| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Sergey Konoplev <gray(dot)ru(at)gmail(dot)com> |
| Cc: | Melvin Davidson <melvin6925(at)gmail(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Harald Fuchs <hari(dot)fuchs(at)gmail(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Converting char to varchar automatically |
| Date: | 2014-10-07 18:02:51 |
| Message-ID: | 28075.1412704971@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Sergey Konoplev <gray(dot)ru(at)gmail(dot)com> writes:
> On Tue, Oct 7, 2014 at 10:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Sergey Konoplev <gray(dot)ru(at)gmail(dot)com> writes:
>>> BTW, where can I find a list of type1->type2 pairs that doesn't
>>> require full table lock for conversion?
>> There aren't any. Sometimes you can skip a table rewrite, but that
>> doesn't mean that a lesser lock is possible.
> Oh, sorry, it was a typo, I meant "that doesn't require a full table rewrite".
Roughly speaking it's the pairs that have a binary (WITHOUT FUNCTION)
coercion according to pg_cast, although we have special logic for a few
cases such as varchar(M) -> varchar(N).
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | israel | 2014-10-07 19:06:07 | Re: Processor usage/tuning question |
| Previous Message | Sergey Konoplev | 2014-10-07 17:19:15 | Re: Converting char to varchar automatically |