Hi Martin,

Thanks for the analysis. As you’ve already indicated, the combination of documents with and without namespaces triggered an optimization that should only take effect if all documents of a database have the same default namespace

The bug has been fixed; a new snapshot is online [1,2].

Best, Christian

[1] https://github.com/BaseXdb/basex/issues/1831 [2] http://files.basex.org/releases/latest/

On Mon, Mar 30, 2020 at 11:26 AM Martin Honnen martin.honnen@gmx.de wrote:

Am 29.03.2020 um 16:26 schrieb Martin Honnen:

...

Using BaseX 9.3.2, why does a query

collection('/test-db-1/bib')//Q{}libro

return 6 items while

collection('/test-db-1/bib')//libro

gives 0 items?

If I run

collection('/test-db-1/bib')//Q{}libro, collection('/test-db-1/bib')//libro

the info window shows

Compiling:

• rewrite fn:collection([uri]) to document-node() item:

collection("/test-db-1/bib") -> db:open-pre("test-db-1", 12000002)

• merge steps: descendant::element(libro)
• rewrite fn:collection([uri]) to document-node() item:

collection("/test-db-1/bib") -> db:open-pre("test-db-1", 12000002)

• remove step without results: element(libro)
• rewrite iter step to empty sequence: element(libro) -> ()
• rewrite cached path to empty sequence: db:open-pre("test-db-1",

12000002)/descendant-or-self::node()/() -> ()

• rewrite expression list to iter path: (db:open-pre("test-db-1",

12000002)/descendant::element(libro), ()) -> db:open-pre("test-db-1", 12000002)/descendant::element(libro) Optimized Query: db:open-pre("test-db-1", 12000002)/descendant::element(libro) Query: collection('/test-db-1/bib')//Q{}libro, collection('/test-db-1/bib')//libro Result:

• Hit(s): 6 Items
• Updated: 0 Items
• Printed: 1455 b
• Read Locking: test-db-1
• Write Locking: (none)

It seems the problems occurs if I have one document in the db that has elements in a namespace and one with elements in no namespace.

So if there is only one document with no namespaces then both collection('/test-db-3/ex2')//foo and collection('/test-db-3/ex2')//Q{}foo select the `foo` elements in no namespace but if there is a document using a namespace as well in the db then collection('/test-db-3/ex2')//foo does not select the `foo` elements in no namespace.

Are there any db/namespace related settings in BaseX that cause that behaviour?