[CASSANDRA-16] Memory efficient compactions

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.7 beta 1

Environment

All

• Assignee: Jonathan Ellis
• Reporter: Sandeep Tata
• Created: 27/Mar/09 01:12
• Updated: 28/Oct/15 16:14
• Resolved: 16/Jun/10 15:33

Description

The basic idea is to allow rows to get large enough that they don't have to fit in memory entirely, but can easily fit on a disk. The compaction algorithm today de-serializes the entire row in memory before writing out the compacted SSTable (see ColumnFamilyStore.doCompaction() and associated methods).

The requirement is to have a compaction method with a lower memory requirement so we can support rows larger than available main memory. To re-use the old FB example, if we stored a user's inbox in a row, we'd want the inbox to grow bigger than memory so long as it fit on disk.

Issue Links

• is blocked by: CASSANDRA-777 Extract SSTable interfaces to allow for alternative implementations
• is blocked by: CASSANDRA-847 Make the reading half of compactions memory-efficient