# Lucene 4.1 AnalyzingSuggester in ES having persistable FST **URL:** \ **Category:** Elasticsearch\ **Created:** [September 12, 2013, 7:41am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566 "2013-09-12T07:41:51Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Chetana](https://avatars.discourse-cdn.com/v4/letter/c/dbc845/32.png) [@Chetana](https://discuss.elastic.co/u/Chetana)\ **Post date:** [September 12, 2013, 7:41am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/1 "2013-09-12T07:41:51Z")
FST built for my application is large. Is there any work done by someone to store FST generated to index repository or to any other persistent cache ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [September 12, 2013, 7:56am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/2 "2013-09-12T07:56:25Z")
Is this true? FST are not persistent, they do not survive node restarts? Jörg -- 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Chetana](https://avatars.discourse-cdn.com/v4/letter/c/dbc845/32.png) [@Chetana](https://discuss.elastic.co/u/Chetana)\ **Post date:** [September 12, 2013, 8:44am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/3 "2013-09-12T08:44:19Z")
I believe Lucene's default implementation is in-memory. Someone please confirm whether elasticsearch has overriden this behavior On Thursday, September 12, 2013 1:26:25 PM UTC+5:30, Jörg Prante wrote: > Is this true? FST are not persistent, they do not survive node restarts? > > Jörg -- 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Clinton\_Gormley](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@Clinton\_Gormley](https://discuss.elastic.co/u/Clinton_Gormley)\ **Post date:** [September 12, 2013, 12:33pm UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/4 "2013-09-12T12:33:33Z")
In Elasticsearch, the analyzing suggester writes its FST per-segment at index time. So we can just load the FST from disk the first time it is used. clint On 12 September 2013 10:44, Chetana [ambha.career@gmail.com](mailto:ambha.career@gmail.com) wrote: > I believe Lucene's default implementation is in-memory. Someone please > confirm whether elasticsearch has overriden this behavior > > On Thursday, September 12, 2013 1:26:25 PM UTC+5:30, Jörg Prante wrote: > > > Is this true? FST are not persistent, they do not survive node restarts? > > > > Jörg > > > > -- > > 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). > > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![simonw\_2](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/simonw_2/32/1130_2.png) [@simonw\_2](https://discuss.elastic.co/u/simonw_2)\ **Post date:** [September 13, 2013, 7:34am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/5 "2013-09-13T07:34:38Z")
The FSTs are persistent on disk - they can be recovered via the ES recovery mechanism and they are durable. The FSTs are in memory when you read them at query time but that doesn't mean they are lost on node restart. The Lucene index also uses FSTs which are written to disk in the term dictionary and when you open the index they are pulled into memory. simon On Thursday, September 12, 2013 2:33:33 PM UTC+2, Clinton Gormley wrote: > In Elasticsearch, the analyzing suggester writes its FST per-segment at > index time. So we can just load the FST from disk the first time it is > used. > > clint > > On 12 September 2013 10:44, Chetana \<[ambha....@gmail.com](mailto:ambha....@gmail.com) \\>wrote: > > > I believe Lucene's default implementation is in-memory. Someone please > > confirm whether elasticsearch has overriden this behavior > > > > On Thursday, September 12, 2013 1:26:25 PM UTC+5:30, Jörg Prante wrote: > > > > > Is this true? FST are not persistent, they do not survive node restarts? > > > > > > Jörg > > > > > > -- > > > 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 [elasticsearc...@googlegroups.com](mailto:elasticsearc...@googlegroups.com) \. > > > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**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, 2:16am UTC](https://discuss.elastic.co/t/lucene-4-1-analyzingsuggester-in-es-having-persistable-fst/13566/6 "2017-07-06T02:16:44Z")