[LUCENE-8932] Allow BKDReader packedIndex to be off heap

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 8.4
• Assignee: Unassigned
• Reporter: Jack Conradson
• Created: 23/Jul/19 23:44
• Updated: 28/Aug/22 15:49
• Resolved: 25/Oct/19 09:22

Description

This change modifies BKDReader to read the packedIndex bytes off heap rather than load them all on heap at a single time.

Questions for discussion:

1. Should BKDReader only support packedIndex off heap?
2. If not, how should the choice be made?

Using luceneutils IndexAndSearchOpenStreetMaps present the following test results:

with -box -points (patch)

READER MB: 1.1345596313476562

BEST M hits/sec: 73.34277344984474
BEST QPS: 74.63011169783009

with -box -points (original)

READER MB: 1.7249317169189453

BEST M hits/sec: 73.77125157623486
BEST QPS: 75.06611062353801

with -nearest 10 -points (patch)

READER MB: 1.1345596313476562

BEST M hits/sec: 0.013586298373879497
BEST QPS: 1358.6298373879497

with -nearest 10 -points (original)

READER MB: 1.7249317169189453

BEST M hits/sec: 0.01445208197367343
BEST QPS: 1445.208197367343

with -box -geo3d (patch)

READER MB: 1.1345596313476562

BEST M hits/sec: 39.84968715299074
BEST QPS: 40.54914292796736

with -box -geo3d (original)

READER MB: 1.7456226348876953

BEST M hits/sec: 40.45051734329004
BEST QPS: 41.160519101846695