Ivan,
The data that is loaded into Sedna comes from the same source. The only
difference is that one is chunked up into individual XML files and the
other is a single large XML document containing the same info.
So when I create two variables containing the same content but from
different sources (one a collection and the other a single XML doc) and
then do a union on them I should only get the unique nodes as per your
example below. But that is not what is happening. It is returning all 22
album nodes (11 album nodes from each). When I output each to their own
file and do a comparison using Oxygen's XML diff tool, according to that
tool they are identical. Am I missing something here on how union is
supposed to work?
Also the second issue is I was just returning @ids to see that the order
was correct. They are both sorted the same and when I view the XML (from
the output files above) they are identical and both sorted exactly the
same, I can't stress that enough. The first variable (l_Content1) the
IDs are output in the order they were sorted and appear in the XML file
but the second variable's (l_Content2) the IDs do not appear in the
sorted order but the output XML file has them in the sorted order. I
find this confusing as to why this is happening. Both variables contain
the exact same data.
The XML that I gave must be inserted into Sedna as is for the first
variable but must be chunked into individual XML files (with album as
root) and then inserted into a collection. I don't know whether you have
done that or not and hence the results I'm seeing are not being duplicated.
I hope that helps in clarifying what I am seeing.
Marijan (Mario) Madunic
On 7/31/2012 9:43 AM, Ivan Shcheklein wrote:
Hi Marijan,
I'm having an issue with union that I can't seem to see what's
wrong. It
always returns the entire result of both sets of XML but they are
basically exactly the same.
See http://www.w3.org/TR/xquery/#combining_seq .
"All these operators [/including union/] eliminate duplicate nodes
from their result sequences based on node identity"
It means, that the following query returns two nodes:
let $a := <a id='1'/>
let $b := <b id='1'/>
return $a/@id union $b/@id
while:
let $a := <a id='1'/>
return $a/@id union $a/@id
returns one node.
Union operation in XQuery doesn't compare values of nodes (IDs in your
case). There is distinct-values function to remove duplicates by value:
let $l_UnionContent := distinct-values(($l_Content1, $l_Content2))
...
Another issue I found was that $l_Content2 even though sorted (when I
view the result XML both $l_Content1 and $l_Content2 are ordered
exactly
the same) is out of order when I want to view just the IDs.
I've failed to reproduce this issue:
[shcheklein@dhcp-218-16-wifi ~/sedna-3.5.161/bin]$ ./se_term x
Welcome to term, the SEDNA Interactive Terminal. Type \? for help.
x> create collection "c_AlbumsIndividual"&
UPDATE is executed successfully
x> load "./test.xml" "albums" "c_AlbumsIndividual"&
Bulk
load succeeded
x> CREATE INDEX "AlbumsByArtistCollection" ON
collection("c_AlbumsIndividual")/albums/album BY
artists/artist/@artistID AS xs:string&
UPDATE is executed successfully
x> declare variable $p_Index2 as xs:string :=
"AlbumsByArtistCollection";
declare variable $p_Value2 as xs:string :=
"artist_709";
let $l_Content2 := for $l_ContentTemp2 in
index-scan($p_Index2,
$p_Value2, "EQ") order by
number(substring-after($l_ContentTemp2/@id,
'album_')) return $l_ContentTemp2
return
$l_Content2/@id&
id="album_505"
id="album_506"
id="album_507"
id="album_508"
id="album_509"
id="album_982"
id="album_2476"
id="album_2591"
id="album_2596"
id="album_2599"
id="album_2874"
x> doc('$version')&
<sedna version="3.5" build="161"/>
Ivan Shcheklein,
Sedna Team
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