| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>, 'Alvaro Herrera' <alvherre(at)2ndquadrant(dot)com> |
| Cc: | 'Michael Paquier' <michael(at)paquier(dot)xyz>, 'Robert Haas' <robertmhaas(at)gmail(dot)com>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, "Jamison, Kirk" <k(dot)jamison(at)jp(dot)fujitsu(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: reloption to prevent VACUUM from truncating empty pages at the end of relation |
| Date: | 2019-02-28 08:33:02 |
| Message-ID: | de64fda10b8df95d4fdc16c9c51beead41f88909.camel@cybertec.at |
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| Lists: | pgsql-hackers |
Tsunakawa, Takayuki wrote:
> Why do you think that it's better for VACUUM command to have the option? I think it's a
> table property whose value is determined based on the application workload, not per VACUUM
> execution. Rather, I think GUC is more useful to determine the behavior of the entire
> database and/or application.
I cannot speak for Alvaro, but I think that many people think that a global setting
is too dangerous (I personally don't think so).
And if we don't have a GUC, an option to VACUUM would be convenient for one-time
clean-up of a table where taking a truncation lock would be too disruptive.
> If we want to change a given execution of VACUUM, then we can ALTER TABLE SET, VACUUM,
> and ALTER TABLE SET back.
True. That ALTER TABLE would probably need a SHARE UPDATE EXCLUSIVE lock on the table,
and that's no worse than VACUUM itself.
Yours,
Laurenz Albe
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