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

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

    [ https://issues.apache.org/jira/browse/CASSANDRA-8371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14227940#comment-14227940 ] 

mck edited comment on CASSANDRA-8371 at 11/27/14 8:14 PM:
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( jira threaded comments [plugin|https://duckduckgo.com/l/?kh=-1&uddg=https%3A%2F%2Fmarketplace.atlassian.com%2Fplugins%2Fcom.atlassian.jira.threadedcomments.threaded-comments] would be so nice :-) )


Attached is graphs from another keyspace+table.
This data has TTL of 20 days, in total ~15Gb per replica.
It's part of the data created in preparation for the spark ALS recommendation model generation. It's created from pig jobs that run every minute or two. So 50Mb of data is collected in ~1.6hrs.

The schema is {code}CREATE TABLE ad_view (
  userid bigint,
  type text,
  last_update timestamp,
  itemid bigint,
  dummy text,
  PRIMARY KEY ((userid, type), last_update, itemid)
);{code}


was (Author: michaelsembwever):
( jira threaded comments [plugin|https://duckduckgo.com/l/?kh=-1&uddg=https%3A%2F%2Fmarketplace.atlassian.com%2Fplugins%2Fcom.atlassian.jira.threadedcomments.threaded-comments] would be so nice :-)


Attached is graphs from another keyspace+table.
This data has TTL of 20 days, in total ~15Gb per replica.
It's part of the data created in preparation for the spark ALS recommendation model generation. It's created from pig jobs that run every minute or two. So 50Mb of data is collected in ~1.6hrs.

The schema is {code}CREATE TABLE ad_view (
  userid bigint,
  type text,
  last_update timestamp,
  itemid bigint,
  dummy text,
  PRIMARY KEY ((userid, type), last_update, itemid)
);{code}

> 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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