Hello, I found that a number of similar queries have quite different performance: xquery doc('mcev_temp_5/20140130_11_55_40.xml')//column[@name='KLV_m1_rdr']/v takes only 0.68ms, which is great. But xquery doc('mcev_temp_5/20140130_11_55_40.xml')//column[@name='KLV_m1_rdr']/v[1] takes 1479.81ms. If I change this to the equivalent (for my data) xquery (doc('mcev_temp_5/20140130_11_55_40.xml')//column[@name='KLV_m1_rdr'])/v[1] it runs fast again (0.53ms) Checking the query execution plan I found that only query 1 and 3 utilize the attribute index. I find this rather surprising, and I would like to ask if there is some general reason/rule why the second can not use the index, so I can avoid such 'bad' queries in the future. Thanks! (I am using BaseX 7.7.2 on Windows XP.) Regards, Robert