[#LUCENE-454] lazily create SegmentMergeInfo.docMap

Lucene - Java

lazily create SegmentMergeInfo.docMap

Created: 13/Oct/05 12:44 PM Updated: 28/Oct/05 12:52 PM

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Component/s:

None

Affects Version/s:

CVS Nightly - Specify date in submission

Fix Version/s:

1.9

Time Tracking:

Not Specified

File Attachments:

File Name	Date Attached	Attached By	Size
docMap.txt	2005-10-14 12:25 PM	Yonik Seeley	2 kB
docMap.txt	2005-10-13 12:49 PM	Yonik Seeley	2 kB

Resolution Date:

28/Oct/05 12:52 PM

Description

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Since creating the docMap is expensive, and it's only used during segment merging, not searching, defer creation until it is requested.

SegmentMergeInfo is also used in MultiTermEnum, the term enumerator for a MultiReader. TermEnum is used by queries such as PrefixQuery, RangeQuery, WildcardQuery, as well as RangeFilter, DateFilter, and sorting the first time (filling the FieldCache).

Performance Results:
A simple single field index with 555,555 documents, and 1000 random deletions was queried 1000 times with a PrefixQuery matching a single document.

Performance Before Patch:
indexing time = 121,656 ms
querying time = 58,812 ms

Performance After Patch:
indexing time = 121,000 ms
querying time = 598 ms

A 100 fold increase in query performance!

All lucene unit tests pass.

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Work Log

Change History

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Repository	Revision	Date	User	Message
ASF	#329068	Fri Oct 28 03:44:00 UTC 2005	yonik	speedup by deferring docMap and postings until needed - ~~LUCENE-454~~
				Files Changed
				MODIFY /lucene/java/trunk/src/java/org/apache/lucene/index/SegmentMergeInfo.java MODIFY /lucene/java/trunk/src/java/org/apache/lucene/index/SegmentMerger.java