On Thu, 9 Jan 2020 at 17:31, Sergei Kornilov <sk@zsrv.org> wrote:
>
> Hello
>
> I noticed that parallel vacuum uses min_parallel_index_scan_size GUC to skip small indexes but this is not mentioned
indocumentation for both vacuum command and GUC itself.
>
> + /* Determine the number of parallel workers to launch */
> + if (lps->lvshared->for_cleanup)
> + {
> + if (lps->lvshared->first_time)
> + nworkers = lps->nindexes_parallel_cleanup +
> + lps->nindexes_parallel_condcleanup - 1;
> + else
> + nworkers = lps->nindexes_parallel_cleanup - 1;
> +
> + }
> + else
> + nworkers = lps->nindexes_parallel_bulkdel - 1;
v43-0001-Introduce-IndexAM-fields-for-parallel-vacuum and
v43-0001-Introduce-IndexAM-fields-for-parallel-vacuum patches look
fine to me.
Below are some review comments for v43-0002 patch.
1.
+ <term><replaceable class="parameter">integer</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a positive integer value passed to the selected option.
+ The <replaceable class="parameter">integer</replaceable> value can
+ also be omitted, in which case the value is decided by the command
+ based on the option used.
+ </para>
+ </listitem
I think, now we are supporting zero also as a degree, so it should be
changed from "positive integer" to "positive integer(including zero)"
2.
+ * with parallel worker processes. Individual indexes are processed by one
+ * vacuum process. At the beginning of a lazy vacuum (at lazy_scan_heap) we
I think, above sentence should be like "Each individual index is
processed by one vacuum process." or one worker
3.
+ * Lazy vacuum supports parallel execution with parallel worker processes. In
+ * a parallel lazy vacuum, we perform both index vacuuming and index cleanup
Here, "index vacuuming" should be changed to "index vacuum" or "index
cleanup" to "index cleaning"
Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com