| From: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Raúl Marín Rodríguez <rmrodriguez(at)carto(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] pow support for pgbench |
| Date: | 2017-12-01 22:23:37 |
| Message-ID: | alpine.DEB.2.20.1712012311470.5511@lancre |
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| Lists: | pgsql-hackers |
Hello Robert,
> The fact that the return type is not consistently of one type bothers
> me. I'm not sure pgbench's expression language is a good place to
> runtime polymorphism -- SQL doesn't work that way.
Sure.
Pg has a NUMERIC adaptative precision version, which is cheating, because
it can return kind of an "int" or a "float", depending on whether there
are digits after the decimal point or not.
Pgbench does not have support for NUMERIC, just INT & DOUBLE, so the
current version is an approximation of that.
Now it is always possible to just do DOUBLE version, but this won't match
SQL behavior either.
> + /*
> + * pow() for integer values with exp >= 0. Matches SQL pow() behaviour
> + */
>
> What's the name of the backend function whose behavior this matches?
POW(numeric,numeric) -> numeric, which matches "numeric_power".
--
Fabien.
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