Commit Graph

420 Commits

Author SHA1 Message Date
Tom Lane 434873806a Fix some oversights in BRIN patch.
Remove HeapScanDescData.rs_initblock, which wasn't being used for anything
in the final version of the patch.

Fix IndexBuildHeapScan so that it supports syncscan again; the patch
broke synchronous scanning for index builds by forcing rs_startblk
to zero even when the caller did not care about that and had asked
for syncscan.

Add some commentary and usage defenses to heap_setscanlimits().

Fix heapam so that asking for rs_numblocks == 0 does what you would
reasonably expect.  As coded it amounted to requesting a whole-table
scan, because those "--x <= 0" tests on an unsigned variable would
behave surprisingly.
2015-07-21 13:38:24 -04:00
Simon Riggs 66fbcb0d2e Avoid hot standby cancels from VAC FREEZE
VACUUM FREEZE generated false cancelations of standby queries on an
otherwise idle master. Caused by an off-by-one error on cutoff_xid
which goes back to original commit.

Backpatch to all versions 9.0+

Analysis and report by Marco Nenciarini

Bug fix by Simon Riggs
2015-06-27 00:41:47 +01:00
Heikki Linnakangas 4b8e24b9ad Fix a couple of bugs with wal_log_hints.
1. Replay of the WAL record for setting a bit in the visibility map
contained an assertion that a full-page image of that record type can only
occur with checksums enabled. But it can also happen with wal_log_hints, so
remove the assertion. Unlike checksums, wal_log_hints can be changed on the
fly, so it would be complicated to figure out if it was enabled at the time
that the WAL record was generated.

2. wal_log_hints has the same effect on the locking needed to read the LSN
of a page as data checksums. BufferGetLSNAtomic() didn't get the memo.

Backpatch to 9.4, where wal_log_hints was added.
2015-06-26 12:38:24 +03:00
Bruce Momjian 807b9e0dff pgindent run for 9.5 2015-05-23 21:35:49 -04:00
Heikki Linnakangas 4fc72cc7bb Collection of typo fixes.
Use "a" and "an" correctly, mostly in comments. Two error messages were
also fixed (they were just elogs, so no translation work required). Two
function comments in pg_proc.h were also fixed. Etsuro Fujita reported one
of these, but I found a lot more with grep.

Also fix a few other typos spotted while grepping for the a/an typos.
For example, "consists out of ..." -> "consists of ...". Plus a "though"/
"through" mixup reported by Euler Taveira.

Many of these typos were in old code, which would be nice to backpatch to
make future backpatching easier. But much of the code was new, and I didn't
feel like crafting separate patches for each branch. So no backpatching.
2015-05-20 16:56:22 +03:00
Magnus Hagander 3b075e9d7b Fix typos in comments
Dmitriy Olshevskiy
2015-05-17 14:58:04 +02:00
Simon Riggs f6d208d6e5 TABLESAMPLE, SQL Standard and extensible
Add a TABLESAMPLE clause to SELECT statements that allows
user to specify random BERNOULLI sampling or block level
SYSTEM sampling. Implementation allows for extensible
sampling functions to be written, using a standard API.
Basic version follows SQLStandard exactly. Usable
concrete use cases for the sampling API follow in later
commits.

Petr Jelinek

Reviewed by Michael Paquier and Simon Riggs
2015-05-15 14:37:10 -04:00
Andres Freund e8898e9169 Minor ON CONFLICT related comments and doc fixes.
Geoff Winkless, Stephen Frost, Peter Geoghegan and me.
2015-05-08 19:24:14 +02:00
Andres Freund 168d5805e4 Add support for INSERT ... ON CONFLICT DO NOTHING/UPDATE.
The newly added ON CONFLICT clause allows to specify an alternative to
raising a unique or exclusion constraint violation error when inserting.
ON CONFLICT refers to constraints that can either be specified using a
inference clause (by specifying the columns of a unique constraint) or
by naming a unique or exclusion constraint.  DO NOTHING avoids the
constraint violation, without touching the pre-existing row.  DO UPDATE
SET ... [WHERE ...] updates the pre-existing tuple, and has access to
both the tuple proposed for insertion and the existing tuple; the
optional WHERE clause can be used to prevent an update from being
executed.  The UPDATE SET and WHERE clauses have access to the tuple
proposed for insertion using the "magic" EXCLUDED alias, and to the
pre-existing tuple using the table name or its alias.

This feature is often referred to as upsert.

This is implemented using a new infrastructure called "speculative
insertion". It is an optimistic variant of regular insertion that first
does a pre-check for existing tuples and then attempts an insert.  If a
violating tuple was inserted concurrently, the speculatively inserted
tuple is deleted and a new attempt is made.  If the pre-check finds a
matching tuple the alternative DO NOTHING or DO UPDATE action is taken.
If the insertion succeeds without detecting a conflict, the tuple is
deemed inserted.

To handle the possible ambiguity between the excluded alias and a table
named excluded, and for convenience with long relation names, INSERT
INTO now can alias its target table.

