[LUCENE-4509] Make CompressingStoredFieldsFormat the new default StoredFieldsFormat impl

• Type: Wish
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 4.1
• Component/s: core/store
• Lucene Fields: New
• Assignee: Adrien Grand
• Reporter: Adrien Grand
• Created: 26/Oct/12 18:03
• Updated: 28/Aug/22 13:30
• Resolved: 13/Nov/12 15:52

Description

What would you think of making CompressingStoredFieldsFormat the new default StoredFieldsFormat?

Stored fields compression has many benefits :

• it makes the I/O cache work for us,
• file-based index replication/backup becomes cheaper.

Things to know:

• even with incompressible data, there is less than 0.5% overhead with LZ4,
• LZ4 compression requires ~ 16kB of memory and LZ4 HC compression requires ~ 256kB,
• LZ4 uncompression has almost no memory overhead,
• on my low-end laptop, the LZ4 impl in Lucene uncompresses at ~ 300mB/s.

I think we could use the same default parameters as in CompressingCodec :

• LZ4 compression,
• in-memory stored fields index that is very memory-efficient (less than 12 bytes per block of compressed docs) and uses binary search to locate documents in the fields data file,
• 16 kB blocks (small enough so that there is no major slow down when the whole index would fit into the I/O cache anyway, and large enough to provide interesting compression ratios ; for example Robert got a 0.35 compression ratio with the geonames.org database).

Any concerns?