Before this patch, there was some code that tried to make sure that the
buffer was always big enough at the start, and then asserted that it
didn't need to be enlarged later. However, the code to make sure it was
big enough at the start doesn't actually work, and therefore it was
possible to fail an assertion and crash later.
Remove the code that tries to make sure the buffer is always big enough
at the start in favor of enlarging the buffer as we go along whenever
that is necessary.
The mistake probably happened because, on the server side, we do
actually need to guarantee that the buffer is big enough at the start
to avoid subsequent resizings. However, in that case, the calling
code makes promises about how much data it will provide at once, but
here, that's not the case.
Report by Justin Pryzby. Analysis by me. Patch by Dipesh Pandit.
Discussion: http://postgr.es/m/20220330143536.GG28503@telsasoft.com
When we try to set the zstd compression level either on the client
or on the server, check for errors.
For any algorithm, on the client side, don't try to set the compression
level unless the user specified one. This was visibly broken for
zstd, which managed to set -1 rather than 0 in this case, but tidy
up the code for the other methods, too.
On the client side, if we fail to create a ZSTD_CCtx, exit after
reporting the error. Otherwise we'll dereference a null pointer.
Patch by me, reviewed by Dipesh Pandit.
Discussion: http://postgr.es/m/CA+TgmoZK3zLQUCGi1h4XZw4jHiAWtcACc+GsdJR1_Mc19jUjXA@mail.gmail.com
There are more compression parameters that can be specified than just
an integer compression level, so rename the new COMPRESSION_LEVEL
option to COMPRESSION_DETAIL before it gets released. Introduce a
flexible syntax for that option to allow arbitrary options to be
specified without needing to adjust the main replication grammar,
and common code to parse it that is shared between the client and
the server.
This commit doesn't actually add any new compression parameters,
so the only user-visible change is that you can now type something
like pg_basebackup --compress gzip:level=5 instead of writing just
pg_basebackup --compress gzip:5. However, it should make it easy to
add new options. If for example gzip starts offering fries, we can
support pg_basebackup --compress gzip:level=5,fries=true for the
benefit of users who want fries with that.
Along the way, this fixes a few things in pg_basebackup so that the
pg_basebackup can be used with a server-side compression algorithm
that pg_basebackup itself does not understand. For example,
pg_basebackup --compress server-lz4 could still succeed even if
only the server and not the client has LZ4 support, provided that
the other options to pg_basebackup don't require the client to
decompress the archive.
Patch by me. Reviewed by Justin Pryzby and Dagfinn Ilmari Mannsåker.
Discussion: http://postgr.es/m/CA+TgmoYvpetyRAbbg1M8b3-iHsaN4nsgmWPjOENu5-doHuJ7fA@mail.gmail.com
These tests were added recently, but older code tests USE_LZ4 rathr
than HAVE_LIBLZ4, so let's follow the established precedent. It
also seems more consistent with the intent of the configure tests,
since I think that the USE_* symbols are intended to correspond to
what the user requested, and the HAVE_* symbols to what configure
found while probing.
Discussion: http://postgr.es/m/CA+Tgmoap+hTD2-QNPJLH4tffeFE8MX5+xkbFKMU3FKBy=ZSNKA@mail.gmail.com
LZ4 compression can now be performed on the client using
pg_basebackup -Ft --compress client-lz4, and LZ4 decompression of
a backup compressed on the server can be performed on the client
using pg_basebackup -Fp --compress server-lz4.
Dipesh Pandit, reviewed and tested by Jeevan Ladhe and Tushar Ahuja,
with a few corrections - and some documentation - by me.
Discussion: http://postgr.es/m/CAN1g5_FeDmiA9D8wdG2W6Lkq5CpubxOAqTmd2et9hsinTJtsMQ@mail.gmail.com