READ OPERATIONS IN CASSANDRA
In Cassandra read operation performs through different stages to find the data starting from MEMTABLE (RAM) to the end of the data present in SS TABLES(DISK)
COMPONENTS USED TO PASS THE READ QUERY:
▪️ Row cache
▪️ Key cache
▪️ Bloom filters
▪️ Partition summary
▪️ Partition index
▪️ SS Tables
STEPS TO BE FOLLOWED TO READ THE DATA FROM CASSANDRA:
👉 The read request is made from the client.
👉 The data which is requested will be made first checked in MEMTABLE.
👉 If the requested data is found in the MEMTABLE, then it will be read from MEMTABLE and merged with SSTABLE, then it will be sent to the client.
EXECUTION OF READ PATH IN CASSANDRA:
👉 Any server can be queried, which acts as coordinator node in Cassandra.
👉 If we want to access the read data, then we need contact nodes and requested key.
👉 On each node, in data center, the data is pulled from either memtable or sstable and merged.
👉 We can check consistency, while reading the data from Cassandra
Author : Neha Kasanagottu