[Zope] ZCatalog queries performance

Sebastian Tänzer st at taenzer.me
Tue May 19 12:57:12 CEST 2015

Thanks, this answered all of my questions :-)

Best, Sebastian 

> Am 19.05.2015 um 12:50 schrieb Tres Seaver <tseaver at palladion.com>:
> Hash: SHA1
>> On 05/19/2015 04:54 AM, Sebastian Tänzer wrote:
>> Let’s say I want to display an accordion with all events of a month 
>> displaying quite a lot of data about the event (30-50 events on one 
>> page, collapsible jQuery accordion). At the moment I get the results
>> and put the objects into the result set via unrestrictedTraverse
>> using getPath(). Would it be better to only get the path and get the
>> object in the template? Does this make any difference performance
>> wise?
> Nope.  Doing it in trusted code (an actual method, and ExternalMethod, or
> a view) would be faster than either a script or a template.  Measure it
> to decide whether to switch, however.
>> Which data of the event objects would I keep as ZCatalog meta columns 
>> and which not? Documentation is not really helpful on this.
> It is super application-dependent.  The costs for maintaining "extra"
> columns of metaata are relatively small (bloating the Record object, and
> therefore its pickle, mostly).
>> The tricky part is that events are linked with different locations 
>> (event location, selling points) that are not children of the event 
>> object but objects in a different folder. The event object itself
>> only keeps the links to these location objects and I get them when
>> iterating over the result set in the template.
> If you can define a URL-addressible method of the event which returns or
> redirects to those objects, you can get away with hard-wiring that in
> your template, using 'brain.getPath()' as a prefix.
>> Any advice what would be the best way for this performance-wise? Is
>> it okay to get the object itself via traversal? Is there a faster way
>> to get the object data?
> Fetching the object is fast if it is already in the ZODB cache, but slow
> if not, nd may cause other, more "popular" / important objects to be
> evicted.  Where possible, design for catalog queries which don't need to
> fetch the object.
> Tres.
> - -- 
> ===================================================================
> Tres Seaver          +1 540-429-0999          tseaver at palladion.com
> Palladion Software   "Excellence by Design"    http://palladion.com
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