| From: | Francisco Olarte <folarte(at)peoplecall(dot)com> |
|---|---|
| To: | Melvin Davidson <melvin6925(at)gmail(dot)com> |
| Cc: | Jacek Kołodziej <kolodziejj(at)gmail(dot)com>, pgsql-general(at)lists(dot)postgresql(dot)org |
| Subject: | Re: READ COMMITTED vs. index-only scans |
| Date: | 2018-01-17 15:21:53 |
| Message-ID: | CA+bJJbz5Sj5nBAxH4My4P9ZXg+3Y5mmn8H5C8FOkaHzqPTh4pg@mail.gmail.com |
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| Lists: | pgsql-general |
On Wed, Jan 17, 2018 at 3:30 PM, Melvin Davidson <melvin6925(at)gmail(dot)com> wrote:
....
> Just a suggestion. The first query is not really needed.
> You can simply do:
> second query (B):
>
> SELECT id
> , ...
> FROM events
> WHERE id > MIN(ID)
> AND id <= MAX(ID)
> AND ...
>
> See https://www.postgresql.org/docs/9.6/static/functions-aggregate.html
> MAX and MIN functions
Are you sure? ( http://sqlfiddle.com/#!17/7805a/3 )
In fact your link, in the first paragraph, points to
https://www.postgresql.org/docs/9.6/static/tutorial-agg.html which,
near the end ( 2nd paragraph from the end, I think its called next to
last in English, but not sure if penultimate is the correct word, like
in Spanish ), states:
"Thus, the WHERE clause must not contain aggregate functions; it makes
no sense to try to use an aggregate to determine which rows will be
inputs to the aggregates."
Francisco Olarte.
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