The primary data access pattern is by row key. No design-time way to specify row keys exists because to HBase they are simply byte arrays. When designing for optimal read performance , it is important to first understand the read path.
The read request is made by a client.
HBase identifies the files that store the rows.
The block index in each file identifies the block in which the row is found.
HBase performs a scan to fetch all the key/value pairs for the request.
A copy is stored in the block cache in memory before a row is returned to the client. Block cache stores the data in ...