The code previously relied on "long" as type to track block numbers,
which would be 4 bytes in all Windows builds or any 32-bit builds. This
limited the code to be able to handle up to 16TB of data with the
default block size of 8kB, like during a CLUSTER. This code now relies
on a more portable int64, which should be more than enough for at least
the next 20 years to come.
This issue has been reported back in 2017, but nothing was done about it
back then, so here we go now.
Reported-by: Peter Geoghegan
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/CAH2-WznCscXnWmnj=STC0aSa7QG+BRedDnZsP=Jo_R9GUZvUrg@mail.gmail.com
nFreeBlocks, defined as a long, stores the number of free blocks in a
logical tape. ltsGetFreeBlock() has been using an int to store the
value of nFreeBlocks, which could lead to overflows on platforms where
long and int are not the same size (in short everything except Windows
where long is 4 bytes).
The problematic intermediate variable is switched to be a long instead
of an int.
Issue introduced by c02fdc9223, so backpatch down to 13.
Author: Ranier vilela
Reviewed-by: Peter Geoghegan, David Rowley
Discussion: https://postgr.es/m/CAEudQApLDWCBR_xmwNjGBrDo+f+S4E87x3s7-+hoaKqYdtC4JQ@mail.gmail.com
Backpatch-through: 13
In order to have the option to use O_DIRECT/FILE_FLAG_NO_BUFFERING in a
later commit, we need the addresses of user space buffers to be well
aligned. The exact requirements vary by OS and file system (typically
sectors and/or memory pages). The address alignment size is set to
4096, which is enough for currently known systems: it matches modern
sectors and common memory page size. There is no standard governing
O_DIRECT's requirements so we might eventually have to reconsider this
with more information from the field or future systems.
Aligning I/O buffers on memory pages is also known to improve regular
buffered I/O performance.
Three classes of I/O buffers for regular data pages are adjusted:
(1) Heap buffers are now allocated with the new palloc_aligned() or
MemoryContextAllocAligned() functions introduced by commit 439f6175.
(2) Stack buffers now use a new struct PGIOAlignedBlock to respect
PG_IO_ALIGN_SIZE, if possible with this compiler. (3) The buffer
pool is also aligned in shared memory.
WAL buffers were already aligned on XLOG_BLCKSZ. It's possible for
XLOG_BLCKSZ to be configured smaller than PG_IO_ALIGNED_SIZE and thus
for O_DIRECT WAL writes to fail to be well aligned, but that's a
pre-existing condition and will be addressed by a later commit.
BufFiles are not yet addressed (there's no current plan to use O_DIRECT
for those, but they could potentially get some incidental speedup even
in plain buffered I/O operations through better alignment).
If we can't align stack objects suitably using the compiler extensions
we know about, we disable the use of O_DIRECT by setting PG_O_DIRECT to
0. This avoids the need to consider systems that have O_DIRECT but
can't align stack objects the way we want; such systems could in theory
be supported with more work but we don't currently know of any such
machines, so it's easier to pretend there is no O_DIRECT support
instead. That's an existing and tested class of system.
Add assertions that all buffers passed into smgrread(), smgrwrite() and
smgrextend() are correctly aligned, unless PG_O_DIRECT is 0 (= stack
alignment tricks may be unavailable) or the block size has been set too
small to allow arrays of buffers to be all aligned.
Author: Thomas Munro <thomas.munro@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/CA+hUKGK1X532hYqJ_MzFWt0n1zt8trz980D79WbjwnT-yYLZpg@mail.gmail.com
Commit c4649cce39 removed the "shared" and "ntapes" arguments, but the
comment still talked about "shared". It also talked about "a shared
file handle", which was technically correct because even before commit
c4649cce39, the "shared file handle" referred to the "fileset"
argument, not "shared". But it was very confusing. Improve the
comment.
Also add a comment on what the "preallocate" argument does.
Backpatch to v15, just to make backpatching other patches easier in
the future.
