[LUCENE-2205] Rework of the TermInfosReader class to remove the Terms[], TermInfos[], and the index pointer long[] and create a more memory efficient data structure.

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.5, 4.0-ALPHA
• Component/s: core/index

Environment

Java5

• Lucene Fields: New, Patch Available
• Assignee: Michael McCandless
• Reporter: Aaron McCurry
• Created: 13/Jan/10 08:28
• Updated: 24/Oct/22 13:02
• Resolved: 27/Oct/11 20:47

Description

Basically packing those three arrays into a byte array with an int array as an index offset.

The performance benefits are stagering on my test index (of size 6.2 GB, with ~1,000,000 documents and ~175,000,000 terms), the memory needed to load the terminfos into memory were reduced to 17% of there original size. From 291.5 MB to 49.7 MB. The random access speed has been made better by 1-2%, load time of the segments are ~40% faster as well, and full GC's on my JVM were made 7 times faster.

I have already performed the work and am offering this code as a patch. Currently all test in the trunk pass with this new code enabled. I did write a system property switch to allow for the original implementation to be used as well.

-Dorg.apache.lucene.index.TermInfosReader=default or small

I have also written a blog about this patch here is the link.

http://www.nearinfinity.com/blogs/aaron_mccurry/my_first_lucene_patch.html