Hi,

We are testing Apache Impala and have noticed that using GROUP BY and LIKE together works very slowly -- separate queries work much faster. Here are two examples:

SELECT * FROM hive.default.pcopy1B where (lower("by") like '%part%' and lower("by") like '%and%' and lower("by") like '%the%') or (lower(title) like '%part%' and lower(title) like '%and%' and lower(title) like '%the%') or (lower(url) like '%part%' and lower(url) like '%and%' and lower(url) like '%the%') or (lower(text) like '%part%' and lower(text) like '%and%' and lower(text) like '%the%') limit 100;

1.37s 1.08s 1.35s

select "by", type, ranking, count(*) from pcopy where (lower("by") like '%part%' and lower("by") like '%and%' and lower("by") like '%the%') or (lower(title) like '%part%' and lower(title) like '%and%' and lower(title) like '%the%') or (lower(url) like '%part%' and lower(url) like '%and%' and lower(url) like '%the%') or (lower(text) like '%part%' and lower(text) like '%and%' and lower(text) like '%the%') group by "by", type, ranking order by 4 desc limit 10;
156.64s 155.63s

Could someone please explain why this issue occurs, and if there are any workarounds?

Thanks,

David