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From "Jordan West (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11383) Avoid index segment stitching in RAM which lead to OOM on big SSTable files
Date Tue, 29 Mar 2016 21:54:25 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15216917#comment-15216917
] 

Jordan West commented on CASSANDRA-11383:
-----------------------------------------

The docs look pretty comprehensive. Thanks! I'll make a more detailed pass through them when
I get a chance. I think the only thing we would like to clarify, based on the discussion in
this ticket, is when to choose {{SPARSE}} over {{PREFIX}} for numerical data. My last comment
(https://issues.apache.org/jira/browse/CASSANDRA-11383?focusedCommentId=15216337&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15216337)
mentions a way to do that. 

Otherwise, specific to {{SPARSE}} the only recommendation I have is that the {{SPARSE}} example
on the "CREATE CUSTOM INDEX (SASI)" page (https://docs.datastax.com/en/cql/3.3/cql/cql_reference/refCreateSASIIndex.html)
uses {{age}}, which typically would not be a good candidate for a {{SPARSE}} index (the answer
to question number 2 in my linked comment would be: no, there are not millions of ages with
each term having a small number of matching keys). 

> Avoid index segment stitching in RAM which lead to OOM on big SSTable files 
> ----------------------------------------------------------------------------
>
>                 Key: CASSANDRA-11383
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11383
>             Project: Cassandra
>          Issue Type: Bug
>          Components: CQL
>         Environment: C* 3.4
>            Reporter: DOAN DuyHai
>            Assignee: Jordan West
>              Labels: sasi
>             Fix For: 3.5
>
>         Attachments: CASSANDRA-11383.patch, SASI_Index_build_LCS_1G_Max_SSTable_Size_logs.tar.gz,
new_system_log_CMS_8GB_OOM.log, system.log_sasi_build_oom
>
>
> 13 bare metal machines
> - 6 cores CPU (12 HT)
> - 64Gb RAM
> - 4 SSD in RAID0
>  JVM settings:
> - G1 GC
> - Xms32G, Xmx32G
> Data set:
>  - ≈ 100Gb/per node
>  - 1.3 Tb cluster-wide
>  - ≈ 20Gb for all SASI indices
> C* settings:
> - concurrent_compactors: 1
> - compaction_throughput_mb_per_sec: 256
> - memtable_heap_space_in_mb: 2048
> - memtable_offheap_space_in_mb: 2048
> I created 9 SASI indices
>  - 8 indices with text field, NonTokenizingAnalyser,  PREFIX mode, case-insensitive
>  - 1 index with numeric field, SPARSE mode
>  After a while, the nodes just gone OOM.
>  I attach log files. You can see a lot of GC happening while index segments are flush
to disk. At some point the node OOM ...
> /cc [~xedin]



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