Log-based method of synchronization options v7

walTxSetCreationInterval

When using the log-based method of synchronization replication, the walTxSetCreationInterval option controls the time interval between creations of the transaction sets. This time interval affects the size of the transaction set (that is, the batch size). The default setting results in creating a transaction set every 5,000 milliseconds (5 seconds), assuming changes to the publication tables to be replicated are available.

Adjust this value based on the workload, that is, the transaction per minute (TPM) rate on the target publication tables.

If the TPM rate is on a higher end, set the walTxSetCreationInterval option to a relatively low value.

If the TPM rate is on a lower end, set the option to a higher value. Doing so ensures that a transaction set is large enough to allow an average batch size in the range of 100 to 500 transactions.

walTxSetCreationInterval=n The default value is 5000, in milliseconds.

walStreamQueueLimit

The walStreamQueueLimit option defines the upper limit for the number of WAL entries that can be held in the queue pending for processing at a point in time. Once the queue becomes full, the WAL stream receiver blocks additions until space becomes available in the queue as transaction entries are popped out of the queue for processing.

A value of 0 indicates there is no upper limit. Too high a setting can result in Java heap space out-of-memory errors. See Setting heap memory size for the publication and subscription servers for information on adjusting the Java heap memory size.

walStreamQueueLimit=n

The default value is 10000.

pendingTxSetThreshold

The pendingTxSetThreshold option defines the upper threshold limit for the number of pending transaction sets that, when reached, causes the extraction of transaction data from the WAL stream and its parsing to be put on hold until the pending transactions are processed.

This threshold is to avoid a situation in which the data is continuously pushed over the WAL stream channel but isn't being processed and applied due to some failure or lack of scheduling of the synchronization process. This can result in a Java heap space out-of-heap memory error. See Setting heap memory size for the publication and subscription servers for information on adjusting the Java heap memory size.

pendingTxSetThreshold=n

The default value is 10.