Bumps catversion as stored rules change.

Author: Peter Geoghegan, with significant contributions from Heikki
    Linnakangas and Andres Freund. Testing infrastructure by Jeff Janes.
Reviewed-By: Heikki Linnakangas, Andres Freund, Robert Haas, Simon Riggs,
    Dean Rasheed, Stephen Frost and many others.
2015-05-08 05:43:10 +02:00
Robert Haas 924bcf4f16 Create an infrastructure for parallel computation in PostgreSQL.
This does four basic things.  First, it provides convenience routines
to coordinate the startup and shutdown of parallel workers.  Second,
it synchronizes various pieces of state (e.g. GUCs, combo CID
mappings, transaction snapshot) from the parallel group leader to the
worker processes.  Third, it prohibits various operations that would
result in unsafe changes to that state while parallelism is active.
Finally, it propagates events that would result in an ErrorResponse,
NoticeResponse, or NotifyResponse message being sent to the client
from the parallel workers back to the master, from which they can then
be sent on to the client.

Robert Haas, Amit Kapila, Noah Misch, Rushabh Lathia, Jeevan Chalke.
Suggestions and review from Andres Freund, Heikki Linnakangas, Noah
Misch, Simon Riggs, Euler Taveira, and Jim Nasby.
2015-04-30 15:02:14 -04:00
Andres Freund 5aa2350426 Introduce replication progress tracking infrastructure.
When implementing a replication solution ontop of logical decoding, two
related problems exist:
* How to safely keep track of replication progress
* How to change replication behavior, based on the origin of a row;
  e.g. to avoid loops in bi-directional replication setups

The solution to these problems, as implemented here, consist out of
three parts:

1) 'replication origins', which identify nodes in a replication setup.
2) 'replication progress tracking', which remembers, for each
   replication origin, how far replay has progressed in a efficient and
   crash safe manner.
3) The ability to filter out changes performed on the behest of a
   replication origin during logical decoding; this allows complex
   replication topologies. E.g. by filtering all replayed changes out.

Most of this could also be implemented in "userspace", e.g. by inserting
additional rows contain origin information, but that ends up being much
less efficient and more complicated.  We don't want to require various
replication solutions to reimplement logic for this independently. The
infrastructure is intended to be generic enough to be reusable.

This infrastructure also replaces the 'nodeid' infrastructure of commit
timestamps. It is intended to provide all the former capabilities,
except that there's only 2^16 different origins; but now they integrate
with logical decoding. Additionally more functionality is accessible via
SQL.  Since the commit timestamp infrastructure has also been introduced
in 9.5 (commit 73c986add) changing the API is not a problem.

For now the number of origins for which the replication progress can be
tracked simultaneously is determined by the max_replication_slots
GUC. That GUC is not a perfect match to configure this, but there
doesn't seem to be sufficient reason to introduce a separate new one.

Bumps both catversion and wal page magic.

Author: Andres Freund, with contributions from Petr Jelinek and Craig Ringer
Reviewed-By: Heikki Linnakangas, Petr Jelinek, Robert Haas, Steve Singer
Discussion: 20150216002155.GI15326@awork2.anarazel.de,
    20140923182422.GA15776@alap3.anarazel.de,
    20131114172632.GE7522@alap2.anarazel.de
2015-04-29 19:30:53 +02:00
Alvaro Herrera 27846f02c1 Optimize locking a tuple already locked by another subxact
Locking and updating the same tuple repeatedly led to some strange
multixacts being created which had several subtransactions of the same
parent transaction holding locks of the same strength.  However,
once a subxact of the current transaction holds a lock of a given
strength, it's not necessary to acquire the same lock again.  This made
some coding patterns much slower than required.

The fix is twofold.  First we change HeapTupleSatisfiesUpdate to return
HeapTupleBeingUpdated for the case where the current transaction is
already a single-xid locker for the given tuple; it used to return
HeapTupleMayBeUpdated for that case.  The new logic is simpler, and the
change to pgrowlocks is a testament to that: previously we needed to
check for the single-xid locker separately in a very ugly way.  That
test is simpler now.

As fallout from the HTSU change, some of its callers need to be amended
so that tuple-locked-by-own-transaction is taken into account in the
BeingUpdated case rather than the MayBeUpdated case.  For many of them
there is no difference; but heap_delete() and heap_update now check
explicitely and do not grab tuple lock in that case.

The HTSU change also means that routine MultiXactHasRunningRemoteMembers
introduced in commit 11ac4c73cb is no longer necessary and can be
removed; the case that used to require it is now handled naturally as
result of the changes to heap_delete and heap_update.

The second part of the fix to the performance issue is to adjust
heap_lock_tuple to avoid the slowness:

1. Previously we checked for the case that our own transaction already
held a strong enough lock and returned MayBeUpdated, but only in the
multixact case.  Now we do it for the plain Xid case as well, which
saves having to LockTuple.

