04-20-2017 09:08 PM
using impala 2.7(8) with cdh5.10.1 here.
I am trying a simple query :
`select distinct(date_col_partition) from table_1`
and it is taking 20 sec.
But When I do a set DISABLE_CODEGEN=true;
It take only less than a second.
here is the profle gist: https://gist.github.com/anonymous/1a5faa3a10d4495f7b8abc3c964457db
Any idea of what is going wrong?
04-20-2017 09:45 PM
As an experiment, it would be interesting to try the query with the same data using a different data format, e.g., text. You can do a quick CREATE TABLE test as SELECT * FROM <original_table> and the retry the query.
04-20-2017 11:14 PM
Thanks for investigating. We've confirmed internally that the issue is related to Avro with many columns. 900 is somewhat wide.
Thanks for reporting! We'll continue to look into this issue.