| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Neil Conway <neilc(at)samurai(dot)com>, Zoltan Boszormenyi <zb(at)cybertec(dot)at>, List pgsql-patches <pgsql-patches(at)postgresql(dot)org>, Decibel! <decibel(at)decibel(dot)org>, Steve Crawford <scrawford(at)pinpointresearch(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [HACKERS] TRUNCATE TABLE with IDENTITY |
| Date: | 2008-06-08 16:26:06 |
| Message-ID: | 4909.1212942366@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-patches |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Tom Lane wrote:
>> 2. I had first dismissed Neil's idea of transactional sequence updates
>> as impossible, but on second look it could be done. Suppose RESTART
>> IDENTITY does this for each sequence;
>>
>> * obtain AccessExclusiveLock;
>> * assign a new relfilenode;
>> * insert a sequence row with all parameters copied except
>> last_value copies start_value;
>> * hold AccessExclusiveLock till commit.
> Hmm, this kills the idea of moving sequence data to a single
> non-transactional catalog :-(
Well, there are a number of holes in our ideas of how to do that anyway.
But offhand I don't see why we couldn't distinguish regular heap_update
from update_in_place on single rows within a catalog.
regards, tom lane
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