Discussion: https://www.postgresql.org/message-id/af989685-91d5-aad4-8f60-1d066b5ec309@enterprisedb.com
Reviewed-by: Peter Eisentraut
Most callers of BufFileRead() want to check whether they read the full
specified length. Checking this at every call site is very tedious.
This patch provides additional variants BufFileReadExact() and
BufFileReadMaybeEOF() that include the length checks.
I considered changing BufFileRead() itself, but this function is also
used in extensions, and so changing the behavior like this would
create a lot of problems there. The new names are analogous to the
existing LogicalTapeReadExact().
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/f3501945-c591-8cc3-5ef0-b72a2e0eaa9c@enterprisedb.com
Borrow the logic that's long been used in tuplesort.c: instead
of physically swapping the data in two heap entries, keep the
value that's being sifted up or down in a local variable, and
just move the other values as necessary. This makes the code
shorter as well as faster. It's not clear that any current
callers are really time-critical enough to notice, but we
might as well code heap maintenance the same way everywhere.
Ma Liangzhu and Tom Lane
Discussion: https://postgr.es/m/17336-fc4e522d26a750fd@postgresql.org
This could only matter if (a) long is wider than int, and (b) the heap
of free blocks exceeds UINT_MAX entries, which seems pretty unlikely.
Still, it's a theoretical bug, so backpatch to v13 where the typo came
in (in commit c02fdc922).
In passing, also make swap_nodes() use consistent datatypes.
Ma Liangzhu
Discussion: https://postgr.es/m/17336-fc4e522d26a750fd@postgresql.org
All the tape functions, like LogicalTapeRead and LogicalTapeWrite, now
take a LogicalTape as argument, instead of LogicalTapeSet+tape number.
You can create any number of LogicalTapes in a single LogicalTapeSet, and
you don't need to decide the number upfront, when you create the tape set.
This makes the tape management in hash agg spilling in nodeAgg.c simpler.
Discussion: https://www.postgresql.org/message-id/420a0ec7-602c-d406-1e75-1ef7ddc58d83%40iki.fi
Reviewed-by: Peter Geoghegan, Zhihong Yu, John Naylor
Use one fileset for the entire worker lifetime instead of using
separate filesets for each streaming transaction. Now, the
changes/subxacts files for every streaming transaction will be
created under the same fileset and the files will be deleted
after the transaction is completed.
This patch extends the BufFileOpenFileSet and BufFileDeleteFileSet
APIs to allow users to specify whether to give an error on missing
files.
Author: Dilip Kumar, based on suggestion by Thomas Munro
Reviewed-by: Hou Zhijie, Masahiko Sawada, Amit Kapila
Discussion: https://postgr.es/m/E1mCC6U-0004Ik-Fs@gemulon.postgresql.org
Move fileset related implementation out of sharedfileset.c to allow its
usage by backends that don't want to share filesets among different
processes. After this split, fileset infrastructure is used by both
sharedfileset.c and worker.c for the named temporary files that survive
across transactions.
Author: Dilip Kumar, based on suggestion by Andres Freund
Reviewed-by: Hou Zhijie, Masahiko Sawada, Amit Kapila
Discussion: https://postgr.es/m/E1mCC6U-0004Ik-Fs@gemulon.postgresql.org
Also "make reformat-dat-files".
The only change worthy of note is that pgindent messed up the formatting
of launcher.c's struct LogicalRepWorkerId, which led me to notice that
that struct wasn't used at all anymore, so I just took it out.
Previously, it was based on nBlocksAllocated to account for tapes with
open write buffers that may not have made it to the BufFile yet.
That was unnecessary, because callers do not need to get the number of
blocks while a tape has an open write buffer; and it also conflicted
with the preallocation logic added for HashAgg.
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/ce5af05900fdbd0e9185747825a7423c48501964.camel@j-davis.com
Backpatch-through: 13
Allow BufFile to support temporary files that can be used by the single
backend when the corresponding files need to be survived across the
transaction and need to be opened and closed multiple times. Such files
need to be created as a member of a SharedFileSet.
