[IMPALA-1607] Altering a column's type causes column stats to stop sticking for that column

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Not A Bug
• Affects Version/s: Impala 2.1
• Fix Version/s: Impala 2.2
• Labels: compute-stats ramp-up
• Assignee: Henry Robinson
• Reporter: Henry Robinson
• Created: 12/Dec/14 00:12
• Updated: 04/Jan/17 23:58
• Resolved: 05/Mar/15 01:01

Description

Changing a column's type by ALTER TABLE CHANGE ... leads to column stats for that column failing to persist.

Therefore every COMPUTE INCREMENTAL STATS after that turn into a full scan, because Impala believes the column doesn't have stats and needs to rescan the table, not to mention the fact that the statistics on that column are permanently wrong.