| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Noah Misch <noah(at)leadboat(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: 9.3: load path to mitigate load penalty for checksums |
| Date: | 2012-06-12 21:55:30 |
| Message-ID: | 1339538130.12295.43.camel@sussancws0025 |
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| Lists: | pgsql-hackers |
On Tue, 2012-06-12 at 13:10 -0400, Robert Haas wrote:
> I don't think it's going to solve the problem in general, but TBH I
> don't think Jeff's proposal is, either. I mean, ignoring
> xmin-committed, xmax-committed, and all-visible bits is going to come
> with a pretty steep performance penalty all of its own.
I think we'd certainly have to discourage users from launching lots of
full table scans during a data load. We could go so far as blocking
reads, as I said in my other response, and still (mostly) meet my
primary goals.
But allowing reads without hint bits might be useful for highly
selective index access, which is a substantial use case for the kind of
large tables we'd be bulk-loading.
Regards,
Jeff Davis
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