Additionally, this commit implements the interface for BufFileTruncate to
allow files to be truncated up to a particular offset and extends the
BufFileSeek API to support the SEEK_END case. This also adds an option to
provide a mode while opening the shared BufFiles instead of always opening
in read-only mode.
These enhancements in BufFile interface are required for the upcoming
patch to allow the replication apply worker, to handle streamed
in-progress transactions.
Author: Dilip Kumar, Amit Kapila
Reviewed-by: Amit Kapila
Tested-by: Neha Sharma
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com
Convert buffile.c error handling to use ereport. This fixes cases where
I/O errors were indistinguishable from EOF or not reported. Also remove
"%m" from error messages where errno would be bogus. While we're
modifying those strings, add block numbers and short read byte counts
where appropriate.
Back-patch to all supported releases.
Reported-by: Amit Khandekar <amitdkhan.pg@gmail.com>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CA%2BhUKGJE04G%3D8TLK0DLypT_27D9dR8F1RQgNp0jK6qR0tZGWOw%40mail.gmail.com
Commit 24d85952 made a change that indirectly caused a performance
regression by triggering a change in the way GCC optimizes memcpy() on
some platforms.
The behavior seemed to contradict a GCC document, so I filed a report:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95556
This patch implements a narrow workaround which eliminates the
regression I observed. The workaround is benign enough that it seems
unlikely to cause a different regression on another platform.
Discussion: https://postgr.es/m/99b2eab335c1592c925d8143979c8e9e81e1575f.camel@j-davis.com
Disk-based HashAgg relies on writing to multiple tapes
concurrently. Avoid fragmentation of the tapes' blocks by
preallocating many blocks for a tape at once. No file operations are
performed during preallocation; only the block numbers are reserved.
Reviewed-by: Tomas Vondra
Discussion: https://postgr.es/m/20200519151202.u2p2gpiawoaznsv2%40development
Includes some manual cleanup of places that pgindent messed up,
most of which weren't per project style anyway.
Notably, it seems some people didn't absorb the style rules of
commit c9d297751, because there were a bunch of new occurrences
of function calls with a newline just after the left paren, all
with faulty expectations about how the rest of the call would get
indented.
Increases the number of tapes in a logical tape set. This will be
important for disk-based hash aggregation, because the maximum number
of tapes is not known ahead of time.
While discussing this change, it was observed to regress the
performance of Sort for at least one test case. The performance
regression was because some versions of GCC switch to an inlined
version of memcpy() in LogicalTapeWrite() after this change. No
performance regression for clang was observed.
Because the regression is due to an arbitrary decision by the
compiler, I decided it shouldn't hold up this change. If it needs to
be fixed, we can find a workaround.
Author: Adam Lee, Jeff Davis
Discussion: https://postgr.es/m/e54bfec11c59689890f277722aaaabd05f78e22c.camel%40j-davis.com
Prior to this commit, the read buffer was allocated at the time the tape
was rewound; but as an optimization, would not be allocated at all if
the tape was empty.
That optimization meant that it was valid to have a rewound tape with
the buffer set to NULL, but only if a number of conditions were met
and only if the API was used properly. After 7fdd919a refactored the
code to support lazily-allocating the buffer, Coverity started
complaining.
The optimization for empty tapes doesn't seem important, so just
allocate the buffer whether the tape has any data or not.
Discussion: https://postgr.es/m/20351.1581868306%40sss.pgh.pa.us
Move the responsibility for checking for and reporting a failure from
the only current BufFileSize() caller, logtape.c, to BufFileSize()
itself. Code within buffile.c is generally responsible for interfacing
with fd.c to report irrecoverable failures. This seems like a
convention that's worth sticking to.
Reorganizing things this way makes it easy to make the error message
raised in the event of BufFileSize() failure descriptive of the
underlying problem. We're now clear on the distinction between
temporary file name and BufFile name, and can show errno, confident that
its value actually relates to the error being reported. In passing, an
existing, similar buffile.c ereport() + errcode_for_file_access() site
is changed to follow the same conventions.
