aggressively whenever the tail-XID pointer is advanced, because
this way we don't need to do it while holding SerializableXactHashLock.
This also fixes bug #5915 spotted by YAMAMOTO Takashi, and removes an
obsolete comment spotted by Kevin Grittner.
This improves reporting, as the error string now includes the actual
Python exception. As a side effect, this no longer sets the errcode to
ERRCODE_DATA_EXCEPTION, which might be considered a feature, as it's
not documented and not clear why iterator errors should be treated
differently.
Jan Urbański
periodically rescan the archive for new timelines, while waiting for new WAL
segments to arrive. This allows you to set up a standby server that follows
the TLI change if another standby server is promoted to master. Before this,
you had to restart the standby server to make it notice the new timeline.
This patch only scans the archive for TLI changes, it won't follow a TLI
change in streaming replication. That is much needed too, but it would be a
much bigger patch than I dare to sneak in this late in the release cycle.
There was discussion on improving the sanity checking of the WAL segments so
that the system would notice more reliably if the new timeline isn't an
ancestor of the current one, but that is not included in this patch.
Reviewed by Fujii Masao.
Seen with an older gcc version. I'm not sure these represent any real
risk factor, but still a bit scary. Anyway we have lots of other
volatile-marked variables in this code, so a couple more won't hurt.
If a standby is broadcasting reply messages and we have named
one or more standbys in synchronous_standby_names then allow
users who set synchronous_replication to wait for commit, which
then provides strict data integrity guarantees. Design avoids
sending and receiving transaction state information so minimises
bookkeeping overheads. We synchronize with the highest priority
standby that is connected and ready to synchronize. Other standbys
can be defined to takeover in case of standby failure.
This version has very strict behaviour; more relaxed options
may be added at a later date.
Simon Riggs and Fujii Masao, with reviews by Yeb Havinga, Jaime
Casanova, Heikki Linnakangas and Robert Haas, plus the assistance
of many other design reviewers.
Since this field is after a variable-length field, it can't simply be
accessed via the C struct for pg_index. Fortunately, the relcache already
did the dirty work of pulling the information out to where it can be
accessed easily, so this is a one-line fix.
Andres Freund
The original scheme for this was to symlink plpython.$DLSUFFIX to
plpython2.$DLSUFFIX, but that doesn't work on Windows, and only
accidentally failed to fail because of the way that CREATE LANGUAGE created
or didn't create new C functions. My changes of yesterday exposed the
weakness of that approach. To fix, get rid of the symlink and make
pg_pltemplate show what's really going on.
In createlang this is a one-line change. In droplang there's a whole
lot of cruft that can be discarded since the extension mechanism now
manages removal of the language's support functions.
Also, add deprecation notices to these two programs' reference pages,
since per discussion we may toss them overboard altogether in a release
or two.
This mostly just involves creating control, install, and
update-from-unpackaged scripts for them. However, I had to adjust plperl
and plpython to not share the same support functions between variants,
because we can't put the same function into multiple extensions.
catversion bump forced due to new contents of pg_pltemplate, and because
initdb now installs plpgsql as an extension not a bare language.
Add support for regression testing these as extensions not bare
languages.
Fix a couple of other issues that popped up while testing this: my initial
hack at pg_dump binary-upgrade support didn't work right, and we don't want
an extra schema permissions test after all.
Documentation changes still to come, but I'm committing now to see
whether the MSVC build scripts need work (likely they do).
It is possible that an expression ends up with a collatable type but
without a collation. CREATE TABLE AS could then create a table based
on that. But such a column cannot be dumped with valid SQL syntax, so
we disallow creating such a column.
per test report from Noah Misch
Remove the unconditional superuser permissions check in CREATE EXTENSION,
and instead define a "superuser" extension property, which when false
(not the default) skips the superuser permissions check. In this case
the calling user only needs enough permissions to execute the commands
in the extension's installation script. The superuser property is also
enforced in the same way for ALTER EXTENSION UPDATE cases.
