Yes, I see now why my query returns much more hits than yours (including the first). As Liam already expressed, it’s not really a nested query what you are wanting to achieve.
Oe thing you can always try is to change the order of your for clauses and see what happens. Maybe you did that already? In all cases, no index will be applied at the moments with these kinds of query patterns. I might get back to you later or tomorrow once I have another idea what could be done. On Sat, Aug 22, 2020 at 6:42 PM Bill Osmond <b...@with.in> wrote: > > This is vexing - it seems as though the mechanism that provides the necessary > "filtering" is the very thing that slows the execution down so much. This > wouldn't have been obvious from the single example document I sent earlier, > but each document stands alone: all of the searching and reference linking > done for each TrackRelease in a NewReleaseMessage should only refer to other > nodes in that same NewReleaseMessage. > > In my query, I started out with "for $r in /ernm:NewReleaseMessage" and I > used $r on the right hand side of the subsequent for statements. It seems > like without that, the execution is quick, but all the results from every > document are getting matched to each other. With it, the results are correct, > but the execution time shoots way up. In case any of you still have any > patience for this question (and thanks again for everything so far!), I've > attached a small sample set of 6 documents. The desired number of results > from the query is 70 (which is the number of TrackReleases from all the > documents combined), and the query that I've adapted from Christian's > ddex2.xq which returns the right number of results is the following: > > declare namespace ernm = 'http://ddex.net/xml/ern/411'; > (: declare context item := db:open('ddex'); :) > > for $r in /ernm:NewReleaseMessage > > for $party in $r/PartyList/Party[ > PartyReference/text() = > $r/ReleaseList/TrackRelease/ReleaseLabelReference > ] > for $track_release in $r/ReleaseList/TrackRelease[ > ReleaseLabelReference/text() = > $r/PartyList/Party/PartyReference > ] > for $sound_recording in $r/ResourceList/SoundRecording[ > ResourceReference/text() = > $track_release/ReleaseResourceReference > ] > for $release in $r/ReleaseList/Release[ > > ResourceGroup/ResourceGroup/ResourceGroupContentItem/ReleaseResourceReference/text() > = > $track_release/ReleaseResourceReference > ] > return <identity> > <isrc>{ $track_release/ReleaseId/ISRC/text() }</isrc> > <artist>{ fn:string-join($sound_recording/DisplayArtistName, '/') }</artist> > <title>{ $sound_recording/DisplayTitleText/text() }</title> > <album>{ $release/DisplayTitleText/text() }</album> > <icpn>{ $release/ReleaseId/ICPN/text() }</icpn> > <sublabel>{ $party/PartyName/FullName/text() }</sublabel> > </identity>