2. If the current transaction is the only locker of the tuple (but with
a lock not as strong as what we need; otherwise it would have been
caught in the check mentioned above), we can skip sleeping on the
multixact, and instead go straight to create an updated multixact with
the additional lock strength.

3. Most importantly, make sure that both the single-xid-locker case and
the multixact-locker case optimization are applied always.  We do this
by checking both in a single place, rather than them appearing in two
separate portions of the routine -- something that is made possible by
the HeapTupleSatisfiesUpdate API change.  Previously we would only check
for the single-xid case when HTSU returned MayBeUpdated, and only
checked for the multixact case when HTSU returned BeingUpdated.  This
was at odds with what HTSU actually returned in one case: if our own
transaction was locker in a multixact, it returned MayBeUpdated, so the
optimization never applied.  This is what led to the large multixacts in
the first place.

Per bug report #8470 by Oskari Saarenmaa.
2015-04-10 13:47:15 -03:00
Tom Lane e1a11d9311 Use FLEXIBLE_ARRAY_MEMBER for HeapTupleHeaderData.t_bits[].
This requires changing quite a few places that were depending on
sizeof(HeapTupleHeaderData), but it seems for the best.

Michael Paquier, some adjustments by me
2015-02-21 15:13:06 -05:00
Heikki Linnakangas 57fe246890 Fix reference-after-free when waiting for another xact due to constraint.
If an insertion or update had to wait for another transaction to finish,
because there was another insertion with conflicting key in progress,
we would pass a just-free'd item pointer to XactLockTableWait().

All calls to XactLockTableWait() and MultiXactIdWait() had similar issues.
Some passed a pointer to a buffer in the buffer cache, after already
releasing the lock. The call in EvalPlanQualFetch had already released the
pin too. All but the call in execUtils.c would merely lead to reporting a
bogus ctid, however (or an assertion failure, if enabled).

All the callers that passed HeapTuple->t_data->t_ctid were slightly bogus
anyway: if the tuple was updated (again) in the same transaction, its ctid
field would point to the next tuple in the chain, not the tuple itself.

Backpatch to 9.4, where the 'ctid' argument to XactLockTableWait was added
(in commit f88d4cfc)
2015-02-04 16:00:34 +02:00
Bruce Momjian 4baaf863ec Update copyright for 2015
Backpatch certain files through 9.0
2015-01-06 11:43:47 -05:00
Alvaro Herrera d5e3d1e969 Fix thinko in lock mode enum
Commit 0e5680f473 contained a thinko
mixing LOCKMODE with LockTupleMode.  This caused misbehavior in the case
where a tuple is marked with a multixact with at most a FOR SHARE lock,
and another transaction tries to acquire a FOR NO KEY EXCLUSIVE lock;
this case should block but doesn't.

Include a new isolation tester spec file to explicitely try all the
tuple lock combinations; without the fix it shows the problem:

    starting permutation: s1_begin s1_lcksvpt s1_tuplock2 s2_tuplock3 s1_commit
    step s1_begin: BEGIN;
    step s1_lcksvpt: SELECT * FROM multixact_conflict FOR KEY SHARE; SAVEPOINT foo;
    a

    1
    step s1_tuplock2: SELECT * FROM multixact_conflict FOR SHARE;
    a

    1
    step s2_tuplock3: SELECT * FROM multixact_conflict FOR NO KEY UPDATE;
    a

    1
    step s1_commit: COMMIT;

With the fixed code, step s2_tuplock3 blocks until session 1 commits,
which is the correct behavior.

All other cases behave correctly.

Backpatch to 9.3, like the commit that introduced the problem.
2015-01-04 15:48:29 -03:00
Alvaro Herrera 0e5680f473 Grab heavyweight tuple lock only before sleeping
We were trying to acquire the lock even when we were subsequently
not sleeping in some other transaction, which opens us up unnecessarily
to deadlocks.  In particular, this is troublesome if an update tries to
lock an updated version of a tuple and finds itself doing EvalPlanQual
update chain walking; more than two sessions doing this concurrently
will find themselves sleeping on each other because the HW tuple lock
acquisition in heap_lock_tuple called from EvalPlanQualFetch races with
the same tuple lock being acquired in heap_update -- one of these
sessions sleeps on the other one to finish while holding the tuple lock,
and the other one sleeps on the tuple lock.

Per trouble report from Andrew Sackville-West in
http://www.postgresql.org/message-id/20140731233051.GN17765@andrew-ThinkPad-X230

His scenario can be simplified down to a relatively simple
isolationtester spec file which I don't include in this commit; the
reason is that the current isolationtester is not able to deal with more
than one blocked session concurrently and it blocks instead of raising
the expected deadlock.  In the future, if we improve isolationtester, it
would be good to include the spec file in the isolation schedule.  I
posted it in
http://www.postgresql.org/message-id/20141212205254.GC1768@alvh.no-ip.org

Hat tip to Mark Kirkwood, who helped diagnose the trouble.
2014-12-26 13:52:27 -03:00
Tom Lane adbfab119b Remove dead code supporting mark/restore in SeqScan, TidScan, ValuesScan.
There seems no prospect that any of this will ever be useful, and indeed
it's questionable whether some of it would work if it ever got called;
it's certainly not been exercised in a very long time, if ever. So let's
get rid of it, and make the comments about mark/restore in execAmi.c less
wishy-washy.

