Cassandra - Map type read latency

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Cassandra - Map type read latency

Postby John » Wed Jun 03, 2015 4:53 pm

Hi All,


First of all thanks to everyone here who answers all our queries.

I am stucked in one of the points I hope people can get me out of my problem.

I have Apache 2.1 Cluster with 6 nodes and I have created a table with 3 columns..1st column as text type and other 2 are map type. When I insert data into table and read the data..for fetching 1 row it is taking around 20 milliseconds but if I create a table with text type for all the 3 columns then it is taking just 5 ms. Kindly suggest me were I am missing..why is it taking time if it is map type?? I am confused were to start the map type read latency.

Below are the cfstats and query:

Table:
PRODUCT_TYPE
SSTable count: 1
SSTables in each level: [1, 0, 0, 0, 0, 0, 0, 0, 0]
Space used (live): 81458
Space used (total): 81458
Space used by snapshots (total): 0
Off heap memory used (total): 87
SSTable Compression Ratio: 0.15090414689301526
Number of keys (estimate): 6
Memtable cell count: 0
Memtable data size: 0
Memtable off heap memory used: 0
Memtable switch count: 0
Local read count: 5
Local read latency: 22.494 ms
Local write count: 0
Local write latency: NaN ms
Pending flushes: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 16
Bloom filter off heap memory used: 8
Index summary off heap memory used: 15
Compression metadata off heap memory used: 64
Compacted partition minimum bytes: 73458
Compacted partition maximum bytes: 105778
Compacted partition mean bytes: 91087
Average live cells per slice (last five minutes): 1.0
Maximum live cells per slice (last five minutes): 1.0
Average tombstones per slice (last five minutes): 0.0
Maximum tombstones per slice (last five minutes): 0.0

CREATE TABLE TEST.PRODUCT_TYPE (
type text PRIMARY KEY,
col1 map<int, boolean>,
timestamp_map map<int, timestamp>
) WITH bloom_filter_fp_chance = 0.1
AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
AND comment = ''
AND compaction = {'min_threshold': '4', 'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy', '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 = 864000
AND max_index_interval = 2048
AND memtable_flush_period_in_ms = 0
AND min_index_interval = 128
AND read_repair_chance = 0.0
AND speculative_retry = '99.0PERCENTILE';


Thanks in advance for all your support and answers.

Thanks, John
John
 
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Joined: Wed Jun 03, 2015 4:48 pm

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