Re: truncate in transaction blocks read access

On Mon, 2009-11-30 at 10:50 -0800, Craig James wrote:
> I have a million-row table (two text columns of ~25 characters each plus two integers, one of which is PK) that is replaced every week. Since I'm doing it on a live system, it's run inside a transaction. This is the only time the table is modified; all other access is read-only.
>
> I wanted to use "truncate table" for efficiency, to avoid vacuum and index bloat, etc. But when I do "truncate" inside a transaction, all clients are blocked from read until the entire transaction is complete. If I switch to "delete from ...", it's slower, but other clients can continue to use the old data until the transaction commits.
>
> The only work-around I've thought of is to create a brand new table, populate it and index it, then start a transaction that drops the old table and renames the new one.
>
> Any thoughts?

Use partitioning so you can roll off data.

http://www.postgresql.org/docs/8.3/interactive/ddl-partitioning.html

Joshua D. Drake

>
> Thanks,
> Craig
>
>

--
PostgreSQL.org Major Contributor
Command Prompt, Inc: http://www.commandprompt.com/ - 503.667.4564
Consulting, Training, Support, Custom Development, Engineering
If the world pushes look it in the eye and GRR. Then push back harder. - Salamander