The mark/restore support for Result nodes is also currently dead code,
but that's due to planner limitations not because it's impossible that
it could be useful.  So I left it in.
2014-11-20 20:20:54 -05:00
Heikki Linnakangas 2c03216d83 Revamp the WAL record format.
Each WAL record now carries information about the modified relation and
block(s) in a standardized format. That makes it easier to write tools that
need that information, like pg_rewind, prefetching the blocks to speed up
recovery, etc.

There's a whole new API for building WAL records, replacing the XLogRecData
chains used previously. The new API consists of XLogRegister* functions,
which are called for each buffer and chunk of data that is added to the
record. The new API also gives more control over when a full-page image is
written, by passing flags to the XLogRegisterBuffer function.

This also simplifies the XLogReadBufferForRedo() calls. The function can dig
the relation and block number from the WAL record, so they no longer need to
be passed as arguments.

For the convenience of redo routines, XLogReader now disects each WAL record
after reading it, copying the main data part and the per-block data into
MAXALIGNed buffers. The data chunks are not aligned within the WAL record,
but the redo routines can assume that the pointers returned by XLogRecGet*
functions are. Redo routines are now passed the XLogReaderState, which
contains the record in the already-disected format, instead of the plain
XLogRecord.

The new record format also makes the fixed size XLogRecord header smaller,
by removing the xl_len field. The length of the "main data" portion is now
stored at the end of the WAL record, and there's a separate header after
XLogRecord for it. The alignment padding at the end of XLogRecord is also
removed. This compansates for the fact that the new format would otherwise
be more bulky than the old format.

Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera,
Fujii Masao.
2014-11-20 18:46:41 +02:00
Heikki Linnakangas 81c4508196 Fix race condition between hot standby and restoring a full-page image.
There was a window in RestoreBackupBlock where a page would be zeroed out,
but not yet locked. If a backend pinned and locked the page in that window,
it saw the zeroed page instead of the old page or new page contents, which
could lead to missing rows in a result set, or errors.

To fix, replace RBM_ZERO with RBM_ZERO_AND_LOCK, which atomically pins,
zeroes, and locks the page, if it's not in the buffer cache already.

In stable branches, the old RBM_ZERO constant is renamed to RBM_DO_NOT_USE,
to avoid breaking any 3rd party extensions that might use RBM_ZERO. More
importantly, this avoids renumbering the other enum values, which would
cause even bigger confusion in extensions that use ReadBufferExtended, but
haven't been recompiled.

Backpatch to all supported versions; this has been racy since hot standby
was introduced.
2014-11-13 20:02:37 +02:00
Alvaro Herrera 7516f52594 BRIN: Block Range Indexes
BRIN is a new index access method intended to accelerate scans of very
large tables, without the maintenance overhead of btrees or other
traditional indexes.  They work by maintaining "summary" data about
block ranges.  Bitmap index scans work by reading each summary tuple and
comparing them with the query quals; all pages in the range are returned
in a lossy TID bitmap if the quals are consistent with the values in the
summary tuple, otherwise not.  Normal index scans are not supported
because these indexes do not store TIDs.

As new tuples are added into the index, the summary information is
updated (if the block range in which the tuple is added is already
summarized) or not; in the latter case, a subsequent pass of VACUUM or
the brin_summarize_new_values() function will create the summary
information.

For data types with natural 1-D sort orders, the summary info consists
of the maximum and the minimum values of each indexed column within each
page range.  This type of operator class we call "Minmax", and we
supply a bunch of them for most data types with B-tree opclasses.
Since the BRIN code is generalized, other approaches are possible for
things such as arrays, geometric types, ranges, etc; even for things
such as enum types we could do something different than minmax with
better results.  In this commit I only include minmax.

Catalog version bumped due to new builtin catalog entries.

There's more that could be done here, but this is a good step forwards.

Loosely based on ideas from Simon Riggs; code mostly by Álvaro Herrera,
with contribution by Heikki Linnakangas.

Patch reviewed by: Amit Kapila, Heikki Linnakangas, Robert Haas.
Testing help from Jeff Janes, Erik Rijkers, Emanuel Calvo.

PS:
  The research leading to these results has received funding from the
  European Union's Seventh Framework Programme (FP7/2007-2013) under
  grant agreement n° 318633.
2014-11-07 16:38:14 -03:00
Heikki Linnakangas 2076db2aea Move the backup-block logic from XLogInsert to a new file, xloginsert.c.
xlog.c is huge, this makes it a little bit smaller, which is nice. Functions
related to putting together the WAL record are in xloginsert.c, and the
lower level stuff for managing WAL buffers and such are in xlog.c.

