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List:       postgresql-general
Subject:    Parallel Aware
From:       Marwan Almaymoni <marwan.mmm () gmail ! com>
Date:       2018-02-26 19:45:25
Message-ID: CAE8pKtm54a1Maz0ws0iKxgJC0wtTdxUEA49Rk8kfn+TX3Vmtxw () mail ! gmail ! com
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​Hi,

I'm trying to run my query in parallel mode. I have setup my tables with "
WITH(parallel_workers=2)" storage parameter and I've created indexes for
needed attributes.
I have also set:
max_worker_processes = 100
max_parallel_workers_per_gather = 2
max_parallel_workers = 100

However, when I uses EXPLAIN to check the query plan​, *all of the nodes
are set to "Parallel Aware"=false*. *Am I missing something?*

Here is my tables and indexes:
CREATE TABLE t1(id int PRIMARY KEY, name varchar(200))
WITH(parallel_workers=2);
CREATE TABLE t2(id int PRIMARY KEY, fid int, value varchar(200))
WITH(parallel_workers=2);
CREATE INDEX ind_t1_id ON t1 USING HASH (id);
CREATE INDEX ind_t2_fid ON t2 USING HASH (fid);

Here's the query I tested with EXPLAIN:
SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.fid WHERE t1.id > 100;

[Attachment #3 (text/html)]

<div dir="ltr"><div style="font-size:small;color:rgb(0,0,0);display:inline" \
class="gmail_default">​Hi,<br><br></div><div \
style="font-size:small;color:rgb(0,0,0);display:inline" class="gmail_default">I&#39;m \
trying to run my query in parallel mode. I have setup my tables with &quot; \
WITH(parallel_workers=2)&quot; storage parameter and I&#39;ve created indexes for \
needed attributes.<br></div><div \
style="font-size:small;color:rgb(0,0,0);display:inline" class="gmail_default">I have \
also set:<br>max_worker_processes = 100<br>max_parallel_workers_per_gather = \
2<br>max_parallel_workers = 100<br><br></div><div \
style="font-size:small;color:rgb(0,0,0);display:inline" \
class="gmail_default">However, when I uses EXPLAIN to check the query plan​, <b>all \
of the nodes are set to &quot;Parallel Aware&quot;=false</b>. <b>Am I missing \
something?</b><br><br></div><div \
style="font-size:small;color:rgb(0,0,0);display:inline" class="gmail_default">Here is \
my tables and indexes:<br>CREATE TABLE t1(id int PRIMARY KEY, name varchar(200)) \
WITH(parallel_workers=2);<br>CREATE TABLE t2(id int PRIMARY KEY, fid int, value \
varchar(200)) WITH(parallel_workers=2);<br>CREATE INDEX ind_t1_id ON t1 USING HASH \
(id);<br>CREATE INDEX ind_t2_fid ON t2 USING HASH (fid);<br><br></div><div \
style="font-size:small;color:rgb(0,0,0);display:inline" \
class="gmail_default">Here&#39;s the query I tested with EXPLAIN:<br>SELECT * FROM t1 \
INNER JOIN t2 ON <a href="http://t1.id">t1.id</a> = t2.fid WHERE <a \
href="http://t1.id">t1.id</a> &gt; 100;<br><br></div></div>



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