Considerations about setting maxMergedSegmentMB

[Isaac Hebsh <is...@gmail.com>]

Hi,
Trying to solve query performance issue, we suspect on the number of index
segments, which might slow the query (due to I/O seeks, happens for each
term in the query, multiplied by number of segments).
We are on Solr 4.3 (TieredMergePolicy with mergeFactor of 4).

We can reduce the number of segments by enlarging maxMergedSegmentMB, from
the default 5GB to something bigger (10GB, 15GB?).

What are the side effects, which should be considered when doing it?
Did anyone changed this setting in PROD for a while?

Re: Considerations about setting maxMergedSegmentMB

[Erick Erickson <er...@gmail.com>]

Before going there, you can do a really simple test. Turn off
indexing and then issues a optimize/force-merge. After it
completes (and it may take quite some time) measure your
performance again to see fi this is on the right track.

Best,
Erick

On Mon, Sep 30, 2013 at 1:31 PM, Isaac Hebsh <is...@gmail.com> wrote:
> Hi,
> Trying to solve query performance issue, we suspect on the number of index
> segments, which might slow the query (due to I/O seeks, happens for each
> term in the query, multiplied by number of segments).
> We are on Solr 4.3 (TieredMergePolicy with mergeFactor of 4).
>
> We can reduce the number of segments by enlarging maxMergedSegmentMB, from
> the default 5GB to something bigger (10GB, 15GB?).
>
> What are the side effects, which should be considered when doing it?
> Did anyone changed this setting in PROD for a while?