Also move the definition of XLogRecord to a separate header file. This
causes churn in the #includes of all the files that write WAL records, and
redo routines, but it avoids pulling in xlog.h into most places.

Reviewed by Michael Paquier, Alvaro Herrera, Andres Freund and Amit Kapila.
2014-11-06 13:55:36 +02:00
Alvaro Herrera df630b0dd5 Implement SKIP LOCKED for row-level locks
This clause changes the behavior of SELECT locking clauses in the
presence of locked rows: instead of causing a process to block waiting
for the locks held by other processes (or raise an error, with NOWAIT),
SKIP LOCKED makes the new reader skip over such rows.  While this is not
appropriate behavior for general purposes, there are some cases in which
it is useful, such as queue-like tables.

Catalog version bumped because this patch changes the representation of
stored rules.

Reviewed by Craig Ringer (based on a previous attempt at an
implementation by Simon Riggs, who also provided input on the syntax
used in the current patch), David Rowley, and Álvaro Herrera.

Author: Thomas Munro
2014-10-07 17:23:34 -03:00
Heikki Linnakangas f8f4227976 Refactor per-page logic common to all redo routines to a new function.
Every redo routine uses the same idiom to determine what to do to a page:
check if there's a backup block for it, and if not read, the buffer if the
block exists, and check its LSN. Refactor that into a common function,
XLogReadBufferForRedo, making all the redo routines shorter and more
readable.

This has no user-visible effect, and makes no changes to the WAL format.

Reviewed by Andres Freund, Alvaro Herrera, Michael Paquier.
2014-09-02 15:10:28 +03:00
Alvaro Herrera 3adba73662 Revert XactLockTableWait context setup in conditional multixact wait
There's no point in setting up a context error callback when doing
conditional lock acquisition, because we never actually wait and so the
user wouldn't be able to see the context message anywhere.  In fact,
this is more in line with what ConditionalXactLockTableWait is doing.

Backpatch to 9.4, where this was added.
2014-08-25 15:33:17 -04:00
Alvaro Herrera 6f822952ee Use newly added InvalidCommandId instead of 0
The symbol was added by 71901ab6d; the original code was introduced by
6868ed749.  Development of both overlapped which is why we apparently
failed to notice.

This is a (very slight) behavior change, so I'm not backpatching this to
9.4 for now, even though the symbol does exist there.
2014-08-25 15:32:30 -04:00
Alvaro Herrera 01d15a2677 Fix outdated comment 2014-08-22 14:03:11 -04:00
Heikki Linnakangas 54685338e3 Move log_newpage and log_newpage_buffer to xlog.c.
log_newpage is used by many indexams, in addition to heap, but for
historical reasons it's always been part of the heapam rmgr. Starting with
9.3, we have another WAL record type for logging an image of a page,
XLOG_FPI. Simplify things by moving log_newpage and log_newpage_buffer to
xlog.c, and switch to using the XLOG_FPI record type.

Bump the WAL version number because the code to replay the old HEAP_NEWPAGE
records is removed.
2014-07-31 16:48:55 +03:00
Alvaro Herrera 0531549801 Avoid uselessly looking up old LOCK_ONLY multixacts
Commit 0ac5ad5134 removed an optimization in multixact.c that skipped
fetching members of MultiXactId that were older than our
OldestVisibleMXactId value.  The reason this was removed is that it is
possible for multixacts that contain updates to be older than that
value.  However, if the caller is certain that the multi does not
contain an update (because the infomask bits say so), it can pass this
info down to GetMultiXactIdMembers, enabling it to use the old
optimization.

Pointed out by Andres Freund in 20131121200517.GM7240@alap2.anarazel.de
2014-07-29 15:41:06 -04:00
Alvaro Herrera c2581794f3 Simplify multixact freezing a bit
Testing for abortedness of a multixact member that's being frozen is
unnecessary: we only need to know whether the transaction is still in
progress or committed to determine whether it must be kept or not.  This
let us simplify the code a bit and avoid a useless TransactionIdDidAbort
test.

Suggested by Andres Freund awhile back.
2014-07-29 15:40:55 -04:00
Andres Freund 626bfad6cc Fix decoding of consecutive MULTI_INSERTs emitted by one heap_multi_insert().
Commit 1b86c81d2d fixed the decoding of toasted columns for the rows
contained in one xl_heap_multi_insert record. But that's not actually
enough, because heap_multi_insert() will actually first toast all
passed in rows and then emit several *_multi_insert records; one for
each page it fills with tuples.

Add a XLOG_HEAP_LAST_MULTI_INSERT flag which is set in
xl_heap_multi_insert->flag denoting that this multi_insert record is
the last emitted by one heap_multi_insert() call. Then use that flag
in decode.c to only set clear_toast_afterwards in the right situation.

Expand the number of rows inserted via COPY in the corresponding
regression test to make sure that more than one heap page is filled
with tuples by one heap_multi_insert() call.

