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Server-side gzip compression.

pg_basebackup's --compression option now lets you write either
"client-gzip" or "server-gzip" instead of just "gzip" to specify
where the compression should be performed. If you write simply
"gzip" it's taken to mean "client-gzip" unless you also use
--target, in which case it is interpreted to mean "server-gzip",
because that's the only thing that makes any sense in that case.

To make this work, the BASE_BACKUP command now takes new
COMPRESSION and COMPRESSION_LEVEL options.

At present, pg_basebackup cannot decompress .gz files, so
server-side compression will cause a failure if (1) -Ft is not
used or (2) -R is used or (3) -D- is used without --no-manifest.

Along the way, I removed the information message added by commit
5c649fe153 which occurred if you
specified no compression level and told you that the default level
had been used instead. That seemed like more output than most
people would want.

Also along the way, this adds a check to the server for
unrecognized base backup options. This repairs a bug introduced
by commit 0ba281cb4b.

This commit also adds some new test cases for pg_verifybackup.
They take a server-side backup with and without compression, and
then extract the backup if we have the OS facilities available
to do so, and then run pg_verifybackup on the extracted
directory. That is a good test of the functionality added by
this commit and also improves test coverage for the backup target
patch (commit 3500ccc39b) and for
pg_verifybackup itself.

Patch by me, with a bug fix by Jeevan Ladhe.  The patch set of which
this is a part has also had review and/or testing from Tushar Ahuja,
Suraj Kharage, Dipesh Pandit, and Mark Dilger.

Discussion: http://postgr.es/m/CA+Tgmoa-ST7fMLsVJduOB7Eub=2WjfpHS+QxHVEpUoinf4bOSg@mail.gmail.com
This commit is contained in:
Robert Haas
2022-01-24 15:13:18 -05:00
parent aa01051418
commit 0ad8032910
10 changed files with 641 additions and 24 deletions

View File

@ -2719,6 +2719,28 @@ The commands accepted in replication mode are:
</listitem>
</varlistentry>
<varlistentry>
<term><literal>COMPRESSION</literal> <replaceable>'method'</replaceable></term>
<listitem>
<para>
Instructs the server to compress the backup using the specified
method. Currently, the only supported method is
<literal>gzip</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>COMPRESSION_LEVEL</literal> <replaceable>level</replaceable></term>
<listitem>
<para>
Specifies the compression level to be used. This should only be
used in conjunction with the <literal>COMPRESSION</literal> option.
The value should be an integer between 1 and 9.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>MAX_RATE</literal> <replaceable>rate</replaceable></term>
<listitem>

View File

@ -400,21 +400,36 @@ PostgreSQL documentation
<term><option>-Z <replaceable class="parameter">level</replaceable></option></term>
<term><option>-Z <replaceable class="parameter">method</replaceable></option>[:<replaceable>level</replaceable>]</term>
<term><option>--compress=<replaceable class="parameter">level</replaceable></option></term>
<term><option>--compress=<replaceable class="parameter">method</replaceable></option>[:<replaceable>level</replaceable>]</term>
<term><option>--compress=[[{<replaceable class="parameter">client|server</replaceable>-}]<replaceable class="parameter">method</replaceable></option>[:<replaceable>level</replaceable>]</term>
<listitem>
<para>
Enables compression of tar file output, and specifies the
compression level (0 through 9, 0 being no compression and 9 being best
compression). Compression is only available when using the tar
format, and the suffix <filename>.gz</filename> will
automatically be added to all tar filenames.
Requests compression of the backup. If <literal>client</literal> or
<literal>server</literal> is included, it specifies where the
compression is to be performed. Compressing on the server will reduce
transfer bandwidth but will increase server CPU consumption. The
default is <literal>client</literal> except when
<literal>--target</literal> is used. In that case, the backup is not
being sent to the client, so only server compression is sensible.
When <literal>-Xstream</literal>, which is the default, is used,
server-side compression will not be applied to the WAL. To compress
the WAL, use client-side compression, or
specify <literal>-Xfetch</literal>.
</para>
<para>
The compression method can be set to either <literal>gzip</literal>
for compression with <application>gzip</application>, or
<literal>none</literal> for no compression. A compression level
can be optionally specified, by appending the level number after a
colon (<literal>:</literal>).
colon (<literal>:</literal>). If no level is specified, the default
compression level will be used. If only a level is specified without
mentioning an algorithm, <literal>gzip</literal> compression will
be used if the level is greater than 0, and no compression will be
used if the level is 0.
</para>
<para>
When the tar format is used, the suffix <filename>.gz</filename> will
automatically be added to all tar filenames. Compression is not
available in plain format.
</para>
</listitem>
</varlistentry>