Re: adding 'zstd' as a compression algorithm (initdb/lz4)

On Tue, Feb 15, 2022 at 11:54:10AM -0800, Andres Freund wrote:
> > Isn't it an incontrovertible fact that LZ4 is superior to pglz in
> > every way? LZ4 is pretty much its successor. And so it seems totally
> > fine to assume that users will always want to use the clearly better
> > option, and that that option will be generally available going
> > forward. TOAST compression is applied selectively already, based on
> > various obscure implementation details, some of which are quite
> > arbitrary.
>
> Yea, we should really default to lz4 in initdb when available.

This patch intends to implement that. I have no particular interest in this,
but if anyone wants, I will add it to the next CF (or the one after that).

commit 2a3c5950e625ccfaebc49bbf71b8db16dc143cd2
Author: Justin Pryzby <pryzbyj(at)telsasoft(dot)com>
Date: Tue Feb 15 19:14:33 2022 -0600

initdb: default_toast_compression=lz4 if available

TODO: consider same for wal_compression

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc63172efde..f9cd2ef7229 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -8537,7 +8537,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The supported compression methods are <literal>pglz</literal> and
(if <productname>PostgreSQL</productname> was compiled with
<option>--with-lz4</option>) <literal>lz4</literal>.
- The default is <literal>pglz</literal>.
+ The default is <literal>lz4</literal> if available at the time
+ <productname>PostgreSQL</productname> was compiled, otherwise
+ <literal>pglz</literal>.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f505413a7f9..6b6f6efaba1 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4726,7 +4726,11 @@ static struct config_enum ConfigureNamesEnum[] =
NULL
},
&default_toast_compression,
+#ifdef USE_LZ4
+ TOAST_LZ4_COMPRESSION,
+#else
TOAST_PGLZ_COMPRESSION,
+#endif
default_toast_compression_options,
NULL, NULL, NULL
},
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index d78e8e67b8d..bb7c57e00fa 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1185,6 +1185,12 @@ setup_config(void)
"#update_process_title = off");
#endif

+#ifdef USE_LZ4
+ conflines = replace_token(conflines,
+ "#default_toast_compression = 'pglz'",
+ "#default_toast_compression = 'lz4'");
+#endif
+
/*
* Change password_encryption setting to md5 if md5 was chosen as an
* authentication method, unless scram-sha-256 was also chosen.