Backpatch to 9.4 like the previous commit.
2014-07-12 14:28:19 +02:00
Alvaro Herrera b277057648 Fix broken Assert() introduced by 8e9a16ab8f
Don't assert MultiXactIdIsRunning if the multi came from a tuple that
had been share-locked and later copied over to the new cluster by
pg_upgrade.  Doing that causes an error to be raised unnecessarily:
MultiXactIdIsRunning is not open to the possibility that its argument
came from a pg_upgraded tuple, and all its other callers are already
checking; but such multis cannot, obviously, have transactions still
running, so the assert is pointless.

Noticed while investigating the bogus pg_multixact/offsets/0000 file
left over by pg_upgrade, as reported by Andres Freund in
http://www.postgresql.org/message-id/20140530121631.GE25431@alap3.anarazel.de

Backpatch to 9.3, as the commit that introduced the buglet.
2014-06-27 14:43:39 -04:00
Robert Haas c922353b1c Check for interrupts during tuple-insertion loops.
Normally, this won't matter too much; but if I/O is really slow, for
example because the system is overloaded, we might write many pages
before checking for interrupts.  A single toast insertion might
write up to 1GB of data, and a multi-insert could write hundreds
of tuples (and their corresponding TOAST data).
2014-06-23 21:45:21 -04:00
Tom Lane b23b0f5588 Code review for recent changes in relcache.c.
rd_replidindex should be managed the same as rd_oidindex, and rd_keyattr
and rd_idattr should be managed like rd_indexattr.  Omissions in this area
meant that the bitmapsets computed for rd_keyattr and rd_idattr would be
leaked during any relcache flush, resulting in a slow but permanent leak in
CacheMemoryContext.  There was also a tiny probability of relcache entry
corruption if we ran out of memory at just the wrong point in
RelationGetIndexAttrBitmap.  Otherwise, the fields were not zeroed where
expected, which would not bother the code any AFAICS but could greatly
confuse anyone examining the relcache entry while debugging.

Also, create an API function RelationGetReplicaIndex rather than letting
non-relcache code be intimate with the mechanisms underlying caching of
that value (we won't even mention the memory leak there).

Also, fix a relcache flush hazard identified by Andres Freund:
RelationGetIndexAttrBitmap must not assume that rd_replidindex stays valid
across index_open.

The aspects of this involving rd_keyattr date back to 9.3, so back-patch
those changes.
2014-05-14 14:56:08 -04:00
Bruce Momjian 0a78320057 pgindent run for 9.4
This includes removing tabs after periods in C comments, which was
applied to back branches, so this change should not effect backpatching.
2014-05-06 12:12:18 -04:00
Heikki Linnakangas 1460b199e6 Assert that pre/post-fix updated tuples are on the same page during replay.
If they were not 'oldtup.t_data' would be dereferenced while set to NULL
in case of a full page image for block 0.

Do so primarily to silence coverity; but also to make sure this prerequisite
isn't changed without adapting the replay routine as that would appear to
work in many cases.

Andres Freund
2014-05-05 16:15:25 +03:00
Alvaro Herrera 1a917ae861 Fix race when updating a tuple concurrently locked by another process
If a tuple is locked, and this lock is later upgraded either to an
update or to a stronger lock, and in the meantime some other process
tries to lock, update or delete the same tuple, it (the tuple) could end
up being updated twice, or having conflicting locks held.

The reason for this is that the second updater checks for a change in
Xmax value, or in the HEAP_XMAX_IS_MULTI infomask bit, after noticing
the first lock; and if there's a change, it restarts and re-evaluates
its ability to update the tuple.  But it neglected to check for changes
in lock strength or in lock-vs-update status when those two properties
stayed the same.  This would lead it to take the wrong decision and
continue with its own update, when in reality it shouldn't do so but
instead restart from the top.

This could lead to either an assertion failure much later (when a
multixact containing multiple updates is detected), or duplicate copies
of tuples.

To fix, make sure to compare the other relevant infomask bits alongside
the Xmax value and HEAP_XMAX_IS_MULTI bit, and restart from the top if
necessary.

Also, in the belt-and-suspenders spirit, add a check to
MultiXactCreateFromMembers that a multixact being created does not have
two or more members that are claimed to be updates.  This should protect
against other bugs that might cause similar bogus situations.

Backpatch to 9.3, where the possibility of multixacts containing updates
was introduced.  (In prior versions it was possible to have the tuple
lock upgraded from shared to exclusive, and an update would not restart
from the top; yet we're protected against a bug there because there's
always a sleep to wait for the locking transaction to complete before
continuing to do anything.  Really, the fact that tuple locks always
conflicted with concurrent updates is what protected against bugs here.)

Per report from Andrew Dunstan and Josh Berkus in thread at
http://www.postgresql.org/message-id/534C8B33.9050807@pgexperts.com

Bug analysis by Andres Freund.
2014-04-24 15:41:55 -03:00
Heikki Linnakangas a4ad9afec2 Update obsolete comments.
We no longer have a TLI field in the page header.
2014-04-23 14:41:51 +03:00
Heikki Linnakangas b1236f4b7b Move multixid allocation out of critical section.
It can fail if you run out of memory.

