Using the Advanced Replication parameter bulletin board
solidDB Advanced Replication includes a method for storing parameters on a bulletin board (a memory area) so that the parameter values can be used by other transactions.
There are four types of parameters that can be stored on the parameter bulletin board.
▪ Transaction properties (persistent transaction parameters) that are used for giving a transaction some properties (that describe the transaction), when the transaction is created in the replica database, see Assigning properties to a replicated transaction.
▪ Persistent, catalog-level sync parameters that are used for describing the catalog where the transaction is being executed.
To define a parameter that has a per-catalog scope, you use SET SYNC PARAMETER statement. This statement specifies a parameter that can be read by any transaction (by using the GET_PARAM() function) that executes within that catalog. Each transaction in that catalog can also alter the value of the parameter, but those updated values are only seen within the current transaction. Subsequent transactions do not see the updated values; subsequent transactions only see the original values.
Depending on the type of parameter, there is a different way to specify the parameter and a different mechanism for when and how the parameter is added to the parameter bulletin board. However, the mechanism for reading the parameters from the bulletin board is the same for all types of parameter.
solidDB Advanced Replication also defines a number of system parameters, see Advanced Replication: Bulletin board parameters. System parameters are something that the server knows about and can act upon (for example, by terminating a transaction). The generic catalog-scope parameters are something the application-level Intelligent Transactions must know about. They do not affect the behavior of the server.
System parameters are merely parameters that use names that are reserved by the system. System parameters are visible on the bulletin board, just like any other parameters. Your transaction can read and write system parameters just as it can read and write other parameters.