Re: How should I specify work_mem/max_worker_processes if I want to do big queries now and then?

[James(王旭)]

Thanks Imre, this is a very important comment, 128 bits is much smaller than 
45*8+2=362.


Very glad to know that, thank you very much!


James
 
 
------------------ Original ------------------
From: &nbsp;"Imre Samu"<pella.s...@gmail.com&gt;;
Date: &nbsp;Thu, Nov 21, 2019 08:39 PM
To: &nbsp;"James(王旭)"<wan...@gu360.com&gt;; 
Cc: &nbsp;"pgsql-general"<pgsql-gene...@postgresql.org&gt;; 
Subject: &nbsp;Re: How should I specify work_mem/max_worker_processes if I want 
to do big queries now and then?

&nbsp;

&gt;&nbsp; uuid character varying(45) NOT NULL,


Just a comment.
IF this is a real UUID (&nbsp;RFC 4122, ISO/IEC 9834-8:2005 )&nbsp;;&nbsp;
THEN you can use the built in&nbsp; "UUID 
Type"&nbsp;&nbsp;https://www.postgresql.org/docs/11/datatype-uuid.html




"UUID would be the fastest because its 128 bits -&gt; 16 bytes and comparisons 
are done numerically."
https://stackoverflow.com/questions/32189129/performance-difference-between-uuid-char-and-varchar-in-postgresql-table

The smaller size can be important for your index size ! :&nbsp; 
&nbsp;"quotes_pkey PRIMARY KEY (symbol_id, uuid);"


Imre