[HIVE-10319] Hive CLI startup takes a long time with a large number of databases

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Fix Version/s: 1.3.0, 2.0.0
• Component/s: CLI
• Hadoop Flags: Reviewed
• Assignee: Nezih Yigitbasi
• Reporter: Nezih Yigitbasi
• Created: 13/Apr/15 17:43
• Updated: 02/Mar/16 18:49
• Resolved: 04/Aug/15 01:05

Description

The Hive CLI takes a long time to start when there is a large number of databases in the DW. I think the root cause is the way permanent UDFs are loaded from the metastore. When I looked at the logs and the source code I see that at startup Hive first gets all the databases from the metastore and then for each database it makes a metastore call to get the permanent functions for that database see Hive.java . So the number of metastore calls made is in the order of the number of databases. In production we have several hundreds of databases so Hive makes several hundreds of RPC calls during startup, taking 30+ seconds.

Issue Links

• is related to: HIVE-10288 Cannot call permanent UDFs
• is related to: HIVE-13132 Hive should lazily load and cache metastore (permanent) functions