[HBASE-3433] Remove the KV copy of every KV in Scan; introduced by HBASE-3232

• Type: Improvement
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 0.92.0, 0.94.0
• Component/s: Performance, regionserver
• Hadoop Flags: Incompatible change, Reviewed
• Assignee: Lars Hofhansl
• Reporter: Michael Stack
• Created: 08/Jan/11 20:00
• Updated: 12/Oct/12 05:34
• Resolved: 11/Nov/11 23:36

Description

Here is offending code from inside in StoreScanner#next:

      // kv is no longer immutable due to KeyOnlyFilter! use copy for safety
      KeyValue copyKv = new KeyValue(kv.getBuffer(), kv.getOffset(), kv.getLength());

This looks wrong given philosophy up to this has been avoidance of garbage-making copies.

Maybe this has been looked into before and this is the only thing to be done but why is KeyOnlyFilter not making copies rather than mutating originals?

Making this critical against 0.92.