-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Roché Compaan wrote: > On Sat, 2008-10-25 at 09:20 +0200, Hedley Roos wrote: >>> Have you measures the time needs for some "standard" ZCatalog queries >>> used with a Plone site with the communication overhead with memcached? >>> Generally spoken: I think the ZCatalog is in general fast. Queries using a >>> fulltext index are known to be more expensive or if you have to deal with >>> large resultsets or complex queries. >>> >> No I haven't. Roche Compaan has done extensive benchmarking using >> funkload testing plain catalog vs module level cache vs memcached, but >> the tests are more about page serving than catalog query time. I'll >> ask him to comment more on that. > > I actually did some profiling as well and catalog searches were just too > damn slow. The average execution time for searchResults was 100 > milliseconds and this is why I told Hedley we should do some caching at > query level in the first place. I experimented with this idea a couple > of years back but wasn't successful due to inexperience. I was trying to > cache brains which obviously leads to persistency bugs. This time around > it was obvious to me that we should cache the IISet result sets. > > I suspect specific indexes are just performing suboptimally and needs to > be improved. ExtendPathIndex in Plone seems to be one of them. > > The effect on performance is really awesome, now we just need to fine > tune the implementation.
Before (or while) we work on caching, can we try to improve the underlying indexes, and the way that applications use them? I'm pretty sure that there is a lot of room for improvement: - Plone uses too many indexes, and in particular, uses multiple text indexes. Having extra indexes around "just in case" is a sure lose a write time, and may even be expensive at query time (depending on the query). - Particular indexes have performance characteristics based on their designed purpose: for instance, the stock FieldIndex implementation assumes that the number of documents indexed will be >> the number of discrete indexable values. Using such an index in an application domain with a very large set of indexable values probably loses, and in ways which don't show up in early / small-scale testing. - I'm pretty sure that we haven't yet found the best data structure for "hierarchy indexes" (e.g., the Plone EPI index, or the stock Zope2 PathIndex, etc.). Something like a 'trie' might be optimal for pure prefix searching of hierarchies. - I am confident that the TopicIndex is underutiliized: it does *all* the work for a given query at write time, and can thus be blindingly fast at query time. - Other special-purpose indexes (e.g., a "recent items" index) would be worth a look, especially for applications with large volumes of content. Tres. - -- =================================================================== Tres Seaver +1 540-429-0999 [EMAIL PROTECTED] Palladion Software "Excellence by Design" http://palladion.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFJBLHb+gerLs4ltQ4RAp59AJwNlfjI0tBv4PdMiDdH4TLKSm5YfwCgu8xB F3u1G0onXKKZ4s7MbLj9B2w= =r0oE -----END PGP SIGNATURE----- _______________________________________________ Zope-Dev maillist - Zope-Dev@zope.org http://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope )