Add to this the fact that, given the usual page size of 4k, you're going to
do 25 physical disk reads to retrieve each item. I'd consider a redesign.
One place I tuned was doing 11 transactions per minute ("you mean, per
second?, I asked). It turns out that they were opening batches & leaving the
open for a month; the mv field holding the transaction remote key was
growing to 1-2Mb, and they weren't using raise() & lower() to maintain the
pointer, so every transaction had to start reading at the first byte...
Anyway, they put a forced limit of 100 transactions per batch into the code,
and then with some resizing went to 1400 tpm. Further resizing & hardware
upgrades & app tuning got 'em above 3k tpm.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Charles Stevenson
Sent: Thursday, April 23, 2009 1:12 PM
To: [email protected]
Subject: Re: [U2] Record Size Limit in UV
I've seen records at least an order of magnitude larger than that. Unix
& Windows. Megabytes. I want to say much larger than that, but I can't
verify that and when numbers get that big, my brain can't get around
them. ( e.g., $1,000,000,000,000: www.pagetutor.com/trillion/index.html )
I don't know of absolute limits, but performance takes a dive, of
course: lock contention, frequent updates, inappropriate indexes,
selections w/o indexing poorly sized files (they should be type 30, if
they must exist. The large records get isolated in their own
overflow). In general, U2 responds well to size abuse. Performance
degradation is fairly linear & responds well to throwing more hardware
at it. But at some point degradation curve becomes geometric.
I'm curious about whether your scenario matches the usual: i.e., an
application that has outgrown its original design, with a multi-valued
association in that gets updated frequently through the lfe of the record.
The original design intended a few mv entires, until the business
operation it represents gets closed. At some point someone decided to
use the association for some additional purpose. Some records remain
small, some grow, resulting in a very lumpy file. Many times it's the
users trying to respond quickly to a changing business need, w/o
waiting for IT to do the enhancement (they invent new status codes,
etc.). Sometimes it's programmers enamored by the siren call of mv nesting.
Adam Taylor wrote:
> Hey all,
>
> Can anyone tell me what (if any) the current record size limit is in UV
10.2?
> We've currently found ourselves in a situation where certain fields in a
data
> file will contain 100K+ characters and we would like to be proactive about
any
> potential problems if they exist.
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