The API of the function BufFileSize() is changed by this commit, despite
already being in a stable release (Postgres 11). This seems acceptable,
since the BufFileSize() ABI was changed by commit aa55183042, which
hasn't made it into a point release yet. Besides, it's difficult to
imagine a third party BufFileSize() caller not just raising an error
anyway, since BufFile state should be considered corrupt when
BufFileSize() fails.
Per complaint from Tom Lane.
Discussion: https://postgr.es/m/26974.1540826748@sss.pgh.pa.us
Backpatch: 11-, where shared BufFiles were introduced.
BufFileSize() can't use off_t, because it's only 32 bits wide on
some systems. BufFile objects can have many 1GB segments so the
total size can exceed 2^31. The only known client of the function
is parallel CREATE INDEX, which was reported to fail when building
large indexes on Windows.
Though this is technically an ABI break on platforms with a 32 bit
off_t and we might normally avoid back-patching it, the function is
brand new and thus unlikely to have been discovered by extension
authors yet, and it's fairly thoroughly broken on those platforms
anyway, so just fix it.
Defect in 9da0cc35. Bug #15460. Back-patch to 11, where this
function landed.
Author: Thomas Munro
Reported-by: Paul van der Linden, Pavel Oskin
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/15460-b6db80de822fa0ad%40postgresql.org
Discussion: https://postgr.es/m/CAHDGBJP_GsESbTt4P3FZA8kMUKuYxjg57XHF7NRBoKnR%3DCAR-g%40mail.gmail.com
There's a project policy against using plain "char buf[BLCKSZ]" local
or static variables as page buffers; preferred style is to palloc or
malloc each buffer to ensure it is MAXALIGN'd. However, that policy's
been ignored in an increasing number of places. We've apparently got
away with it so far, probably because (a) relatively few people use
platforms on which misalignment causes core dumps and/or (b) the
variables chance to be sufficiently aligned anyway. But this is not
something to rely on. Moreover, even if we don't get a core dump,
we might be paying a lot of cycles for misaligned accesses.
To fix, invent new union types PGAlignedBlock and PGAlignedXLogBlock
that the compiler must allocate with sufficient alignment, and use
those in place of plain char arrays.
I used these types even for variables where there's no risk of a
misaligned access, since ensuring proper alignment should make
kernel data transfers faster. I also changed some places where
we had been palloc'ing short-lived buffers, for coding style
uniformity and to save palloc/pfree overhead.
Since this seems to be a live portability hazard (despite the lack
of field reports), back-patch to all supported versions.
Patch by me; thanks to Michael Paquier for review.
Discussion: https://postgr.es/m/1535618100.1286.3.camel@credativ.de
randomAccess parallel tuplesorts are disallowed because the leader would
try to write to its own leader tape, not because the leader would try to
write to a worker tape directly.
Cleanup from commit 9da0cc3528.
There were three related issues:
* BufFileAppend() incorrectly reset the seek position on the 'source' file.
As a result, if you had called BufFileRead() on the file before calling
BufFileAppend(), it got confused, and subsequent calls would read/write
at wrong position.
* BufFileSize() did not work with files opened with BufFileOpenShared().
* FileGetSize() only worked on temporary files.
To fix, change the way BufFileSize() works so that it works on shared
files. Remove FileGetSize() altogether, as it's no longer needed. Remove
buffilesize from TapeShare struct, as the leader process can simply call
BufFileSize() to get the tape's size, there's no need to pass it through
shared memory anymore.
Discussion: https://www.postgresql.org/message-id/CAH2-WznEDYe_NZXxmnOfsoV54oFkTdMy7YLE2NPBLuttO96vTQ@mail.gmail.com
Commit b75f467b6e removed the LogicalTapeAssignReadBufferSize() function,
but forgot to update this comment. The read buffer size is an argument to
LogicalTapeRewindForRead() now. Doesn't seem worth going into the details
in the file header comment, so remove the outdated sentence altogether.
