Hi again, Soumadri!
At 2009-12-05 18:49 +0530, Chowdhury, Soumadri wrote:
I have written two consecutive FLOWR expressions like the following,
let $a1 := "" return (xdmp:document-insert("/demo010",<a>data</a>)),
let $a2 := "" return (fn:doc("/demo010"))
The problem is the 2nd line returns an empty sequence, instead of
the content of the uri "/demo010"
How to resolve this problem? Any idea?
I learned the answer recently: it has to do with database
transactions. Certain database transactions are not committed to the
database until the query is complete.
As a test I formally declared the module to be using the Mark Logic
version of the language:
xquery version "1.0-ml";
let $a1 := "" return (xdmp:document-insert("/demo010",<a>data</a>)),
let $a2 := "" return (fn:doc("/demo010"))
... which didn't work as yours didn't work and then changed it to:
xquery version "1.0-ml";
let $a1 := "" return (xdmp:document-insert("/demo010",<a>data</a>));
let $a2 := "" return (fn:doc("/demo010"))
... which worked fine. Note the change of the comma to a semi-colon
at the end of the first assignment.
This is using the Mark Logic extension to XQuery of ending a query
with a semi-colon which allows one to put multiple queries in a
single document. The first query ends at the semi-colon and the
database does its business of committing all of the changes. The
second query is then acting on a complete database with your more
recent addition and finds it.
Since we are now dealing with complete queries instead of portions of
a FLWOR expression, your test can be rewritten as follows:
xquery version "1.0-ml";
xdmp:document-insert("/demo010",<a>data</a>);
fn:doc("/demo010")
I haven't yet learned *when* queries need to be flushed/committed to
the database, and I hope someone on the list can give general
guidelines ... but this is how I recently resolved a related Mark
Logic database issue.
Perhaps is there a formal request one can make in a query to commit
any uncommitted transactions?
I hope this helps.
. . . . . . . . . . . . Ken
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