Hey Rahul,
Each partition has around 10 cluster keys. Based on nodetool, I can roughly
estimate partition size to be less than 1KB.
On Mon, Feb 5, 2018 at 5:37 PM, mohsin k <moshinkarova...@gmail.com> wrote:
> Hey Nicolas,
>
> My goal is to reduce latency as much as possible. I did wait for warmup.
> The test ran for more than 15mins, I am not sure why it shows 2mins though.
>
>
>
> On Mon, Feb 5, 2018 at 5:25 PM, Rahul Singh <rahul.xavier.si...@gmail.com>
> wrote:
>
>> What is the average size of your partitions / rows. 1GB may not be enough.
>>
>> Rahul
>>
>> On Feb 5, 2018, 6:52 AM -0500, mohsin k <moshinkarova...@gmail.com>,
>> wrote:
>>
>> Hi,
>>
>> I have been looking into different configurations for tuning my cassandra
>> servers. So, initially I loadtested server using cassandra-stress tool,
>> with default configs and then tuning one by one config to measure impact of
>> change. First config, I tried was setting "*row_cache_size_in_mb*" to
>> 1000 (MB) in yaml, adding caching {'keys': 'ALL', *'rows_per_partition':
>> 'ALL'*}. After changing these configs, I observed that latency has
>> increased rather than decreasing. It would be really helpful if I get to
>> understand why is this the case and what steps must be taken to decrease
>> the latency.
>>
>> I am running a cluster with 4 nodes.
>>
>> Following is my schema:
>>
>> CREATE TABLE stresstest.user_to_segment (
>> userid text,
>> segmentid text,
>> PRIMARY KEY (userid, segmentid)
>> ) WITH CLUSTERING ORDER BY (segmentid DESC)
>> AND bloom_filter_fp_chance = 0.1
>> AND caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'}
>> AND comment = 'A table to hold blog segment user relation'
>> AND compaction = {'class': 'org.apache.cassandra.db.compa
>> ction.LeveledCompactionStrategy'}
>> AND compression = {'chunk_length_in_kb': '64', 'class': '
>> org.apache.cassandra.io.compress.LZ4Compressor'}
>> AND crc_check_chance = 1.0
>> 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 = '99PERCENTILE';
>>
>> Following are node specs:
>> RAM: 4GB
>> CPU: 4 Core
>> HDD: 250BG
>>
>>
>> Following is the output of 'nodetool info' after setting
>> row_cache_size_in_mb:
>>
>> ID : d97dfbbf-1dc3-4d95-a1d9-c9a8d22a3d32
>> Gossip active : true
>> Thrift active : false
>> Native Transport active: true
>> Load : 10.94 MiB
>> Generation No : 1517571163
>> Uptime (seconds) : 9169
>> Heap Memory (MB) : 136.01 / 3932.00
>> Off Heap Memory (MB) : 0.10
>> Data Center : dc1
>> Rack : rack1
>> Exceptions : 0
>> Key Cache : entries 125881, size 9.6 MiB, capacity 100 MiB,
>> 107 hits, 126004 requests, 0.001 recent hit rate, 14400 save period in
>> seconds
>> Row Cache : entries 125861, size 31.54 MiB, capacity 1000
>> MiB, 4262684 hits, 4388545 requests, 0.971 recent hit rate, 0 save
>> period in seconds
>> Counter Cache : entries 0, size 0 bytes, capacity 50 MiB, 0
>> hits, 0 requests, NaN recent hit rate, 7200 save period in seconds
>> Chunk Cache : entries 273, size 17.06 MiB, capacity 480 MiB,
>> 325 misses, 126623 requests, 0.997 recent hit rate, NaN microseconds miss
>> latency
>> Percent Repaired : 100.0%
>> Token : (invoke with -T/--tokens to see all 256 tokens)
>>
>>
>> Following is output of nodetool cfstats:
>>
>> Total number of tables: 37
>> ----------------
>> Keyspace : stresstest
>> Read Count: 4398162
>> Read Latency: 0.02184742626579012 ms.
>> Write Count: 0
>> Write Latency: NaN ms.
>> Pending Flushes: 0
>> Table: user_to_segment
>> SSTable count: 1
>> SSTables in each level: [1, 0, 0, 0, 0, 0, 0, 0, 0]
>> Space used (live): 11076103
>> Space used (total): 11076103
>> Space used by snapshots (total): 0
>> Off heap memory used (total): 107981
>> SSTable Compression Ratio: 0.5123353861375962
>> Number of partitions (estimate): 125782
>> Memtable cell count: 0
>> Memtable data size: 0
>> Memtable off heap memory used: 0
>> Memtable switch count: 2
>> Local read count: 4398162
>> Local read latency: 0.030 ms
>> Local write count: 0
>> Local write latency: NaN ms
>> Pending flushes: 0
>> Percent repaired: 0.0
>> Bloom filter false positives: 0
>> Bloom filter false ratio: 0.00000
>> Bloom filter space used: 79280
>> Bloom filter off heap memory used: 79272
>> Index summary off heap memory used: 26757
>> Compression metadata off heap memory used: 1952
>> Compacted partition minimum bytes: 43
>> Compacted partition maximum bytes: 215
>> Compacted partition mean bytes: 136
>> Average live cells per slice (last five minutes): 5.719932432432432
>> Maximum live cells per slice (last five minutes): 10
>> Average tombstones per slice (last five minutes): 1.0
>> Maximum tombstones per slice (last five minutes): 1
>> Dropped Mutations: 0
>>
>> Following are my results:
>> The blue graph is before setting row_cache_size_in_mb,
>> orange is after
>>
>> Thanks,
>> Mohsin
>>
>>
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>
