[HBASE-9132] Use table dir modtime to avoid scanning table dir to check cached table descriptor in 0.94

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.94.11
• Hadoop Flags: Reviewed
• Assignee: Dave Latham
• Reporter: Dave Latham
• Created: 05/Aug/13 23:53
• Updated: 21/Aug/13 00:08
• Resolved: 06/Aug/13 16:20

Description

As described in HBASE-8778, anything that needs to read table descriptors (such as region assignments) currently results in a table directory scan which is slow on tables with many regions. HBASE-8778 moved the table descriptors to a subdir for 0.96+. For 0.94 a smaller change that is safe with rolling restarts is to cache the directory modtime and use the cached table descriptor if the directory modtime has not changed since a table descriptor change always changes the directory.

Issue Links

• is duplicated by: HBASE-9133 Use table dir modtime to avoid scanning table dir to check cached table descriptor
• relates to: HBASE-8778 Region assigments scan table directory making them slow for huge tables