Version Management

Transactions involving RLV-enabled tables create row-level transaction snapshot versions. A row-level snapshot allows the transaction to commit a version of the table row, rather than a version of the entire table.

Row-level versioning permits concurrent DML changes to the table. (An update to one row may not block another connection's update to another row).

A row-level operation on an RLV-enabled table creates a row-level version.
A table-level operation (such as DDL and table-level DML) on an RLV-enabled table creates a table-level version.
A transaction not involving an RLV-enabled table creates a table-level version.

Note: You must enable row-level transaction snapshot versioning before you can write data to the RLV store.

Open transactions hold versions which are accessible to that transaction. If a transaction is long-running, the server will hold the memory and disk space associated with the RLV and TLV versions until that transaction terminates. Even after a merge, memory for RLV versions will not be freed until the transactions with snapshots referencing these versions are terminated.