In other ALTER EXTENSION cases and DROP EXTENSION, test ownership of
the extension rather than superuserness. ALTER EXTENSION ADD/DROP needs
to insist on ownership of the target object as well; to do that without
duplicating code, refactor comment.c's big switch for permissions checks
into a separate function in objectaddress.c.
I also removed the superuserness checks in pg_available_extensions and
related functions; there's no strong reason why everybody shouldn't
be able to see that info.
Also invent an IF NOT EXISTS variant of CREATE EXTENSION, and use that
in pg_dump, so that dumps won't fail for installed-by-default extensions.
We don't have any of those yet, but we will soon.
This is all per discussion of wrapping the standard procedural languages
into extensions. I'll make those changes in a separate commit; this is
just putting the core infrastructure in place.
Instead, just act as though the certificate file(s) are not present.
There is only one case where this need be a hard failure condition: when
sslmode is verify-ca or verify-full, not having a root cert file is an
error. Change the logic so that we complain only in that case, and
otherwise fall through cleanly. This is how it used to behave pre-9.0,
but my patch 4ed4b6c54e of 2010-05-26 broke
the case. Per report from Christian Kastner.
Instead of manually maintaining the "implementation of XXX operator"
comments in pg_proc.h, delete all those entries and let initdb create
them via a join. To let initdb figure out which name to use when there
is a conflict, change the comments for deprecated operators to say they
are deprecated --- which seems like a good thing to do anyway.
This works around the problem noted by Yamamoto Takashi in bug #5906,
that there were code paths whereby we could reach AtCleanup_Portals
with a portal's cleanup hook still unexecuted. The changes I made
a few days ago were intended to prevent that from happening, and
I think that on balance it's still a good thing to avoid, so I don't
want to remove the Assert in AtCleanup_Portals. Hence do this instead.
Historically, we've not had separate comments for built-in pg_operator
entries, but relied on the comments for the underlying functions. The
trouble with this approach is that there isn't much of anything to suggest
to users that they'd be better off using the operators instead. So, move
all the relevant comments into pg_operator, and give each underlying
function a comment that just says "implementation of XXX operator".
There are only about half a dozen cases where it seems reasonable to use
the underlying function interchangeably with the operator; in these cases
I left the same comment in place on the function as on the operator.
While at it, establish a policy that every built-in function and operator
entry should have a comment: there are now queries in the opr_sanity
regression test that will complain if one doesn't. This only required
adding a dozen or two more entries than would have been there anyway.
I also spent some time trying to eliminate gratuitous inconsistencies in
the style of the comments, though it's hopeless to suppose that more won't
creep in soon enough.
Per my proposal of 2010-10-15.
it a lot more useful for determining which standby is most up-to-date,
for example. There was long discussions on whether overwriting existing
existing WAL makes sense to begin with, and whether we should do some more
extensive variable renaming, but this change nevertheless seems quite
uncontroversial.
Fujii Masao, reviewed by Jeff Janes, Robert Haas, Stephen Frost.
Change the way UPDATEs are handled. Instead of maintaining a chain of
tuple-level locks in shared memory, copy any existing locks on the old
tuple to the new tuple at UPDATE. Any existing page-level lock needs to
be duplicated too, as a lock on the new tuple. That was neglected
previously.
Store xmin on tuple-level predicate locks, to distinguish a lock on an old
already-recycled tuple from a new tuple at the same physical location.
Failure to distinguish them caused loops in the tuple-lock chains, as
reported by YAMAMOTO Takashi. Although we don't use the chain representation
of UPDATEs anymore, it seems like a good idea to store the xmin to avoid
some false positives if no other reason.
CheckSingleTargetForConflictsIn now correctly handles the case where a lock
that's being held is not reflected in the local lock table. That happens
if another backend acquires a lock on our behalf due to an UPDATE or a page
split.
