corda - NODE_PROPERTIES table in database

Question

What is the purpose of NODE_PROPERTIES table in the database and how do we get this table populated with key value pairs and how do we query? And how do we query data in other NODE tables like NODE_INFOS, NODE_NAMED_IDENTITIES , NODE_INFO_HOSTS? Is there any service level function available in CordaRPCClient to do that? We would like to store some extra properties for each node

Answer 1

The NODE_PROPERTIES table is used for internal purposes to store information that doesn't justify having its own table (currently, whether or not the node was in flow-drain mode when it was last stopped).

Feel free to store additional key-value pairs there, as long as they don't clash with keys used for internal purposes (a clash is unlikely, as we currently use long key-names to store information in this table).

You can get access to the node's database via the node's ServiceHub, which is available inside flows and services. The Flow DB sample shows an example of a service that connects, reads and writes directly to the node's database: https://github.com/corda/samples.

You can also connect directly to the node via JDBC (e.g. from a client or server). The node lists its JDBC database connection string at start-up. You can also set it in the node's configuration file, as shown here: https://docs.corda.net/corda-configuration-file.html#examples.