This is the proper fix for bug #6082 about
pg_stat_reset_shared(NULL) causing a crash, and it reverts
commit 79aa44536f on head.
The workaround of throwing an error from inside the function is
left on backbranches (including 9.1) since this change requires
a new initdb.
This means that they can initially be added to a large existing table
without checking its initial contents, but new tuples must comply to
them; a separate pass invoked by ALTER TABLE / VALIDATE can verify
existing data and ensure it complies with the constraint, at which point
it is marked validated and becomes a normal part of the table ecosystem.
An non-validated CHECK constraint is ignored in the planner for
constraint_exclusion purposes; when validated, cached plans are
recomputed so that partitioning starts working right away.
This patch also enables domains to have unvalidated CHECK constraints
attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT
VALID, which can later be validated with ALTER DOMAIN / VALIDATE
CONSTRAINT.
Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various
reviews, and Robert Hass for documentation wording improvement
suggestions.
This patch was sponsored by Enova Financial.
Such a condition is unsatisfiable in combination with any other type of
btree-indexable condition (since we assume btree operators are always
strict). 8.3 and 8.4 had an explicit test for this, which I removed in
commit 29c4ad9829, mistakenly thinking that
the case would be subsumed by the more general handling of IS (NOT) NULL
added in that patch. Put it back, and improve the comments about it, and
add a regression test case.
Per bug #6079 from Renat Nasyrov, and analysis by Dean Rasheed.
more consistent that way, since all the other PredicateLock* calls are
made in various heapam.c and index AM functions. The call in nodeSeqscan.c
was unnecessarily aggressive anyway, there's no need to try to lock the
relation every time a tuple is fetched, it's enough to do it once.
This has the user-visible effect that if a seq scan is initialized in the
executor, but never executed, we now acquire the predicate lock on the heap
relation anyway. We could avoid that by taking the lock on the first
heap_getnext() call instead, but it doesn't seem worth the trouble given
that it feels more natural to do it in heap_beginscan().
Also, remove the retail PredicateLockTuple() calls from heap_getnext(). In
a seqscan, started with heap_begin(), we're holding a whole-relation
predicate lock on the heap so there's no need to lock the tuples
individually.
Kevin Grittner and me
XLOG_XACT_COMMIT_COMPACT leaves out invalidation messages and relfilenodes,
saving considerable space for the vast majority of transaction commits.
XLOG_XACT_COMMIT keeps same definition as XLOG_PAGE_MAGIC 0xD067 and earlier.
Leonardo Francalanci and Simon Riggs
The previous coding was ugly, as it marked special tokens as such in the
wrong stage, relying on workarounds to figure out if they had been
quoted in the original or not. This made it impossible to have specific
keywords be recognized as such only in certain positions in HBA lines,
for example. Fix by restructuring the parser code so that it remembers
whether tokens were quoted or not. This eliminates widespread knowledge
of possible known keywords for all fields.
Also improve memory management in this area, to use memory contexts that
are reset as a whole instead of using retail pfrees; this removes a
whole lotta crufty (and probably slow) code.
Instead of calling strlen() three times in next_field_expand on the
returned token to find out whether there was a comma (and strip it),
pass back the info directly from the callee, which is simpler.
In passing, update historical artifacts in hba.c API.
Authors: Brendan Jurd, Alvaro Herrera
Reviewed by Pavel Stehule
Fill in the collation columns of the views attributes, columns,
domains, and element_types. Also update collation information in
sql_implementation_info.
WAL records of type XLOG_BTREE_REUSE_PAGE were generated using a
latestRemovedXid one higher than actually needed because xid used was
page opaque->btpo.xact rather than an actually removed xid.
Noticed on an otherwise quiet system by Noah Misch.
Noah Misch and Simon Riggs
Since the names try_relation_openrv() and try_heap_openrv() don't seem
quite appropriate, rename the functions to relation_openrv_extended()
and heap_openrv_extended(). This is also more general, if we have a
future need for additional parameters that are of interest to only a
few callers.
This is infrastructure for a forthcoming patch to allow
get_object_address() to take a missing_ok argument as well.
Patch by me, review by Noah Misch.
It's been like this since HOT was originally introduced, but the logic
is complex enough that this is a recipe for bugs, as we've already
found out with SSI. So refactor heap_hot_search_buffer() so that it
can satisfy the needs of index_getnext(), and make index_getnext() use
that rather than duplicating the logic.