PredicateLockPageCombine now retains locks for the page that is being
removed, rather than removing them. This prevents a potentially dangerous
false-positive inconsistency where the local lock table believes that a lock
is held, but it is actually not.
Dan Ports and Kevin Grittner
Per discussion, this seems important for plans involving writable CTEs,
since there can now be more than one ModifyTable node in the plan.
To retain the same formatting as for target tables of scan nodes, we
show only one target table, which will be the parent table in case of
an UPDATE or DELETE on an inheritance tree. Individual child tables
can be determined by inspecting the child plan trees if needed.
Without this patch, when wal_receiver_status_interval=0, indicating that no
status messages should be sent, Hot Standby feedback messages are instead sent
extremely frequently.
Fujii Masao, with documentation changes by me.
With this patch, portals, SQL functions, and SPI all agree that there
should be only a CommandCounterIncrement between the queries that are
generated from a single SQL command by rule expansion. Fetching a whole
new snapshot now happens only between original queries. This is equivalent
to the existing behavior of EXPLAIN ANALYZE, and it was judged to be the
best choice since it eliminates one source of concurrency hazards for
rules. The patch should also make things marginally faster by reducing the
number of snapshot push/pop operations.
The patch removes pg_parse_and_rewrite(), which is no longer used anywhere.
There was considerable discussion about more aggressive refactoring of the
query-processing functions exported by postgres.c, but for the moment
nothing more has been done there.
I also took the opportunity to refactor snapmgr.c's API slightly: the
former PushUpdatedSnapshot() has been split into two functions.
Marko Tiikkaja, reviewed by Steve Singer and Tom Lane
This provides a separate exception class for each error code that the
backend defines, as well as the ability to get the SQLSTATE from the
exception object.
Jan Urbański, reviewed by Steve Singer
Adds a context manager, obtainable by plpy.subtransaction(), to run a
group of statements in a subtransaction.
Jan Urbański, reviewed by Steve Singer, additional scribbling by me
We don't have complete expected coverage for Python 2.2 anyway, so it
doesn't seem worth keeping this one around that no one appears to be
updating anyway. Visual inspection of the differences ought to be
good enough for those few who care about this obsolete Python version.
The originally committed patch for modifying CTEs didn't interact well
with EXPLAIN, as noted by myself, and also had corner-case problems with
triggers, as noted by Dean Rasheed. Those problems show it is really not
practical for ExecutorEnd to call any user-defined code; so split the
cleanup duties out into a new function ExecutorFinish, which must be called
between the last ExecutorRun call and ExecutorEnd. Some Asserts have been
added to these functions to help verify correct usage.
It is no longer necessary for callers of the executor to call
AfterTriggerBeginQuery/AfterTriggerEndQuery for themselves, as this is now
done by ExecutorStart/ExecutorFinish respectively. If you really need to
suppress that and do it for yourself, pass EXEC_FLAG_SKIP_TRIGGERS to
ExecutorStart.
Also, refactor portal commit processing to allow for the possibility that
PortalDrop will invoke user-defined code. I think this is not actually
necessary just yet, since the portal-execution-strategy logic forces any
non-pure-SELECT query to be run to completion before we will consider
committing. But it seems like good future-proofing.
This allows functions with multiple OUT parameters returning both one
or multiple records (RECORD or SETOF RECORD).
Jan Urbański, reviewed by Hitoshi Harada
We need ExecutorEnd to run the ModifyTable nodes to completion in
reverse order of initialization, not forward order. Easily done
by constructing the list back-to-front.
This patch implements data-modifying WITH queries according to the
semantics that the updates all happen with the same command counter value,
and in an unspecified order. Therefore one WITH clause can't see the
effects of another, nor can the outer query see the effects other than
through the RETURNING values. And attempts to do conflicting updates will
have unpredictable results. We'll need to document all that.
This commit just fixes the code; documentation updates are waiting on
author.
