"I also see some segment merges before the hard-commit executes, which make me think that flush converts the in-memory data-structures into Lucene"
That's my understanding. Essentially each flush creates a new segment that gets merged sometime. "How is a flushed-but-not-committed segment different from a committed segment?" In a nutshell, it hasn't been added to the "segments_n" file, which contains a list of all of the segments as of the last commit point. Segments added for whatever reason since the last hard commit aren't added to that file. So say Solr is killed before committing. When it restarts it sees the segments_n file that contains the old "picture" of the index. If tlogs are around, then Solr replays the documents since that point. Best, Erick On Fri, Feb 9, 2018 at 8:07 PM, Nawab Zada Asad Iqbal <khi...@gmail.com> wrote: > Hi, > > When a segment is flushed to disk because it is exceeding available memory, > is it sill updated when new documents are added? I also read somewhere that > a segment is not committed even if it is flushed. How is a > flushed-but-not-committed segment different from a committed segment? > > For example, my hard-commit is scheduled for every 30 seconds, but many > segments are flushed during this interval. Are they flushed as in-memory > data structures (which will keep them optimal for updates) or are they > immutable? > > I also see some segment merges before the hard-commit executes, which make > me think that flush converts the in-memory data-structures into Lucene > segment. > > Thanks > Nawab
