test

cassandra-cql-tips

Cassandra CQL Sample

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

CREATE TABLE sox.audit_history (
    hash_code text,
    cm_num text,
    message text,
    tag text,
    PRIMARY KEY (hash_code, cm_num)
) WITH CLUSTERING ORDER BY (cm_num ASC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
    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';

Cassandra FAQ

Simple Strategy

Assign the same replication factor to the entire cluster. For Test and Dev envs only.

Replication Factor

How many times the data is replicated across the clusters

Need at least 3 nodes if this value is set to 3.

Durable Writes

Bypass the commit log when writing to the keyspace if set to false.

NEVER disable it when using Simple Strategy.

Bloom Filter FP Chance

False-positive probability for SSTable bloom filter.

checks if the row exists before executing disk I/O

0 enables with the largest possible bloom filter and uses the most memory.

1.0 disables it.

Default: 0.01

Recommended: 0.1

Caching

Optimize the memory usage of tables.

will be weighted by size and frequency.

work with cassandra.yml

Compaction

Compression

CRC Check Chance

dclocal_read_repair_chance

Probability that a successful read operation triggers a read repair

limited to replicas in the same DC as the coordinator

default_time_to_live

max: 20 years in second

disabled: 0

a new TTL timestamp is calculated when the data is updated and the row is removed after all the data expires

gc_grace_seconds

GC: Garbage Collection

Tombstone: Deletion marker

data is marked with a Tombstone -> wait some time -> eligible for gc !

this config is about how long it should wait

Default: 10 days in second

memtable_flush_period_in_ms

Memtables:

Milliseconds before memtables associated with the table are flushed

max_index-interval

min_index_interval

read_repair_chance

similar to dclocal_read_repair_chance, but this repair is not limited to replicas in the same DC as the coordinator

speculative_retry

not configured variables

dclocal_read_repair_chance

read_repair_chance

memtable_flush_period_in_ms

Reference

https://docs.datastax.com/en/cql-oss/3.3/cql/cql_reference/cqlCreateTable.html#cqlCreateTable