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https://issues.apache.org/jira/browse/CASSANDRA-11383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15202934#comment-15202934
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Pavel Yaskevich commented on CASSANDRA-11383:
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[~doanduyhai] Let me first elaborate what I mean by "it's not sparse" - SPARSE
meant to be used when there are a lot index *values* and each of the values has
*less than 5 keys* so it's *SPARSE*ly found in the index. SPARSE have to do
more with keys/tokens than values, that's why example uses "created_at" since
that would have a lot of values and each of the values would, most likely, only
have a single token/key attached to it. We actually detect this situation and
actual index is going to be constructed correctly even if SPARSE mode was set
on not sparse column.
Regarding LCS - it's LeveledCompactionStrategy where you can set maximum
sstable size, I would suggest you make it something like 1G or less because
stitching and OOM you see is directly related to the size of sstable file.
Meanwhile I working on the fix for current situation.
> SASI index build leads to massive OOM
> -------------------------------------
>
> 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
> Attachments: CASSANDRA-11383.patch, 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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