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Roy,</div>
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I had to look up "abstemious" ...</div>
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<p style="margin-top: 0px; margin-bottom: 0px;">Michael Leo</p>
<p style="margin-top: 0px; margin-bottom: 0px;">Kettle River Consulting Inc</p>
<p style="margin-top: 0px; margin-bottom: 0px;">612-859-2108</p>
<p style="margin-top: 0px; margin-bottom: 0px;">mleo@kettleriverconsulting.com</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size: 11pt;"><b>From:</b> info-ingres-bounces@lists.planetingres.org <info-ingres-bounces@lists.planetingres.org> on behalf of Roy Hann <specially@processed.almost.meat><br>
<b>Sent:</b> Thursday, September 9, 2021 9:44 AM<br>
<b>To:</b> info-ingres@lists.planetingres.org <info-ingres@lists.planetingres.org><br>
<b>Subject:</b> Re: [Info-ingres] 4k Cache</font>
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<div class="PlainText">Steve wrote:<br>
<br>
> God willing, as mentioned above, I plan to increase the page size of<br>
> all user tables and indexes to 8k and 4k, respectively. Currently both<br>
> are 2k. This was a recommendation by Actian.<br>
> <br>
> A small portion of the tables are already 8k; that being the default<br>
> page size.<br>
> <br>
> Upon making these changes, I was thinking of reducing the 2k buffer cache<br>
> by 75%, as the only 2k tables at that point would be the system catalogs<br>
> (I think they˘re 2k) and possibly the odd users˘ own private tables. I<br>
> figured the memory saved could be reallocated to the 8k cache. Is that<br>
> a reasonable idea?<br>
<br>
It's not unreasonable, but generally I think Ingres is abstemious<br>
to a fault with DMF memory. Freeing up what is probably only a very<br>
small amount of memory won't make much difference.<br>
<br>
I am not the world's biggest fan of 4k pages. Owing to the larger<br>
per-row overhead of "large" pages you might find you waste less disk<br>
space if you just use 8k pages for everything.<br>
<br>
You don't mention what you are expecting to get from larger page sizes.<br>
They do enable ALTER TABLE which is handy, but if you are<br>
using locking (and you will be) rather than MVCC you might find page<br>
sizes bigger than 2k aggravate any lock-contention you may have.<br>
<br>
Please let us know how you get on. <br>
<br>
Roy<br>
<br>
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