This change was originally proposed by Heikki Linnakangas as part of a
larger refactoring oriented towards allowing index-only scans. I
extracted and adjusted this part, since it seems to have independent
merit. Review by Jeff Davis.
The --flag argument can be used to tell xgettext the arguments of
which functions should be flagged with c-format in the PO files,
instead of guessing based on the presence of format specifiers, which
fails if no format specifiers are present but the translation
accidentally introduces one.
Appropriate flag settings have been added for each message catalog.
based on a patch by Christoph Berg for bug #6066
Put gettext trigger words that are common to the backend and backend
modules into a makefile variable to include everywhere, to avoid
error-prone repetitions.
It currently doesn't make a difference, but it's inconsistent with
most other usage, and it might interfere with a future patch, so I'll
change it all in a separate commit.
Also, replace tabs with spaces for alignment.
s/const//g wasn't exactly what I was suggesting here ... parameter
declarations of the form "const structtype *param" are good and useful,
so put those occurrences back. Likewise, avoid casting away the const
in a "const void *" parameter.
backend/Makefile was treating errcodes.h as a header always generated
during build, but actually it's a header provided in tarballs. Hence,
must use the absolute-symlink recipe, not the relative-symlink one.
Per bug #6072 from Hartmut Raschick.
As Tom Lane pointed out, "const Relation foo" doesn't guarantee that you
can't modify the data the "foo" pointer points to. It just means that you
can't change the pointer to point to something else within the function,
which is not very useful.
This involves two main changes from the previous behavior. First,
when we set a bit in the visibility map, emit a new WAL record of type
XLOG_HEAP2_VISIBLE. Replay sets the page-level PD_ALL_VISIBLE bit and
the visibility map bit. Second, when inserting, updating, or deleting
a tuple, we can no longer get away with clearing the visibility map
bit after releasing the lock on the corresponding heap page, because
an intervening crash might leave the visibility map bit set and the
page-level bit clear. Making this work requires a bit of interface
refactoring.
In passing, a few minor but related cleanups: change the test in
visibilitymap_set and visibilitymap_clear to throw an error if the
wrong page (or no page) is pinned, rather than silently doing nothing;
this case should never occur. Also, remove duplicate definitions of
InvalidXLogRecPtr.
Patch by me, review by Noah Misch.
This is just like serial and bigserial, except it generates an int2
column rather than int4 or int8.
Mike Pultz, reviewed by Brar Piening and Josh Kupershmidt
This allows deadlock_timeout to be reduced for transactions that are
particularly likely to be involved in a deadlock, thus detecting it
more quickly. It is also potentially useful as a poor-man's deadlock
priority mechanism: a transaction with a high deadlock_timeout is less
likely to be chosen as the victim than one with a low
deadlock_timeout. Since that could be used to game the system, we
make this PGC_SUSET rather than PGC_USERSET.
At some point, it might be worth thinking about a more explicit
priority mechanism, since using this is far from fool-proof. But
let's see whether there's enough use case to justify the additional
work before we go down that route.
Noah Misch, reviewed by Shigeru Hanada
Initially, we use this only to eliminate calls to the varchar()
function in cases where the length is not being reduced and, therefore,
the function call is equivalent to a RelabelType operation. The most
significant effect of this is that we can avoid a table rewrite when
changing a varchar(X) column to a varchar(Y) column, where Y > X.
Noah Misch, reviewed by me and Alexey Klyukin
already been marked as PREPARED cannot be killed. Kill the current
transaction instead.
One of the prepared_xacts regression tests actually hits this bug. I
removed the anomaly from the duplicate-gids test so that it fails in the
intended way, and added a new test to check serialization failures with
a prepared transaction.
Dan Ports
MARKED_FOR_DEATH flags into one. We still need the ROLLED_BACK flag to
mark transactions that are in the process of being rolled back. To be
precise, ROLLED_BACK now means that a transaction has already been
discounted from the count of transactions with the oldest xmin, but not
yet removed from the list of active transactions.
Dan Ports
When recursing after an optimization in pull_up_sublinks_qual_recurse, the
available_rels value passed down must include only the relations that are
in the righthand side of the new SEMI or ANTI join; it's incorrect to pull
up a sub-select that refers to other relations, as seen in the added test
case. Per report from BangarRaju Vadapalli.
