Re: UNION ALL

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Mark Pasterkamp <markpasterkamp1994(at)gmail(dot)com>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: UNION ALL
Date: 2019-08-15 18:49:31
Message-ID: 22055.1565894971@sss.pgh.pa.us
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Mark Pasterkamp <markpasterkamp1994(at)gmail(dot)com> writes:
> I was wondering if someone could help me understands what a union all
> actually does.

Generally speaking, it runs the first query and then the second query.
You'd really need to provide a lot more detail for anyone to say more
than that.

https://wiki.postgresql.org/wiki/Slow_Query_Questions

regards, tom lane

In response to

  • UNION ALL at 2019-08-15 18:37:06 from Mark Pasterkamp

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