| From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Postgres insert performance and storage requirement compared to Oracle |
| Date: | 2010-10-26 23:16:53 |
| Message-ID: | AANLkTi=-fK6ODDNJPntq3OeUJQzKtHbsmkdDM851waOG@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Tue, Oct 26, 2010 at 6:50 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Oct 26, 2010 at 5:54 PM, Mladen Gogala
> <mladen(dot)gogala(at)vmsinfo(dot)com> wrote:
>> The table is created with "on commit obliterate rows" option which means
>> that there is no need to do "truncate". The "truncate" command is a heavy
>> artillery. Truncating a temporary table is like shooting ducks in a duck
>> pond, with a howitzer.
>
> This is just not true. ON COMMIT DELETE ROWS simply arranges for a
> TRUNCATE to happen immediately before each commit. See
> PreCommit_on_commit_actions() in tablecmds.c.
quite so. If you are doing anything performance sensitive with 'on
commit drop', you are better off organizing a cache around
txid_current() (now(), pid for older pg versions). Skips the writes
to the system catalogs and truncate.
merlin
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