While at it, rethink the idea of recursing below a NOT EXISTS. That is
essentially the same situation as pulling up ANY/EXISTS sub-selects that
are in the ON clause of an outer join, and it has the same disadvantage:
we'd force the two joins to be evaluated according to the syntactic nesting
order, because the lower join will most likely not be able to commute with
the ANTI join. That could result in having to form a rather large join
product, whereas the handling of a correlated subselect is not quite that
dumb. So until we can handle those cases better, #ifdef NOT_USED that
case. (I think it's okay to pull up in the EXISTS/ANY cases, because SEMI
joins aren't so inflexible about ordering.)
Back-patch to 8.4, same as for previous patch in this area. Fortunately
that patch hadn't made it into any shipped releases yet.
Some callers were creating copies of tuple descriptors to pass to that
function, stating in code comments that it was necessary because it
modified the passed descriptor. Code inspection reveals this not to be
true, and indeed not all callers are passing copies in the first place.
So remove the extra ones and the misleading comments about this behavior
as well.
I mis-simplified the test where ANALYZE decided if it could get away
without doing anything: under the new regime, that's never allowed. Per
bug #6068 from Jeff Janes. Back-patch to 8.4, just like previous patch.
The previous code went into an infinite loop after overflow. In fact,
an overflow is not really an error; it just means that the current
value is the last one we need to return. So, just arrange to stop
immediately when overflow is detected.
Back-patch all the way.
The code that created the init fork neglected to make sure that the
relation was open at the smgr level before attempting to invoke smgr.
This didn't happen every time; only when the relcache entry was rebuilt
along the way.
Per report from Garick Hamlin.
There's no need to add space for startupBufferPinWaitBufId, because
it's part of the PROC_HDR object for which this function already
allocates space.
This has been wrong for a while, but the only consequence is that our
shared memory allocation is increased by 4 bytes, so no back-patch.
We had already converted most places to this style, but this patch gets the
last few that were still doing it the old way. The main advantage is that
this exposes a greppable name for each target column, rather than having
to rely on comments (which a couple of places failed to provide anyhow).
Richard Hopkins, additional work by me to clean up update_attstats() too
gcc 4.6 complains about these because of the new option
-Wunused-but-set-variable which comes in with -Wall, so cast them to
void, which avoids the warning.
SSI is based on, as well as the optimizations about relative commit times
and read-only transactions. Plus a bunch of other misc fixes and
improvements.
Dan Ports
Btree pages were recycled after VACUUM deletes all records on a
page and then a subsequent VACUUM occurs after the RecentXmin
horizon is reached. Using RecentXmin meant that we did not respond
correctly to the user controls provide to avoid Hot Standby
conflicts and so spurious conflicts could be generated in some
workload combinations. We now reuse pages only when we reach
RecentGlobalXmin, which can be much later in the presence of long
running queries and is also controlled by vacuum_defer_cleanup_age
and hot_standby_feedback.
Noah Misch and Simon Riggs
Per recommendation from Peter. Neither choice is bulletproof, but this
is the existing style and it does help prevent unexpected environment
variable substitution.
The initial commit of the ALTER TABLE ADD FOREIGN KEY NOT VALID feature
failed to support labeling such constraints as deferrable. The best fix
for this seems to be to fold NOT VALID into ConstraintAttributeSpec.
That's a bit more general than the documented syntax, but it allows
better-targeted syntax error messages.
In addition, do some mostly-but-not-entirely-cosmetic code review for
the whole NOT VALID patch.
This oversight could result in a tuplestore using much more than the
intended amount of memory. It would only happen in a code path that loaded
a tuplestore via tuplestore_putvalues(), and many of those won't emit huge
amounts of data; but cases such as holdable cursors and plpgsql's RETURN
NEXT command could have the problem. The fix ensures that the tuplestore
will switch to write-to-disk mode when it overruns work_mem.
The potential overrun was finite, because we would still count the space
used by the tuple pointer array, so the tuplestore code would eventually
flip into write-to-disk mode anyway. When storing wide tuples we would
go far past the expected work_mem usage before that happened; but this
may account for the lack of prior reports.
Back-patch to 8.4, where tuplestore_putvalues was introduced.
Per bug #6061 from Yann Delorme.
the marked-for-death flag. It was only set for a fleeting moment while a
transaction was being cleaned up at rollback. All the places that checked
for the rolled-back flag should also check the marked-for-death flag, as
both flags mean that the transaction will roll back. I also renamed the
marked-for-death into "doomed", which is a lot shorter name.
snapshots, like in REINDEX, are basically non-transactional operations. The
DDL operation itself might participate in SSI, but there's separate
functions for that.
Kevin Grittner and Dan Ports, with some changes by me.
The old code creates three separate arrays when only one is needed,
using two different shmem allocation functions for no obvious reason.
