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| author | Bruce Momjian <bruce@momjian.us> | 2021-07-26 22:38:14 -0400 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2021-07-26 22:38:14 -0400 |
| commit | 71121450e8f42b21665ee9c8f70b701f7a16c801 (patch) | |
| tree | 0d5c233c778c037f836013ea06a5b215285ca1a4 /doc/src | |
| parent | 4372f0685de164e769e895dbada18cad792192b2 (diff) | |
pg_resetxlog: add option to set oldest xid & use by pg_upgrade
Add pg_resetxlog -u option to set the oldest xid in pg_control.
Previously -x set this value be -2 billion less than the -x value.
However, this causes the server to immediately scan all relation's
relfrozenxid so it can advance pg_control's oldest xid to be inside the
autovacuum_freeze_max_age range, which is inefficient and might disrupt
diagnostic recovery. pg_upgrade will use this option to better create
the new cluster to match the old cluster.
Reported-by: Jason Harvey, Floris Van Nee
Discussion: https://postgr.es/m/20190615183759.GB239428@rfd.leadboat.com, 87da83168c644fd9aae38f546cc70295@opammb0562.comp.optiver.com
Author: Bertrand Drouvot
Backpatch-through: 9.6
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/pg_resetwal.sgml | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml index defaf170dc6..89ddca47e90 100644 --- a/doc/src/sgml/ref/pg_resetwal.sgml +++ b/doc/src/sgml/ref/pg_resetwal.sgml @@ -248,6 +248,25 @@ PostgreSQL documentation </varlistentry> <varlistentry> + <term><option>-u <replaceable class="parameter">xid</replaceable></option></term> + <listitem> + <para> + Manually set the oldest unfrozen transaction ID. + </para> + + <para> + A safe value can be determined by looking for the numerically smallest + file name in the directory <filename>pg_xact</filename> under the data directory + and then multiplying by 1048576 (0x100000). Note that the file names are in + hexadecimal. It is usually easiest to specify the option value in + hexadecimal too. For example, if <filename>0007</filename> is the smallest entry + in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five + trailing zeroes provide the proper multiplier). + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><option>-x</option> <replaceable class="parameter">xid</replaceable></term> <listitem> <para> |