The results of 'where' clause in FLWOR are different in memory and database.

[jesselet]

What is the problem

for $i in $data1//item, $j in $data2//item
where $i/name = $j/name
return $i/name

The results of 'where' clause in FLWOR are different in memory and database.

What did you expect

The results of 'where' clause in FLWOR are the same in memory and database.

Describe how to reproduce or add a test

xquery version "3.0";
let $col := "/db/apps/test"
let $data1 :=
<data>
    <item><name>1</name></item>
    <item><name>2</name></item>
</data>
let $data2 :=
<data>
    <item><name>2</name></item>
    <item><name>3</name></item>
</data>
let $test := function ($data1, $data2) {
    for $i in $data1//item, $j in $data2//item
    where $i/name = $j/name
    return $i/name
}
return (
    try {
        $test($data1, $data2)
    } catch * { "test1: " || $err:description },
    (:in eXist 2.2, 3.6.1, 4.6.1, 4.7.0: OK:)

    try {
        xmldb:create-collection("", $col),
        let $data1 := doc(xmldb:store($col, "data1.xml", $data1))
        let $data2 := doc(xmldb:store($col, "data2.xml", $data2))
        return $test($data1, $data2)
    } catch * { "test2: " || $err:description }
    (:in eXist 2.2: OK:)
    (:in eXist 3.6.1, 4.6.1, 4.7.0: EXCEPTION: variable '$j' is not set:)
)

Context information

• OS: Windows 7
• Java: jre1.8.0_202
• eXist-db: 2.2, 3.6.1, 4.6.1, 4.7.0

[duncdrum]

yup confirmed, and looks like a bug that has been there for a while, ouch.

tested on 5.0.0-RC8-SNAPSHOT via docker

[line-o]

I would also see this as a bug.
It can be worked around with:

    let $j := $data2//item
    return
    for $i in $data1//item
    where $i/name = $j/name
    return $i/name

[line-o]

The equivalent form described in the spec does also fail:

    for $i in $data1//item
    for $j in $data2//item
    where $i/name = $j/name
    return $i/name