Nhat Nguyen 75719ac71b
Make _id terms optional in segment containing only noop (#30409)
Previously only index and delete operations are indexed into Lucene,
therefore every segment should have both _id and _version terms as these
operations contain both terms. However, this is no longer guaranteed
after noop is also indexed into Lucene. A segment which contains only
no-ops does not have neither _id or _version because a no-op does not
contain these terms.

This change adds a dummy version to no-ops and makes _id terms optional
in PerThreadIDVersionAndSeqNoLookup.

Relates #30226
2018-05-08 13:38:40 -04:00
..