This call was added in 9.3, so backpatch to 9.3 only.
2014-04-04 18:20:22 +03:00
Alvaro Herrera f88d4cfc9d Setup error context callback for transaction lock waits
With this in place, a session blocking behind another one because of
tuple locks will get a context line mentioning the relation name, tuple
TID, and operation being done on tuple.  For example:

LOG:  process 11367 still waiting for ShareLock on transaction 717 after 1000.108 ms
DETAIL:  Process holding the lock: 11366. Wait queue: 11367.
CONTEXT:  while updating tuple (0,2) in relation "foo"
STATEMENT:  UPDATE foo SET value = 3;

Most usefully, the new line is displayed by log entries due to
log_lock_waits, although of course it will be printed by any other log
message as well.

Author: Christian Kruse, some tweaks by Álvaro Herrera
Reviewed-by: Amit Kapila, Andres Freund, Tom Lane, Robert Haas
2014-03-19 15:10:36 -03:00
Heikki Linnakangas a3115f0d9e Only WAL-log the modified portion in an UPDATE, if possible.
When a row is updated, and the new tuple version is put on the same page as
the old one, only WAL-log the part of the new tuple that's not identical to
the old. This saves significantly on the amount of WAL that needs to be
written, in the common case that most fields are not modified.

Amit Kapila, with a lot of back and forth with me, Robert Haas, and others.
2014-03-12 23:28:36 +02:00
Robert Haas b89e151054 Introduce logical decoding.
This feature, building on previous commits, allows the write-ahead log
stream to be decoded into a series of logical changes; that is,
inserts, updates, and deletes and the transactions which contain them.
It is capable of handling decoding even across changes to the schema
of the effected tables.  The output format is controlled by a
so-called "output plugin"; an example is included.  To make use of
this in a real replication system, the output plugin will need to be
modified to produce output in the format appropriate to that system,
and to perform filtering.

Currently, information can be extracted from the logical decoding
system only via SQL; future commits will add the ability to stream
changes via walsender.

Andres Freund, with review and other contributions from many other
people, including Álvaro Herrera, Abhijit Menon-Sen, Peter Gheogegan,
Kevin Grittner, Robert Haas, Heikki Linnakangas, Fujii Masao, Abhijit
Menon-Sen, Michael Paquier, Simon Riggs, Craig Ringer, and Steve
Singer.
2014-03-03 16:32:18 -05:00
Alvaro Herrera 6bfa88acd3 Fix WAL replay of locking an updated tuple
We were resetting the tuple's HEAP_HOT_UPDATED flag as well as t_ctid on
WAL replay of a tuple-lock operation, which is incorrect when the tuple
is already updated.

Back-patch to 9.3.  The clearing of both header elements was there
previously, but since no update could be present on a tuple that was
being locked, it was harmless.

Bug reported by Peter Geoghegan and Greg Stark in
CAM3SWZTMQiCi5PV5OWHb+bYkUcnCk=O67w0cSswPvV7XfUcU5g@mail.gmail.com and
CAM-w4HPTOeMT4KP0OJK+mGgzgcTOtLRTvFZyvD0O4aH-7dxo3Q@mail.gmail.com
respectively; diagnosis by Andres Freund.
2014-02-27 11:13:39 -03:00
Alvaro Herrera 423e1211a8 Accept pg_upgraded tuples during multixact freezing
The new MultiXact freezing routines introduced by commit 8e9a16ab8f
neglected to consider tuples that came from a pg_upgrade'd database; a
vacuum run that tried to freeze such tuples would die with an error such
as
ERROR: MultiXactId 11415437 does no longer exist -- apparent wraparound

To fix, ensure that GetMultiXactIdMembers is allowed to return empty
multis when the infomask bits are right, as is done in other callsites.

Per trouble report from F-Secure.

In passing, fix a copy&paste bug reported by Andrey Karpov from VIVA64
from their PVS-Studio static checked, that instead of setting relminmxid
to Invalid, we were setting relfrozenxid twice.  Not an important
mistake because that code branch is about relations for which we don't
use the frozenxid/minmxid values at all in the first place, but seems to
warrants a fix nonetheless.
2014-01-10 18:03:18 -03:00
Bruce Momjian 7e04792a1c Update copyright for 2014
Update all files in head, and files COPYRIGHT and legal.sgml in all back
branches.
2014-01-07 16:05:30 -05:00
Robert Haas 37484ad2aa Change the way we mark tuples as frozen.
Instead of changing the tuple xmin to FrozenTransactionId, the combination
of HEAP_XMIN_COMMITTED and HEAP_XMIN_INVALID, which were previously never
set together, is now defined as HEAP_XMIN_FROZEN.  A variety of previous
proposals to freeze tuples opportunistically before vacuum_freeze_min_age
is reached have foundered on the objection that replacing xmin by
FrozenTransactionId might hinder debugging efforts when things in this
area go awry; this patch is intended to solve that problem by keeping
the XID around (but largely ignoring the value to which it is set).

