[jira] [Comment Edited] (CASSANDRA-8371) DateTieredCompactionStrategy is always compacting

["Jonathan Shook (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14230247#comment-14230247 ] 

Jonathan Shook edited comment on CASSANDRA-8371 at 12/1/14 6:59 PM:
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Also, using a different field allows us to require a proper time unit suffix, so the more uniform field names could throw a validation exception with a helpful message if it wasn't provided.


was (Author: jshook):
Also, using a different field allows us to require a proper time unit suffix, so the more uniform field names could throw a validation exception with a helpful message.

> DateTieredCompactionStrategy is always compacting 
> --------------------------------------------------
>
>                 Key: CASSANDRA-8371
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8371
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: mck
>            Assignee: Björn Hegerfors
>              Labels: compaction, performance
>         Attachments: java_gc_counts_rate-month.png, read-latency-recommenders-adview.png, read-latency.png, sstables-recommenders-adviews.png, sstables.png, vg2_iad-month.png
>
>
> Running 2.0.11 and having switched a table to [DTCS|https://issues.apache.org/jira/browse/CASSANDRA-6602] we've seen that disk IO and gc count increase, along with the number of reads happening in the "compaction" hump of cfhistograms.
> Data, and generally performance, looks good, but compactions are always happening, and pending compactions are building up.
> The schema for this is 
> {code}CREATE TABLE search (
>   loginid text,
>   searchid timeuuid,
>   description text,
>   searchkey text,
>   searchurl text,
>   PRIMARY KEY ((loginid), searchid)
> );{code}
> We're sitting on about 82G (per replica) across 6 nodes in 4 DCs.
> CQL executed against this keyspace, and traffic patterns, can be seen in slides 7+8 of https://prezi.com/b9-aj6p2esft/
> Attached are sstables-per-read and read-latency graphs from cfhistograms, and screenshots of our munin graphs as we have gone from STCS, to LCS (week ~44), to DTCS (week ~46).
> These screenshots are also found in the prezi on slides 9-11.
> [~pmcfadin], [~Bj0rn], 
> Can this be a consequence of occasional deleted rows, as is described under (3) in the description of CASSANDRA-6602 ?



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