TransactionVolume estimates data volume generated by the begin and commit records.
The formula for InboundTransactionVolume is:
InboundTransactionVolume = (MsgSizecommit + MsgSizebegin) * InboundTransactionRate
where:
MsgSizebegin + MsgSizecommit equals 450 bytes per transaction.
InboundTransactionRate is the total number of transactions per time period at the primary database. This includes all transactions—those that update replicated tables and those that do not. One transaction may include one or more modifications to one or more tables.
The formula for OutboundTransactionVolume is:
OutboundTransactionVolume = (MsgSizecommit + MsgSizebegin) * OutboundTransactionRate
where:
MsgSizebegin + MsgSizecommit equals 450 bytes per transaction.
OutboundTransactionRate is the total number of replicated transactions per time period replicated through a particular outbound queue. Each transaction may include one or more modifications to one or more tables.
OutboundTransactionRate depends on:
How many transactions actually update the replicated data
How many of those transactions are replicated through a particular outbound queue
For example, if the InboundTransactionRate is 50 transactions per second, and half of those transactions update replicated tables, and 20 percent of the updates to the replicated tables are replicated through queue 1, the OutboundTransactionRate for queue 1 is 5 transactions per second (50 * 0.5 * 0.2).
Calculating the OutboundTransactionRate can be complicated if transactions contain updates to many different replicated tables with different replication selectivities. In such cases, the InboundTransactionRate provides a convenient upper bound for the OutboundTransactionRate, and you may use it in your formulas instead of the OutboundTransactionRate.
If all transactions in your database are replicated through an outbound queue, then the OutboundTransactionRate is the same as the InboundTransactionRate.
