SET TRANSACTION sets the transaction priority, access mode, “as of” timestamp, and isolation level. These are applied after you the transaction and before executing the first statement that manipulates a database.
Cockroach Labs recommends leaving the transaction priority at the default setting in almost all cases. Changing the transaction priority to HIGH in particular can lead to difficult-to-debug interactions with other transactions executing on the system.
If you are setting a transaction priority to avoid or , or to , it is usually a sign that you need to update your and/or review the data access patterns of your workload.
Synopsis
Required privileges
No are required to set the transaction priority. However, privileges are required for each statement within a transaction.Parameters
Examples
Set isolation level
You can set the transaction isolation level to or . If not specified, transactions use the value of the current session’s variable.Set priority
This example assumes you’re using .
Use the AS OF SYSTEM TIME option
You can execute the transaction using the database contents “as of” a specified time in the past.
Set the default transaction priority for a session
To set the default transaction priority for all transactions in a session, use thedefault_transaction_priority . For example:
transaction_priority is a read-only that cannot be set directly.