[jira] [Created] (LUCENE-7390) Let BKDWriter use temp heap for sorting points in proportion to IndexWriter's indexing buffer

["Michael McCandless (JIRA)" <ji...@apache.org>]

Michael McCandless created LUCENE-7390:
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             Summary: Let BKDWriter use temp heap for sorting points in proportion to IndexWriter's indexing buffer
                 Key: LUCENE-7390
                 URL: https://issues.apache.org/jira/browse/LUCENE-7390
             Project: Lucene - Core
          Issue Type: Improvement
            Reporter: Michael McCandless
             Fix For: master (7.0), 6.2


With Lucene's default codec, when writing dimensional points, we only give {{BKDWriter}} 16 MB heap to use for sorting, regardless of how large IW's indexing buffer is.  A custom codec can change this but that's a little steep.

I've been testing indexing performance on a points-heavy dataset, 1.2 billion taxi rides from http://www.nyc.gov/html/tlc/html/about/trip_record_data.shtml , indexing with a 1 GB IW buffer, and the small 16 MB heap limit causes clear performance problems because flushing the large segments forces {{BKDwriter}} to switch to offline sorting which causes the DWPTs take too long to flush.  They then fall behind, and Lucene does a hard stall on incoming indexing threads until they catch up.

[~rcmuir] had a simple idea to let IW pass the allowed temp heap usage to {{PointsWriter.writeField}}.




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