<story><title>Parallelism in PostgreSQL</title><url>https://www.percona.com/blog/2019/07/30/parallelism-in-postgresql/</url></story><parent_chain></parent_chain><comment><author>macdice</author><text>The section on parallel joins is a bit out of date.  Shameless plug:  I&amp;#x27;ve written and spoken about this subject extensively, if you are looking for more information, with further links and pointers to other blogs and academic papers.&lt;p&gt;Parallelism in PostgreSQL in general:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;speakerdeck.com&amp;#x2F;macdice&amp;#x2F;parallelism-in-postgresql-11&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;speakerdeck.com&amp;#x2F;macdice&amp;#x2F;parallelism-in-postgresql-11&lt;/a&gt;&lt;p&gt;Deeper dives on hash joins:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;write-skew.blogspot.com&amp;#x2F;2018&amp;#x2F;01&amp;#x2F;parallel-hash-for-postgresql.html&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;write-skew.blogspot.com&amp;#x2F;2018&amp;#x2F;01&amp;#x2F;parallel-hash-for-po...&lt;/a&gt;
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;speakerdeck.com&amp;#x2F;macdice&amp;#x2F;hash-joins-past-present-and-future&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;speakerdeck.com&amp;#x2F;macdice&amp;#x2F;hash-joins-past-present-and-...&lt;/a&gt;</text></comment>
<story><title>Parallelism in PostgreSQL</title><url>https://www.percona.com/blog/2019/07/30/parallelism-in-postgresql/</url></story><parent_chain></parent_chain><comment><author>nymonym</author><text>I&amp;#x27;m not sure why the performance benefits hit a limit with 10 workers on a 64-core machine. It doesn&amp;#x27;t look like there should be too much communication complexity given largely disjoint workloads.&lt;p&gt;Are we hitting memory&amp;#x2F;IO bottlenecks?</text></comment>