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WalSenderMain

Short Description

The Write Ahead Log (WAL) sender process is waiting for work.

Additional Information

From the PostgreSQL documentation - Waiting in main loop of WAL sender process.

The WalSender process is seen in systems where replication is enabled. The sender process takes the WAL transactions and send them so the replica where the WalReceiver process write the transactions to WAL segments.

Note that the WalSender process is started in response to a request from a replica, so there can be a number of WalSenders running depending on the number of replicas.

How to reduce this wait

This is an idle wait and is normal to see.

PostgreSQL docs - Wait Events of Type Activity

Percona Blog - Setting up Streaming Replication

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