Marko Tiikkaja and Hitoshi Harada
Emit a log message when creating a named restore point, and improve
documentation for pg_create_restore_point().
Euler Taveira de Oliveira, per suggestions from Thom Brown, with some
additional wordsmithing by me.
- ALTER FOREIGN DATA WRAPPER with HANDLER
- ALTER TABLE VALIDATE CONSTRAINT
- ALTER TYPE ADD VALUE
- COPY with ENCODING and FORCE NOT NULL
- CREATE FOREIGN DATA WRAPPER with HANDLER
- CREATE TRIGGER ... INSTEAD OF
The recent additions for FDW support required checking foreign-table-ness
in several places in the parse/plan chain. While it's not clear whether
that would really result in a noticeable slowdown, it seems best to avoid
any performance risk by keeping a copy of the relation's relkind in
RangeTblEntry. That might have some other uses later, anyway.
Per discussion.
Add functions plpy.quote_ident, plpy.quote_literal,
plpy.quote_nullable, which wrap the equivalent SQL functions.
To be able to propagate char * constness properly, make the argument
of quote_literal_cstr() const char *. This also makes it more
consistent with quote_identifier().
Jan Urbański, reviewed by Hitoshi Harada, some refinements by Peter
Eisentraut
"SELECT ... INTO UNLOGGED tabname" works, but wasn't documented; CREATE
UNLOGGED SEQUENCE and CREATE UNLOGGED VIEW failed an assertion, instead
of throwing a sensible error.
Latter issue reported by Itagaki Takahiro; patch review by Tom Lane.
void_send is useful for the same reason that void_out doesn't throw error,
namely that someone might do "select void_returning_func(...)" from a
client that prefers to operate in binary mode. The void_recv function may
or may not have any practical use, but we provide it for symmetry.
Radosław Smogura
This was a leftover from the pre-8.1 design of junkfilters. It doesn't
seem to have any reason to live, since it's merely a combination of two
easy function calls, and not a well-designed combination at that (it
encourages callers to leak the result tuple).
ExecUpdate checked for whether ExecBRUpdateTriggers had returned a new
tuple value by seeing if the returned tuple was pointer-equal to the old
one. But the "old one" was in estate->es_junkFilter's result slot, which
would be scribbled on if we had done an EvalPlanQual update in response to
a concurrent update of the target tuple; therefore we were comparing a
dangling pointer to a live one. Given the right set of circumstances we
could get a false match, resulting in not forcing the tuple to be stored in
the slot we thought it was stored in. In the case reported by Maxim Boguk
in bug #5798, this led to "cannot extract system attribute from virtual
tuple" failures when trying to do "RETURNING ctid". I believe there is a
very-low-probability chance of more serious errors, such as generating
incorrect index entries based on the original rather than the
trigger-modified version of the row.
In HEAD, change all of ExecBRInsertTriggers, ExecIRInsertTriggers,
ExecBRUpdateTriggers, and ExecIRUpdateTriggers so that they continue to
have similar APIs. In the back branches I just changed
ExecBRUpdateTriggers, since there is no bug in the ExecBRInsertTriggers
case.
File encodings can be specified separately from client encoding.
If not specified, client encoding is used for backward compatibility.
Cases when the encoding doesn't match client encoding are slower
than matched cases because we don't have conversion procs for other
encodings. Performance improvement would be be a future work.
Original patch by Hitoshi Harada, and modified by me.
This is both very useful in its own right, and an important test case
for the core FDW support.
This commit includes a small refactoring of copy.c to expose its option
checking code as a separately callable function. The original patch
submission duplicated hundreds of lines of that code, which seemed pretty
unmaintainable.
Shigeru Hanada, reviewed by Itagaki Takahiro and Tom Lane
This commit provides the core code and documentation needed. A contrib
module test case will follow shortly.
Shigeru Hanada, Jan Urbanski, Heikki Linnakangas