Third-party code that checks for HEAP_XMIN_INVALID on tuples where
HEAP_XMIN_COMMITTED might be set will be broken by this change.  To fix,
use the new accessor macros in htup_details.h rather than consulting the
bits directly.  HeapTupleHeaderGetXmin has been modified to return
FrozenTransactionId when the infomask bits indicate that the tuple is
frozen; use HeapTupleHeaderGetRawXmin when you already know that the
tuple isn't marked commited or frozen, or want the raw value anyway.
We currently do this in routines that display the xmin for user consumption,
in tqual.c where it's known to be safe and important for the avoidance of
extra cycles, and in the function-caching code for various procedural
languages, which shouldn't invalidate the cache just because the tuple
gets frozen.

Robert Haas and Andres Freund
2013-12-22 15:49:09 -05:00
Alvaro Herrera 13aa624431 Optimize updating a row that's locked by same xid
Updating or locking a row that was already locked by the same
transaction under the same Xid caused a MultiXact to be created; but
this is unnecessary, because there's no usefulness in being able to
differentiate two locks by the same transaction.  In particular, if a
transaction executed SELECT FOR UPDATE followed by an UPDATE that didn't
modify columns of the key, we would dutifully represent the resulting
combination as a multixact -- even though a single key-update is
sufficient.

Optimize the case so that only the strongest of both locks/updates is
represented in Xmax.  This can save some Xmax's from becoming
MultiXacts, which can be a significant optimization.

This missed optimization opportunity was spotted by Andres Freund while
investigating a bug reported by Oliver Seemann in message
CANCipfpfzoYnOz5jj=UZ70_R=CwDHv36dqWSpwsi27vpm1z5sA@mail.gmail.com
and also directly as a performance regression reported by Dong Ye in
message
d54b8387.000012d8.00000010@YED-DEVD1.vmware.com
Reportedly, this patch fixes the performance regression.

Since the missing optimization was reported as a significant performance
regression from 9.2, backpatch to 9.3.

Andres Freund, tweaked by Álvaro Herrera
2013-12-19 16:53:49 -03:00
Alvaro Herrera 3b97e6823b Rework tuple freezing protocol
Tuple freezing was broken in connection to MultiXactIds; commit
8e53ae025d tried to fix it, but didn't go far enough.  As noted by
Noah Misch, freezing a tuple whose Xmax is a multi containing an aborted
update might cause locks in the multi to go ignored by later
transactions.  This is because the code depended on a multixact above
their cutoff point not having any lock-only member older than the cutoff
point for Xids, which is easily defeated in READ COMMITTED transactions.

The fix for this involves creating a new MultiXactId when necessary.
But this cannot be done during WAL replay, and moreover multixact
examination requires using CLOG access routines which are not supposed
to be used during WAL replay either; so tuple freezing cannot be done
with the old freeze WAL record.  Therefore, separate the freezing
computation from its execution, and change the WAL record to carry all
necessary information.  At WAL replay time, it's easy to re-execute
freezing because we don't need to re-compute the new infomask/Xmax
values but just take them from the WAL record.

While at it, restructure the coding to ensure all page changes occur in
a single critical section without much room for failures.  The previous
coding wasn't using a critical section, without any explanation as to
why this was acceptable.

In replication scenarios using the 9.3 branch, standby servers must be
upgraded before their master, so that they are prepared to deal with the
new WAL record once the master is upgraded; failure to do so will cause
WAL replay to die with a PANIC message.  Later upgrade of the standby
will allow the process to continue where it left off, so there's no
disruption of the data in the standby in any case.  Standbys know how to
deal with the old WAL record, so it's okay to keep the master running
the old code for a while.

In master, the old freeze WAL record is gone, for cleanliness' sake;
there's no compatibility concern there.

Backpatch to 9.3, where the original bug was introduced and where the
previous fix was backpatched.

Álvaro Herrera and Andres Freund
2013-12-16 11:29:50 -03:00
Heikki Linnakangas 50e547096c Add GUC to enable WAL-logging of hint bits, even with checksums disabled.
WAL records of hint bit updates is useful to tools that want to examine
which pages have been modified. In particular, this is required to make
the pg_rewind tool safe (without checksums).

This can also be used to test how much extra WAL-logging would occur if
you enabled checksums, without actually enabling them (which you can't
currently do without re-initdb'ing).

Sawada Masahiko, docs by Samrat Revagade. Reviewed by Dilip Kumar, with
further changes by me.
2013-12-13 16:26:14 +02:00
Robert Haas 60dd40bbda Under wal_level=logical, when saving old tuples, always save OID.
There's no real point in not doing this.  It doesn't cost anything
in performance or space.  So let's go wild.

Andres Freund, with substantial editing as to style by me.
2013-12-11 13:19:31 -05:00