It also strangely splits up the initialization of AuxilaryProcs
between the top and bottom of the function to no evident purpose.
Review by Tom Lane.
ReadRecord's habit of using both direct references to tmpRecPtr and
references to *RecPtr (which is pointing at tmpRecPtr) triggers an
optimization bug in gcc 4.6.0, which apparently has forgotten about
aliasing rules. Avoid the compiler bug, and make the code more readable
to boot, by getting rid of the direct references. Improve the comments
while at it.
Back-patch to all supported versions, in case they get built with 4.6.0.
Tom Lane, with some cosmetic suggestions from Alex Hunsaker
Even if a flag is modified only by the backend owning the transaction, it's
not safe to modify it without a lock. Another backend might be setting or
clearing a different flag in the flags field concurrently, and that
operation might be lost because setting or clearing a bit in a word is not
atomic.
Make did-write flag a simple backend-private boolean variable, because it
was only set or tested in the owning backend (except when committing a
prepared transaction, but it's not worthwhile to optimize for the case of a
read-only prepared transaction). This also eliminates the need to add
locking where that flag is set.
Also, set the did-write flag when doing DDL operations like DROP TABLE or
TRUNCATE -- that was missed earlier.
"Blind writes" are a mechanism to push buffers down to disk when
evicting them; since they may belong to different databases than the one
a backend is connected to, the backend does not necessarily have a
relation to link them to, and thus no way to blow them away. We were
keeping those files open indefinitely, which would cause a problem if
the underlying table was deleted, because the operating system would not
be able to reclaim the disk space used by those files.
To fix, have bufmgr mark such files as transient to smgr; the lower
layer is allowed to close the file descriptor when the current
transaction ends. We must be careful to have any other access of the
file to remove the transient markings, to prevent unnecessary expensive
system calls when evicting buffers belonging to our own database (which
files we're likely to require again soon.)
This commit fixes a bug in the previous one, which neglected to cleanly
handle the LRU ring that fd.c uses to manage open files, and caused an
unacceptable failure just before beta2 and was thus reverted.
"Blind writes" are a mechanism to push buffers down to disk when
evicting them; since they may belong to different databases than the one
a backend is connected to, the backend does not necessarily have a
relation to link them to, and thus no way to blow them away. We were
keeping those files open indefinitely, which would cause a problem if
the underlying table was deleted, because the operating system would not
be able to reclaim the disk space used by those files.
To fix, have bufmgr mark such files as transient to smgr; the lower
layer is allowed to close the file descriptor when the current
transaction ends. We must be careful to have any other access of the
file to remove the transient markings, to prevent unnecessary expensive
system calls when evicting buffers belonging to our own database (which
files we're likely to require again soon.)
SimpleLruTruncate() a page number that's "in the future", because it will
issue a warning and refuse to truncate anything. Instead, we leave behind
the latest segment. If the slru is not needed before XID wrap-around, the
segment will appear as new again, and not be cleaned up until it gets old
enough again. That's a bit unpleasant, but better than not cleaning up
anything.
Also, fix broken calculation to check and warn if the span of the OldSerXid
SLRU is getting too large to fit in the 64k SLRU pages that we have
available. It was not XID wraparound aware.
Kevin Grittner and me.
This use-case was broken in commit 529cb267a6
of 2010-10-21, in which I commented "For the moment, we just forbid such
matching. We might later wish to insert an automatic downcast to the
underlying array type, but such a change should also change matching of
domains to ANYELEMENT for consistency". We still lack consensus about what
to do with ANYELEMENT; but not matching ANYARRAY is a clear loss of
functionality compared to prior releases, so let's go ahead and make that
happen. Per complaint from Regina Obe and extensive subsequent discussion.
Truncating or dropping a table is treated like deletion of all tuples, and
check for conflicts accordingly. If a table is clustered or rewritten by
ALTER TABLE, all predicate locks on the heap are promoted to relation-level
locks, because the tuple or page ids of any existing tuples will change and
won't be valid after rewriting the table. Arguably ALTER TABLE should be
treated like a mass-UPDATE of every row, but if you e.g change the datatype
of a column, you could also argue that it's just a change to the physical
layout, not a logical change. Reindexing promotes all locks on the index to
relation-level lock on the heap.
Kevin Grittner, with a lot of cosmetic changes by me.
This has never been supported, but we previously let md.c issue the
complaint for us at whatever point we tried to examine the backing file.
Now we print a nicer error message.
Per bug #6041, reported by Emanuel, and extensive discussion with Tom
Lane over where to put the check.
