select query taking long time to execute during background execution.

Hi all,

We are facing an issue while running a background job select query is used to process entry from one ztable.

but it takes longer than usual, due to which this job goes in long running.

Any possible reasons of table being locked or any other reasons for query to process for such a long duration?

SELECT zcolumns
FROM ztables UP TO 1 ROWS
INTO lwa_table
WHERE zfield1 EQ primary_key_1
AND zfield2 EQ primary_key_2
ORDER BY key_field.