database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-01 01:04:50 +03:00
Code

doc: pg_resetwal: Add comments how the multipliers are derived

Browse Source 
Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Discussion: https://www.postgresql.org/message-id/flat/0f3ab4a1-ae80-56e8-3426-6b4a02507687@eisentraut.org
This commit is contained in:
Peter Eisentraut 2023-11-06 08:17:54 +01:00
parent 93c85db3b5
commit 6ceec8a1fe
1 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
doc/src/sgml/ref/pg_resetwal.sgml
View File

@ -166,7 +166,8 @@ PostgreSQL documentation
<command>pg_resetwal</command> is unable to determine appropriate values <command>pg_resetwal</command> is unable to determine appropriate values
by reading <filename>pg_control</filename>. Safe values can be determined as by reading <filename>pg_control</filename>. Safe values can be determined as
described below. For values that take numeric arguments, hexadecimal described below. For values that take numeric arguments, hexadecimal
values can be specified by using the prefix <literal>0x</literal>. values can be specified by using the prefix <literal>0x</literal>. Note
that these instructions only apply with the standard block size of 8 kB.
</para> </para>
<variablelist> <variablelist>
@ -189,6 +190,7 @@ PostgreSQL documentation
greatest file name in the same directory. The file names are in greatest file name in the same directory. The file names are in
hexadecimal. hexadecimal.
</para> </para>
<!-- XXX: Should there be a multiplier, similar to the other options? -->
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -272,6 +274,7 @@ PostgreSQL documentation
names are in hexadecimal, so the easiest way to do this is to specify names are in hexadecimal, so the easiest way to do this is to specify
the option value in hexadecimal and append four zeroes. the option value in hexadecimal and append four zeroes.
</para> </para>
<!-- 65536 = SLRU_PAGES_PER_SEGMENT * BLCKSZ / sizeof(MultiXactOffset) -->
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -306,6 +309,7 @@ PostgreSQL documentation
The file names are in hexadecimal. There is no simple recipe such as The file names are in hexadecimal. There is no simple recipe such as
the ones for other options of appending zeroes. the ones for other options of appending zeroes.
</para> </para>
<!-- 52352 = SLRU_PAGES_PER_SEGMENT * floor(BLCKSZ/20) * 4; see multixact.c -->
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -354,6 +358,7 @@ PostgreSQL documentation
in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five
trailing zeroes provide the proper multiplier). trailing zeroes provide the proper multiplier).
</para> </para>
<!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -375,6 +380,7 @@ PostgreSQL documentation
in <filename>pg_xact</filename>, <literal>-x 0x1200000</literal> will work (five in <filename>pg_xact</filename>, <literal>-x 0x1200000</literal> will work (five
trailing zeroes provide the proper multiplier). trailing zeroes provide the proper multiplier).
</para> </para>
<!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>