[HBASE-9553] Pad HFile blocks to a fixed size before placing them into the blockcache

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Assignee: Unassigned
• Reporter: Lars Hofhansl
• Created: 17/Sep/13 00:18
• Updated: 16/Jun/22 18:06
• Resolved: 08/Dec/13 01:36

Description

In order to make it easy on the garbage collector and to avoid full compaction phases we should make sure that all (or at least a large percentage) of the HFile blocks as cached in the block cache are exactly the same size.

Currently an HFile block is typically slightly larger than the declared block size, as the block will accommodate that last KV on the block. The padding would be a ColumnFamily option. In many cases 100 bytes would probably be a good value to make all blocks exactly the same size (but of course it depends on the max size of the KVs).

This does not have to be perfect. The more blocks evicted and replaced in the block cache are of the exact same size the easier it should be on the GC.

Thoughts?