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https://issues.apache.org/jira/browse/CASSANDRA-6654?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13910586#comment-13910586
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Keith Wright commented on CASSANDRA-6654:
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Happy to! Each row is a combination of several writes due to the inability to
set various TTLs per column via CQL3 (we are using the datastax driver).
Whenever writing sku_time data, we ALWAYS set a TTL to 28 days and same for
values but at 7 days. When writing other, data we either TTL to 6 months or
provide none (~95% would be with the 6 month TTL). Couple of things to note:
- approximately 3 weeks ago we increased our SSTable size from 64 to 160 MB but
we did not force a recompaction
- approximately 8 weeks ago we temporarily increased the gc_grace_seconds from
a day to 4 weeks due to a node going down. Approximately 3 weeks ago we reset
the gc_grace_seconds back to 1 day.
It "feels" like the data explosion corresponds with the increase of gc grace
seconds. Is it possible that changing the value back is not being honored?
Thanks!!!
> Droppable tombstones are not being removed from LCS table despite being above
> 20%
> ---------------------------------------------------------------------------------
>
> Key: CASSANDRA-6654
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6654
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Environment: 1.2.13 VNodes with murmur3
> Reporter: Keith Wright
> Assignee: Russ Hatch
> Attachments: Screen Shot 2014-02-05 at 9.38.20 AM.png
>
>
> JMX is showing that one of our CQL3 LCS tables has a droppable tombstone
> ratio above 20% and increasing (currently at 28%). Compactions are not
> falling behind and we are using the OOTB setting for this feature so I would
> expect not to go above 20% (will attach screen shot from JMX). Table
> description:
> CREATE TABLE global_user (
> user_id timeuuid,
> app_id int,
> type text,
> name text,
> extra_param map<text, text>,
> last timestamp,
> paid boolean,
> sku_time map<text, timestamp>,
> values map<timestamp, float>,
> PRIMARY KEY (user_id, app_id, type, name)
> ) WITH
> bloom_filter_fp_chance=0.100000 AND
> caching='KEYS_ONLY' AND
> comment='' AND
> dclocal_read_repair_chance=0.000000 AND
> gc_grace_seconds=86400 AND
> read_repair_chance=0.100000 AND
> replicate_on_write='true' AND
> populate_io_cache_on_flush='false' AND
> compaction={'sstable_size_in_mb': '160', 'class':
> 'LeveledCompactionStrategy'} AND
> compression={'chunk_length_kb': '8', 'crc_check_chance': '0.1',
> 'sstable_compression': 'LZ4Compressor'};
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