All of these are false positives, but in each case a fair amount of
analysis is needed to see that, and it's not too surprising that not all
compilers are smart enough. (In particular, in the logtape.c case, a
compiler lacking the knowledge provided by the Assert would almost surely
complain, so that this warning will be seen in any non-assert build.)
Some of these are of long standing while others are pretty recent,
but it only seems worth fixing them in HEAD.
Jaime Casanova, tweaked a bit by me
Discussion: https://postgr.es/m/CAJGNTeMcYAMJdPAom52dppLMtF-UnEZi0dooj==75OEv1EoBZA@mail.gmail.com
LogicalTapeFreeze() may write out its first block when it is dirty but
not full, and then immediately read the first block back in from its
BufFile as a BLCKSZ-width block. This can only occur in rare cases
where very few tuples were written out, which is currently only
possible with parallel external tuplesorts. To avoid valgrind
complaints, tell it to treat the tail of logtape.c's buffer as
defined.
Commit 9da0cc3528 exposed this problem
but did not create it. LogicalTapeFreeze() has always tended to write
out some amount of garbage bytes, but previously never wrote less than
one block of data in total, so the problem was masked.
Per buildfarm members lousyjack and skink.
Peter Geoghegan, based on a suggestion from Tom Lane and me. Some
comment revisions by me.
To make this work, tuplesort.c and logtape.c must also support
parallelism, so this patch adds that infrastructure and then applies
it to the particular case of parallel btree index builds. Testing
to date shows that this can often be 2-3x faster than a serial
index build.
The model for deciding how many workers to use is fairly primitive
at present, but it's better than not having the feature. We can
refine it as we get more experience.
Peter Geoghegan with some help from Rushabh Lathia. While Heikki
Linnakangas is not an author of this patch, he wrote other patches
without which this feature would not have been possible, and
therefore the release notes should possibly credit him as an author
of this feature. Reviewed by Claudio Freire, Heikki Linnakangas,
Thomas Munro, Tels, Amit Kapila, me.
Discussion: http://postgr.es/m/CAM3SWZQKM=Pzc=CAHzRixKjp2eO5Q0Jg1SoFQqeXFQ647JiwqQ@mail.gmail.com
Discussion: http://postgr.es/m/CAH2-Wz=AxWqDoVvGU7dq856S4r6sJAj6DBn7VMtigkB33N5eyg@mail.gmail.com
Don't move parenthesized lines to the left, even if that means they
flow past the right margin.
By default, BSD indent lines up statement continuation lines that are
within parentheses so that they start just to the right of the preceding
left parenthesis. However, traditionally, if that resulted in the
continuation line extending to the right of the desired right margin,
then indent would push it left just far enough to not overrun the margin,
if it could do so without making the continuation line start to the left of
the current statement indent. That makes for a weird mix of indentations
unless one has been completely rigid about never violating the 80-column
limit.
This behavior has been pretty universally panned by Postgres developers.
Hence, disable it with indent's new -lpl switch, so that parenthesized
lines are always lined up with the preceding left paren.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4d wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
The "Simplify tape block format" commit ignored the rule that blocks
returned by ltsGetFreeBlock() must be written out in the same order, at
least in the first write pass. To fix, relax that requirement, by making
ltsWriteBlock() to detect if it's about to create a "hole" in the
underlying BufFile, and fill it with zeros instead.
Reported, analysed, and reviewed by Peter Geoghegan.
Discussion: https://www.postgresql.org/message-id/CAM3SWZRWdNtkhiG0GyiX_1mUAypiK3dV6-6542pYe2iEL-foTA@mail.gmail.com
Bruce Momjian
Michael Paquier
Thomas Munro
Heikki Linnakangas
Peter Eisentraut
Tom Lane
Amit Kapila
Jeff Davis
Peter Geoghegan
Robert Haas