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From Nawab Zada Asad Iqbal <khi...@gmail.com>
Subject Re: Are flushed (but not committed yet) segments mutable?
Date Sun, 11 Feb 2018 06:29:01 GMT
Thanks Erick!

On Sat, Feb 10, 2018 at 11:37 PM, Erick Erickson <erickerickson@gmail.com>
wrote:

> "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 <khichi@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
>

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