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
replacedevery week.  Since I'm doing it on a live system, it's run inside a transaction.  This is the only time the
tableis 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"
insidea transaction, all clients are blocked from read until the entire transaction is complete.  If I switch to
"deletefrom ...", 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
transactionthat 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
>
>


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