Viraj Jasani created PHOENIX-7375:
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Summary: CQSI connection initialization from SYSTEM.CATALOG
regionserver does not require RPC calls to system tables
Key: PHOENIX-7375
URL: https://issues.apache.org/jira/browse/PHOENIX-7375
Project: Phoenix
Issue Type: Improvement
Affects Versions: 5.2.0
Reporter: Viraj Jasani
In order to execute any query at the server side, Phoenix client requires
creating CQSI (ConnectionQueryServicesImpl) connection, which internally
initiates and maintains long lasting connection against HBase server. CQSI
connection is unique per JDBC url used to initiate the connection. Once
created, CQSI connections are cached per 24 hr (by default) for every unique
JDBC url provided.
When client initiates CQSI connection, the connection initialization also
attempts to execute some metadata queries to ensure that the system tables like
SYSTEM.CATALOG exist and the client version is compatible against the server
version. For this, CQSI#init makes RPC calls against MetaDataEndpointImpl
coproc.
This operation is valid for every CQSI connection initiated for every unique
JDBC url by every client. However, when server hosting SYSTEM.CATALOG initiates
CQSI connection, it means that SYSTEM.CATALOG and other system tables already
exist. Moreover, client/server version compatibility check is not required
because the connection is being created from the same server that is hosting
SYSTEM.CATALOG.
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