[LUCENE-4203] Add IndexWriter.tryDeleteDocument, to delete by document id when possible

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0-BETA, 6.0
• Component/s: core/index
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Michael McCandless
• Created: 09/Jul/12 19:21
• Updated: 28/Aug/22 13:21
• Resolved: 02/Aug/12 23:06

Description

Spinoff from LUCENE-4069.

In that use case, where the app needs to first lookup a document, then
call updateDocument, it's wasteful today because the relatively costly
lookup (by a primary key field, eg "id") is done twice.

But, since you already resolved the PK to docID on the first lookup,
it would be nice to then delete by that docID and then you can call
addDocument instead.

So I worked out a rough start at this, by adding
IndexWriter.tryDeleteDocument. It'd be a very expert API: it takes a
SegmentInfo (referencing the segment that contains the docID), and as
long as that segment hasn't yet been merged away, it will mark the
document for deletion and return true (success). If it has been
merged away it returns false and the app must then delete-by-term. It
only works if the writer is in NRT mode (ie you've opened an NRT
reader).

In LUCENE-4069 using tryDeleteDocument gave a ~20% net speedup.

I think tryDeleteDocument would also be useful when Solr "updates" a
document by loading all stored fields, changing them, and calling
updateDocument.