# Optimization Questions **URL:** \ **Category:** Elasticsearch\ **Created:** [August 16, 2014, 3:01am UTC](https://discuss.elastic.co/t/optimization-questions/19308 "2014-08-16T03:01:04Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Gregory\_Sutcliffe](https://avatars.discourse-cdn.com/v4/letter/g/e99b99/32.png) [@Gregory\_Sutcliffe](https://discuss.elastic.co/u/Gregory_Sutcliffe)\ **Post date:** [August 16, 2014, 3:01am UTC](https://discuss.elastic.co/t/optimization-questions/19308/1 "2014-08-16T03:01:04Z")
Hey Guys, We were doing some updates to our es(1.3.1) clusters recently and had some questions about \_optimize. We optimized with max\_num\_segments 1 and we're still seeing ~25 segments per shard. The index that was optimized had no writes going to it during the time, it was actually freshly re-opened after an upgrade. Also, are there any tricks to seeing when an optimize is done other that watching merges stats and disk IO? Maybe some data in marvel? Thanks for your assistance, Greg -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![andrew](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@andrew](https://discuss.elastic.co/u/andrew)\ **Post date:** [August 18, 2014, 4:33pm UTC](https://discuss.elastic.co/t/optimization-questions/19308/2 "2014-08-18T16:33:41Z")
Hi Greg, I believe max\_num\_segments is technically a hint that can be overridden by the merge algorithm if it decides to. You might try simply re-running the optimize again to get from ~25 down closer to 1. Sorry but I don't know of any way to see when the optimize is finished - it's really just forcing a merge so looking at merge stats is what you want. Hope that helps. Andrew On Aug 15, 2014, at 8:01 PM, Gregory Sutcliffe [gsutcliffe@publishthis.com](mailto:gsutcliffe@publishthis.com) wrote: > Hey Guys, > We were doing some updates to our es(1.3.1) clusters recently and had some questions about \_optimize. We optimized with max\_num\_segments 1 and we're still seeing ~25 segments per shard. The index that was optimized had no writes going to it during the time, it was actually freshly re-opened after an upgrade. Also, are there any tricks to seeing when an optimize is done other that watching merges stats and disk IO? Maybe some data in marvel? > > Thanks for your assistance, > Greg > > -- > You received this message because you are subscribed to the Google Groups "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com). > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com](https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![mikemccand](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@mikemccand](https://discuss.elastic.co/u/mikemccand)\ **Post date:** [August 19, 2014, 12:53pm UTC](https://discuss.elastic.co/t/optimization-questions/19308/3 "2014-08-19T12:53:39Z")
You could turn on TRACE logging for the "lucene.iw" component. This will give tons of details about what merges are being done. Normally, if there are no writes going to the index at the same time, an optimize with max\_num\_segments=1 really should get down to 1 segment in the end ... not sure why it isn't in your case. Was there a refresh after the optimize? Mike McCandless [http://blog.mikemccandless.com](http://blog.mikemccandless.com) On Mon, Aug 18, 2014 at 12:33 PM, Andrew Selden \< [andrew.selden@elasticsearch.com](mailto:andrew.selden@elasticsearch.com)\> wrote: > Hi Greg, > > I believe max\_num\_segments is technically a hint that can be overridden by > the merge algorithm if it decides to. You might try simply re-running the > optimize again to get from ~25 down closer to 1. Sorry but I don’t know of > any way to see when the optimize is finished - it’s really just forcing a > merge so looking at merge stats is what you want. > > Hope that helps. > Andrew > > On Aug 15, 2014, at 8:01 PM, Gregory Sutcliffe [gsutcliffe@publishthis.com](mailto:gsutcliffe@publishthis.com) > wrote: > > Hey Guys, > We were doing some updates to our es(1.3.1) clusters recently and had some > questions about \_optimize. We optimized with max\_num\_segments 1 and we're > still seeing ~25 segments per shard. The index that was optimized had no > writes going to it during the time, it was actually freshly re-opened after > an upgrade. Also, are there any tricks to seeing when an optimize is done > other that watching merges stats and disk IO? Maybe some data in marvel? > > Thanks for your assistance, > Greg > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com) > [https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/17622c72-f004-4fda-92fb-dda393a64807%40googlegroups.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com](https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com) > [https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/88238DE4-AFC4-41D0-B495-ED9938D7CB9C%40elasticsearch.com?utm_medium=email&utm_source=footer) > . > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAD7smRcMuZHzruXtto\_K%3Dw7uNqABRzLe3rjSgd182iF6xBi5Gg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAD7smRcMuZHzruXtto_K%3Dw7uNqABRzLe3rjSgd182iF6xBi5Gg%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 1:07am UTC](https://discuss.elastic.co/t/optimization-questions/19308/4 "2017-07-06T01:07:45Z")