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From Venkatesh Arivazhagan <venkey.a...@gmail.com>
Subject Help with tombstones and compaction
Date Sun, 20 Sep 2015 21:48:01 GMT
Hi Guys,

I have a Cassandra 2.1.4 cluster with 14 nodes. I am using it primarily for
storing time series data collected via KairosDB.
The default TTL for data inserted into the column family named data_points
is 12hrs. I have also set the gc_grace_seconds to 12 hrs.
In-spite of this my disk space keeps on increasing and it looks like
tombstones are never dropped.

It looks like compactions are happening on a regular basis. The SSTable
count does not seem outrageous either. It is constantly between ~10 to ~22.

Am I doing anything wrong? Is there a way to mitigate this?

Attached:
* DESC output for my keyspace
* Disk usage graph
* LiveSSTable Count graph

--------------------------------------------------------------------------------------------------------------------------

CREATE KEYSPACE kairosdb WITH replication = {'class': 'SimpleStrategy',
'replication_factor': '3'}  AND durable_writes = true;

CREATE TABLE kairosdb.data_points (
    key blob,
    column1 blob,
    value blob,
    PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
    AND CLUSTERING ORDER BY (column1 ASC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = ''
    AND compaction = {'max_sstable_age_days': '365', 'base_time_seconds':
'3600', 'max_threshold': '32', 'timestamp_resolution': 'MILLISECONDS',
'enabled': 'true', 'tombstone_compaction_interval': '1', 'min_threshold':
'4', 'tombstone_threshold': '.1', 'class':
'org.apache.cassandra.db.compaction.DateTieredCompactionStrategy'}
    AND compression = {'sstable_compression':
'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 43200
    AND gc_grace_seconds = 43200
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.1
    AND speculative_retry = 'NONE';

CREATE TABLE kairosdb.row_key_index (
    key blob,
    column1 blob,
    value blob,
    PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
    AND CLUSTERING ORDER BY (column1 ASC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = ''
    AND compaction = {'min_threshold': '4', 'class':
'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32'}
    AND compression = {'sstable_compression':
'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 43200
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.1
    AND speculative_retry = 'NONE';

CREATE TABLE kairosdb.string_index (
    key blob,
    column1 text,
    value blob,
    PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
    AND CLUSTERING ORDER BY (column1 ASC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = ''
    AND compaction = {'min_threshold': '4', 'class':
'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32'}
    AND compression = {'sstable_compression':
'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 43200
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.1
    AND speculative_retry = 'NONE';
--------------------------------------------------------------------------------------------------------------------------

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