Explain low wal_sender_timeout - #6946
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freza
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Aug 20, 2025
| - `max_wal_senders` — Two needed for every peer node. | ||
| - `max_replication_slots` — Two needed for every peer node. | ||
| - `wal_sender_timeout` and `wal_receiver_timeout` — Determines how | ||
| - `wal_sender_timeout` and `wal_receiver_timeout` — The default of one minute is usually sufficient, but large transactions may require longer than this amount of time to process. Since the wal sender must process the full size of the transaction before transmitting it to a waiting replication connection, Postgres can see that as a timeout. If the problem is actually due to a large transaction, raising wal_sender_timeout to a higher value, like 3600 seconds or higher, and reloading the server could solve the problem. Additionally, this setting determines how |
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Would capitalize "WAL". Would be good to give an example of how to change these values on a running node:
ALTER SYSTEM RESET wal_sender_timeout;
ALTER SYSTEM RESET wal_receiver_timeout;
SELECT pg_reload_conf();
But not sure if this is the right place for it -- up to you.
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(To change them persistently I guess you have to change postgres.conf, but commands for change at runtime are a handy trick.)
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(Also I'd say '1h' or '3600s' to stick with actual config syntax, just to avoid confusion.)
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Fixed the capitalization and the value, thank you!
freza
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Aug 20, 2025
nidhibhammar
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Aug 21, 2025
PJMODOS
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Aug 21, 2025
| - `max_wal_senders` — Two needed for every peer node. | ||
| - `max_replication_slots` — Two needed for every peer node. | ||
| - `wal_sender_timeout` and `wal_receiver_timeout` — Determines how | ||
| - `wal_sender_timeout` and `wal_receiver_timeout` — The default of one minute is usually sufficient, but large transactions may require longer than this amount of time to process. Since the WAL sender must process the full size of the transaction before transmitting it to a waiting replication connection, Postgres can see that as a timeout. If the problem is actually due to a large transaction, raising wal_sender_timeout to a higher value, like `3600s` or higher, and reloading the server could solve the problem. Additionally, this setting determines how |
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We should mention that we always use keepalive to handle networking problems regardless of wal_sender_timeout
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