Hi ML team,
We have been using xdml:query-trace to analyse a slow running query and have
eliminated all of our "unsearchable"s except one, which we don't fully
understand.
In the ErrorLog output we see "Step 4 is unsearchable: text()" for any
property we retrieve with "text()" as follows:
Eg.
for $documentUri in $uris
let $documentProperties := xdmp:document-properties($documentUri)
let $modifiedBy :=
$documentProperties/prop:properties/prop:modifiedBy/text()
I think we're just realising that we shouldn't be getting the text node with
text() anyway but use string() but in any case I'm curious to know why that
text node is unsearchable. Just for my understanding.
When using text() like this does ML go back to disk as suggested in the "Tuning
Queries with query-meters and query-trace (Query Performance and Tuning Guide)"
which says "Expressions that are unsearchable cannot use the indexes, and must
fetch the data from disks"? I am new to marklogic and in a little at the deep
end with this analysis so excuse any false assumption, but I would have assumed
that the documentProperties are now in memory and so calling text() on that in
memory object should read from memory (if not the index) and not go back to
disk. Is that true? But in any case why is it considered unsearchable at all?
Would be grateful for an explanation and to set me straight on any
misunderstandings.
Many thanks,
Rachel
PS. And actually we've just determined that string() is unsearchable as well
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