Since the original implementation of CTEs only allowed them in SELECT
queries, the rule rewriter did not expect to find any CTEs in statements
being rewritten by ON INSERT/UPDATE/DELETE rules. We had dealt with this
to some extent but the code was still several bricks shy of a load, as
illustrated in bug #6051 from Jehan-Guillaume de Rorthais.
In particular, we have to be able to copy CTEs from the original query's
cteList into that of a rule action, in case the rule action references the
CTE (which it pretty much always will). This also implies we were doing
things in the wrong order in RewriteQuery: we have to recursively rewrite
the CTE queries before expanding the main query, so that we have the
rewritten queries available to copy.
There are unpleasant limitations yet to resolve here, but at least we now
throw understandable FEATURE_NOT_SUPPORTED errors for them instead of just
failing with bizarre implementation-dependent errors. In particular, we
can't handle propagating the same CTE into multiple post-rewrite queries
(because then the CTE would be evaluated multiple times), and we can't cope
with conflicts between CTE names in the original query and in the rule
actions.
This avoids an Assert failure when we try to use ordinary index fetches
while checking for exclusion conflicts. Per report from Noah Misch.
No need for back-patch because the Assert wasn't there before 9.1.
We were trying to make that strictly an internal implementation detail,
but it turns out that it's exposed anyway when dumping a view defined
like
CREATE VIEW test_view AS VALUES (1), (2), (3) ORDER BY 1;
This comes out as
CREATE VIEW ... ORDER BY "*VALUES*".column1;
which fails to parse when reloading the dump.
Hacking ruleutils.c to suppress the column qualification looks like it'd
be a risky business, so instead promote the RTE alias to full-fledged
usability.
Per bug #6049 from Dylan Adams. Back-patch to all supported branches.
This case was missed when NOT VALID constraints were first introduced in
commit 722bf7017b by Simon Riggs on
2011-02-08. Among other things, it causes pg_dump to omit the NOT VALID
flag when dumping such constraints, which may cause them to fail to
load afterwards, if they contained values failing the constraint.
Per report from Thom Brown.
The existence of a btree opclass accepting composite types caused us to
assume that every composite type is sortable. This isn't true of course;
we need to check if the column types are all sortable. There was logic
for this for the case of array comparison (ie, check that the element
type is sortable), but we missed the point for rowtypes. Per Teodor's
report of an ANALYZE failure for an unsortable composite type.
Rather than just add some more ad-hoc logic for this, I moved knowledge of
the issue into typcache.c. The typcache will now only report out array_eq,
record_cmp, and friends as usable operators if the array or composite type
will work with those functions.
Unfortunately we don't have enough info to do this for anonymous RECORD
types; in that case, just assume it will work, and take the runtime failure
as before if it doesn't.
This patch might be a candidate for back-patching at some point, but
given the lack of complaints from the field, I'd rather just test it in
HEAD for now.
Note: most of the places touched in this patch will need further work
when we get around to supporting hashing of record types.
We need this now because we allow domains over arrays, and we'll probably
allow domains over composites pretty soon, which makes the problem even
more obvious.
Although domains over arrays also exist in previous versions, this does not
need to be back-patched, because the coding used in older versions
successfully "looked through" domains over arrays. The problem is exposed
by not treating a domain as having a typelem.
Problem identified by Noah Misch, though I did not use his patch, since
it would require additional work to handle domains over composites that
way. This approach is more future-proof.
My previous commit disallowed this operation, but did nothing about
cleaning up the damage if one had already been done. With the operation
disallowed, it's okay to just forcibly clear xmax in a sequence's tuple,
since any value seen there could not represent a live transaction's lock.
So, any sequence-specific operation will repair the problem automatically,
whether or not the user has already seen "could not access status of
transaction" failures.
We can't allow this because such an operation stores its transaction XID
into the sequence tuple's xmax. Because VACUUM doesn't process sequences
(and we don't want it to start doing so), such an xmax value won't get
frozen, meaning it will eventually refer to nonexistent pg_clog storage,
and even wrap around completely. Since the row lock is ignored by nextval
and setval, the usefulness of the operation is highly debatable anyway.
Per reports of trouble with pgpool 3.0, which had ill-advisedly started
using such commands as a form of locking.
In HEAD, also disallow SELECT FOR UPDATE/SHARE on toast tables. Although
this does work safely given the current implementation, there seems no
good reason to allow it. I refrained from changing that behavior in
back branches, however.
