| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Don Baccus <dhogaza(at)pacifier(dot)com> |
| Cc: | Mike Mascari <mascarim(at)yahoo(dot)com>, t-ishii(at)sra(dot)co(dot)jp, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] sort on huge table |
| Date: | 1999-11-02 03:37:57 |
| Message-ID: | 9950.941513877@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
> At 06:24 PM 11/1/99 -0800, Mike Mascari wrote:
>> I know this is a VERY long shot, but... what were the READ/WRITE ratios
>> between the old version and the new version? Perhaps the computation
>> of the checksum (sic) blocks under RAID5 caused the unexpected behavior.
Good try but no cigar --- we're dealing with a merge algorithm here,
and it's inherently the same amount of data in and out. You write
a block once, you read the same block once later on. But...
Don Baccus <dhogaza(at)pacifier(dot)com> writes:
> RAID 5, not the operating system, might be getting in the way...it
> would be interesting to test this on a Linux 2.2 kernel without
> the RAID 5 complication.
... I agree this'd be worth trying. There could be some subtle effect
somewhere in RAID5 that's tripping things up. It'd also be useful if
someone could try it on similar RAID hardware with a non-Linux kernel.
regards, tom lane
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