Unless I'm missing something, you shouldn't need the eval. Constructors for cts:query are already fully composable. See the if-then-else expression that I outlined below.
-- Mike On 16 Apr 2012, at 09:04 , Gary Larsen wrote: > I'm worried about scalability in a large database and other xquery > conversions have really increased performance. > > What I'm trying now is to build the cts query string dynamically where I can > use 'if then else' to add the necessary cts syntax, and then do xdmp:eval() > on the string in cts:search. > > A simple test seemed to work ok. Does that make sense? > > Gary > > -----Original Message----- > From: general-boun...@developer.marklogic.com > [mailto:general-boun...@developer.marklogic.com] On Behalf Of Michael > Blakeley > Sent: Monday, April 16, 2012 11:53 AM > To: MarkLogic Developer Discussion > Subject: Re: [MarkLogic Dev General] simple cts constructor for variable > check > > The quick answer is something like: > > if ($oc) then () else cts:element-value-query(xs:QName(nv:objectClass), > $oc) > > When $oc is empty, there is no need to include that query term at all. So it > can be empty too. > > However, the long answer is that converting an XPath expression to cts:query > won't necessarily improve performance. If you don't need composability or > relevance ranking, you might as well stick with XPath. > > But trying to express an XPath as a cts:query can be a useful exercise, > because anything that won't map easily is likely to be expensive and > anything that can be expressed in cts:query is likely to be efficient. It is > tricky to say exactly what is going on without profiler output, but I > imagine that the expensive bits of your XPath are probably the nested steps. > For example: > > $oc = nv:lookupInfo/nv:objectClass > > nvdiff:diff/nv:content/nv:crnData8[nv:policies or nv:members] > > Wherever possible you want to rearrange the XPath steps so that they are > searchable and flat. Here's a slightly more efficient version: > > xdmp:directory("/db/netvisn/audit_history/", "infinity")/ > nv:auditHistory[not($oc) or $oc = nv:lookupInfo/nv:objectClass]/ > nv:audit[ > $effect ne "spec" or nv:sync/nv:archived] > [$effect ne "security" or > nvdiff:diff/nv:content/nv:crnData8/(nv:policies | nv:members)] > > -- Mike > > On 16 Apr 2012, at 08:21 , Gary Larsen wrote: > >> Hi >> >> I'm trying to convert a query to use cts for performance. Is there a cts > constructor that I can use the check a variable? >> >> Here's a portion of the query: >> >> xdmp:directory('/db/netvisn/audit_history/','infinity') >> /nv:auditHistory >> [fn:not(fn:exists($oc)) or $oc = > nv:lookupInfo/nv:objectClass] >> /nv:audit >> [$effect ne 'spec' or nv:sync/nv:archived] >> [$effect ne 'security' > ornvdiff:diff/nv:content/nv:crnData8[nv:policies or nv:members]] >> >> >> For example I would like to turn this portion into a cts:or-query > >> >> $effect ne 'spec' or nv:sync/nv:archived >> >> For second part I can use a cts:element-value-query(). I need something > for the first part. >> >> Or maybe I'm looking at this all wrong. Thanks for any suggestions. >> >> Gary >> >> _______________________________________________ >> General mailing list >> General@developer.marklogic.com >> http://developer.marklogic.com/mailman/listinfo/general > > _______________________________________________ > General mailing list > General@developer.marklogic.com > http://developer.marklogic.com/mailman/listinfo/general > > _______________________________________________ > General mailing list > General@developer.marklogic.com > http://developer.marklogic.com/mailman/listinfo/general > _______________________________________________ General mailing list General@developer.marklogic.com http://developer.marklogic.com/mailman/listinfo/general