This unifies a bunch of ugly #ifdef's in one place. Per discussion,
we only need this where HAVE_UNIX_SOCKETS, so no need to cover Windows.
Marko Kreen, some adjustment by Tom Lane
Per experimentation with a recent example, in which unreasonable amounts
of time could elapse before the backend would respond to a query-cancel.
This might be something to back-patch, but the patch doesn't apply cleanly
because this code was rewritten for 9.1. Given the lack of field
complaints I won't bother for now.
Cédric Villemain
Apparently sane-looking penalty code might return small negative values,
for example because of roundoff error. This will confuse places like
gistchoose(). Prevent problems by clamping negative penalty values to
zero. (Just to be really sure, I also made it force NaNs to zero.)
Back-patch to all supported branches.
Alexander Korotkov
For consistency, have all non-ASCII characters from contributors'
names in the source be in UTF-8. But remove some other more
gratuitous uses of non-ASCII characters.
It turns out the reason we hadn't found out about the portability issues
with our credential-control-message code is that almost no modern platforms
use that code at all; the ones that used to need it now offer getpeereid(),
which we choose first. The last holdout was NetBSD, and they added
getpeereid() as of 5.0. So far as I can tell, the only live platform on
which that code was being exercised was Debian/kFreeBSD, ie, FreeBSD kernel
with Linux userland --- since glibc doesn't provide getpeereid(), we fell
back to the control message code. However, the FreeBSD kernel provides a
LOCAL_PEERCRED socket parameter that's functionally equivalent to Linux's
SO_PEERCRED. That is both much simpler to use than control messages, and
superior because it doesn't require receiving a message from the other end
at just the right time.
Therefore, add code to use LOCAL_PEERCRED when necessary, and rip out all
the credential-control-message code in the backend. (libpq still has such
code so that it can still talk to pre-9.1 servers ... but eventually we can
get rid of it there too.) Clean up related autoconf probes, too.
This means that libpq's requirepeer parameter now works on exactly the same
platforms where the backend supports peer authentication, so adjust the
documentation accordingly.
Even though our existing code for handling credentials control messages has
been basically unchanged since 2001, it was fundamentally wrong: it did not
ensure proper alignment of the supplied buffer, and it was calculating
buffer sizes and message sizes incorrectly. This led to failures on
platforms where alignment padding is relevant, for instance FreeBSD on
64-bit platforms, as seen in a recent Debian bug report passed on by
Martin Pitt (http://bugs.debian.org//cgi-bin/bugreport.cgi?bug=612888).
Rewrite to do the message-whacking using the macros specified in RFC 2292,
following a suggestion from Theo de Raadt in that thread. Tested by me
on Debian/kFreeBSD-amd64; since OpenBSD and NetBSD document the identical
CMSG API, it should work there too.
Back-patch to all supported branches.
When we added the ability for vacuum to skip heap pages by consulting the
visibility map, we made it just not update the reltuples/relpages
statistics if it skipped any pages. But this could leave us with extremely
out-of-date stats for a table that contains any unchanging areas,
especially for TOAST tables which never get processed by ANALYZE. In
particular this could result in autovacuum making poor decisions about when
to process the table, as in recent report from Florian Helmberger. And in
general it's a bad idea to not update the stats at all. Instead, use the
previous values of reltuples/relpages as an estimate of the tuple density
in unvisited pages. This approach results in a "moving average" estimate
of reltuples, which should converge to the correct value over multiple
VACUUM and ANALYZE cycles even when individual measurements aren't very
good.
This new method for updating reltuples is used by both VACUUM and ANALYZE,
with the result that we no longer need the grotty interconnections that
caused ANALYZE to not update the stats depending on what had happened
in the parent VACUUM command.
Also, fix the logic for skipping all-visible pages during VACUUM so that it
looks ahead rather than behind to decide what to do, as per a suggestion
from Greg Stark. This eliminates useless scanning of all-visible pages at
the start of the relation or just after a not-all-visible page. In
particular, the first few pages of the relation will not be invariably
included in the scanned pages, which seems to help in not overweighting
them in the reltuples estimate.
Back-patch to 8.4, where the visibility map was introduced.
Since we now include a sample line for replication on local
connections in pg_hba.conf, don't include it where local
connections aren't available (such as on win32).
Also make sure we use authmethodlocal and not authmethod on
the sample line.
Magnus Hagander
Tom Lane
Alvaro Herrera
Heikki Linnakangas
Peter Eisentraut
Simon Riggs
Robert Haas
Michael Meskes
Bruce Momjian