RMS Indexed File Performance Issue: Duplicate Key Chains


	RMS Indexed File Performance Issue: Duplicate Key Chains

JohnBFisher

8-6-2008 4:11 PM

322 views

tags:

openvms, vms, rms, sidr, duplicate key chains

JohnBFisher says:

Known as Secondary Index Data Record (SIDR) chains, RMS indexed files can increase system overhead without the developer or system manager being aware of this issue. In this VMS Technical Journal article, Hein van den Heuvel discusses this issue an methods to address the problem.

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<div style="margin: 12px 0px; font-family: arial; color: #333333; background: #ffffff; border: solid 4px #e5e5e5; width: 100%; clear: left;"><div class="CM_CTB_Content_Wrap" style="margin: 0px; padding: 0px;background-color: #ffffff;"><div style="border-bottom: solid 1px #dcdcdc; white-space: nowrap; margin-bottom: 8px; background-color: #eeeeee ;background-image: url(http://clipmarks.com/images/source-bg.gif); background-repeat: repeat-x; height: 24px; line-height: 24px; vertical-align: middle; padding-bottom: 4px; color: #666666; font-size: 10px;" ><a href="http://clipmarks.com/clip-to-blog/" title="see clips that are hot right now"><img src="http://content.clipmarks.com/blog_embed/d70b9ce2-16b6-4c83-ad81-cd91f3fcfae2/744B4E32-E79A-41FE-9E6C-958B872F71A2/" alt="" width="19" height="19" border="0" style="vertical-align: middle; margin: 0px 4px; display: inline; border: none; float:none;" /></a>clipped from <a title="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html" href="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html" style="font-size: 11px;">h71000.www7.hp.com</a></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><div align="center"><img src="http://content6.clipmarks.com/blog_cache/h71000.www7.hp.com/img/D408A548-AE6D-4853-A312-6598CF450F6D" alt="HP.com home" /></div></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><H1>HP OpenVMS Systems</H1></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><H2 class="themeheader">RMS Performance: Duplicate key chains</H2></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><P>Hein van den Heuvel
</P></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><H1>Overview</H1></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html"><P>Does
your application use RMS Indexed files?
Do you know what a SIDR is? Do you know what a duplicate key chain is?
You probably should, since SIDRs and duplicate key chains can cause thousands
of read I/Os as the result of a single record insert. With that, they can have
a tremendous impact not just on the application doing the insert, but also on
total system performance. Application managers, of course, notice
a slowdown over time, and all too often they solve that by throwing more
hardware at the problem. But what if you already have the biggest box on the
market? Modest file tuning and a convert can help avoid all those read I/Os and
restore performance. I have yet to investigate an RMS application that did not
have this duplicate key chain problem. Maybe this is because I get called in
only for bad cases, or because indeed so many applications have this problem,
at least to some degree.
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