On Fri, Apr 5, 2019 at 3:47 PM Kyotaro HORIGUCHI <horiguchi.kyot...@lab.ntt.co.jp> wrote: > > Thank you for the rebased version. > > At Fri, 5 Apr 2019 13:59:36 +0900, Masahiko Sawada <sawada.m...@gmail.com> > wrote in <cad21aoc_s0h0x-ddphvjeqmycnkyomjesxd6r_9bbc3zzeg...@mail.gmail.com> > > Thank you for the notice. Rebased. > > + <term><replaceable class="parameter">integer</replaceable></term> > + <listitem> > + <para> > + Specifies parallel degree for <literal>PARALLEL</literal> option. The > + value must be at least 1. If the parallel degree > + <replaceable class="parameter">integer</replaceable> is omitted, then > + <command>VACUUM</command> decides the number of workers based on > number of > + indexes on the relation which further limited by > + <xref linkend="guc-max-parallel-workers-maintenance"/>. > + </para> > + </listitem> > + </varlistentry> >
Thank you for reviewing the patch. > I'm quite confused to see this. I suppose the <para> should be a > description about <integer> parameters. Actually the existing > <boolean> entry is describing the boolean itself. > Indeed. How about the following description? PARALLEL Perform vacuum index and cleanup index phases of VACUUM in parallel using integer background workers (for the detail of each vacuum phases, please refer to Table 27.25). If the parallel degree integer is omitted, then VACUUM decides the number of workers based on number of indexes on the relation which further limited by max_parallel_maintenance_workers. Only one worker can be used per index. So parallel workers are launched only when there are at least 2 indexes in the table. Workers for vacuum are launched before starting each phases and exit at the end of the phase. These behaviors might change in a future release. This option can not use with FULL option. integer Specifies a positive integer value passed to the selected option. The integer value can also be omitted, in which case the default value of the selected option is used. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
