conf/cassandra.yaml:
cdc_enabled = false: Change data capture (CDC) provides a mechanism to flag
specific tables for archival as well as rejecting writes to those tables once a
configurable size-on-disk for the CDC log is reached. An operator can enable CDC on
a table by setting the table property cdc=true (either when creating the table or
altering it).
disk_optimization_strategy (ssd / spinning)
memtable_heap_space_in_mb: 2044
memtable_allocation_type: heap_buffers
- SimpleTopologyStrategy: A simple strategy that defines a replication factor for
data to be spread across the entire cluster.
- NetworkTopologyStrategy: A production ready replication strategy that allows
to set the replication factor independently for each data-center. The rest of the
sub-options are key-value pairs where a key is a data-center name and its
value is the associated replication factor.
partition key is uco here.
clustering column is field here.
CREATE TABLE people (
id int,
surname text,
fullname text,
email text,
salary float,
address map<text,text>,
PRIMARY KEY (id, surname)
);
1/ select count(*) from people ;
2/ may require to create an index! CREATE INDEX ON people(surname);
3/ the same as 2/
4/ it requires to have the primary key to be (surname,id)!!!
5/ update people using ttl 60 set email='to expire' where id=1190 and
fullname=’Wesley Rodgers';
6/ delete address[‘number’] from people where id=1190 and fullname=’Wesley
Rodgers';
7/ you cannot do it with update -- you have to reinsert the record with TTL set.
Some columns can be declared as STATIC in a table definition. A column that is
static will be “shared” by all the rows belonging to the same partition (having the
same partition key).
SELECT TTL(email),WRITETIME(email) from people limit 3;
DELETE scores[1] FROM plays WHERE id = '123-afde';
CREATE INDEX <index_name> ON <table_name> (ENTRIES(<map_column>));
Cassandra does not support selecting map members directly,. but UDF can be
defined:
-- Add UDF to keyspace that can lookup Map values using a key where the key and
value are both of type text
CREATE OR REPLACE FUNCTION lookup(k text, m map<text,tex>) RETURNS
NULL ON NULL INPUT RETURNS TEXT LANGUAGE Java
AS '
return (String)m.get(k);
';
Output of cassandra test:
Data Description
total ops Running total number of operations during the run.
op/s Number of operations per second performed during the
run.
pk/s Number of partition operations per second performed
during the run.
row/s Number of row operations per second performed during
the run.
mean Average latency in milliseconds for each operation
during that run.
med Median latency in milliseconds for each operation
during that run.
.95 95% of the time the latency was less than the number
displayed in the column.
.99 99% of the time the latency was less than the number
displayed in the column.
.999 99.9% of the time the latency was less than the number
displayed in the column.
max Maximum latency in milliseconds.
time Total operation time.
stderr Standard error of the mean. It is a measure of
confidence in the average throughput number; the smaller the number, the more
accurate the measure of the cluster's performance.
gc: # Number of garbage collections.
max ms Longest garbage collection in milliseconds.
sum ms Total of garbage collection in milliseconds.
sdv ms Standard deviation in milliseconds.
mb Size of the garbage collection in megabytes.