4035cd5d4e
The logic is implemented so as there can be a choice in the compression used when building a WAL record, and an extra per-record bit is used to track down if a block is compressed with PGLZ, LZ4 or nothing. wal_compression, the existing parameter, is changed to an enum with support for the following backward-compatible values: - "off", the default, to not use compression. - "pglz" or "on", to compress FPWs with PGLZ. - "lz4", the new mode, to compress FPWs with LZ4. Benchmarking has showed that LZ4 outclasses easily PGLZ. ZSTD would be also an interesting choice, but going just with LZ4 for now makes the patch minimalistic as toast compression is already able to use LZ4, so there is no need to worry about any build-related needs for this implementation. Author: Andrey Borodin, Justin Pryzby Reviewed-by: Dilip Kumar, Michael Paquier Discussion: https://postgr.es/m/3037310D-ECB7-4BF1-AF20-01C10BB33A33@yandex-team.ru |
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| .. | ||
| activity | ||
| adt | ||
| cache | ||
| error | ||
| fmgr | ||
| hash | ||
| init | ||
| mb | ||
| misc | ||
| mmgr | ||
| resowner | ||
| sort | ||
| time | ||
| .gitignore | ||
| Gen_dummy_probes.pl | ||
| Gen_dummy_probes.pl.prolog | ||
| Gen_dummy_probes.sed | ||
| Gen_fmgrtab.pl | ||
| Makefile | ||
| README.Gen_dummy_probes | ||
| errcodes.txt | ||
| generate-errcodes.pl | ||
| probes.d | ||
README.Gen_dummy_probes
# Generating dummy probes If Postgres isn't configured with dtrace enabled, we need to generate dummy probes for the entries in probes.d, that do nothing. This is accomplished in Unix via the sed script `Gen_dummy_probes.sed`. We used to use this in MSVC builds using the perl utility `psed`, which mimicked sed. However, that utility disappeared from Windows perl distributions and so we converted the sed script to a perl script to be used in MSVC builds. We still keep the sed script as the authoritative source for generating these dummy probes because except on Windows perl is not a hard requirement when building from a tarball. So, if you need to change the way dummy probes are generated, first change the sed script, and when it's working generate the perl script. This can be accomplished by using the perl utility s2p. s2p is no longer part of the perl core, so it might not be on your system, but it is available on CPAN and also in many package systems. e.g. on Fedora it can be installed using `cpan App::s2p` or `dnf install perl-App-s2p`. The Makefile contains a recipe for regenerating Gen_dummy_probes.pl, so all you need to do is once you have s2p installed is `make Gen_dummy_probes.pl` Note that in a VPATH build this will generate the file in the vpath tree, not the source tree.