Fix swapped flushedLsn and receiveStartTli for wal_receiver collector #1198
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| Hi @spantaleev! Do you mind fixing the DCO check please? |
…lector In `pgStatWalReceiverQueryTemplate`, the order of the columns (when `hasFlushedLSN == true`) is: - ... - `receive_start_lsn` - `flushed_lsn` - `receive_start_tli` - ... However, columns were scanned in this order: - ... - `receive_start_lsn` -> `receiveStartLsn` - `receive_start_tli` -> `flushedLsn` (!) - `flushed_lsn` -> `receiveStartTli` (!) - ... This incorrect hydration of variables also manifests as swapped values for the `pg_stat_wal_receiver_flushed_lsn` and `pg_stat_wal_receiver_receive_start_tli` metrics. This seems to be a bug that has existed since the initial implementation: - 2d7e152 - prometheus-community#844 In this patch, I'm: - fixing the `.Scan()`, so that it hydrates variables in the correct order - adjusting the order in which metrics are pushed out to the channel, to follow the order we consume them in (.., `receive_start_lsn`, `flushed_lsn`, `receive_start_tli`, ..) - adjusting the walreceiver tests, to follow the new order (which matches .`Scan()`) - fixing a small identation issue in `pgStatWalReceiverQueryTemplate` Signed-off-by: Slavi Pantaleev <slavi@devture.com>
spantaleev force-pushed the fix-walreceiver-swapped-values branch from b1cc9bc to 024c1fd Compare | I've fixed the sign-off. Sorry for missing that the first time around! |
cristiangreco approved these changes Sep 29, 2025
cristiangreco added a commit that referenced this pull request Sep 29, 2025
* [BUGFIX] Fix swapped `flushedLsn` and `receiveStartTli` for `wal_receiver` collector by @spantaleev in #1198 * [BUGFIX] Fix superfluous semicolon breaking query in `process_idle` by @sysadmind in #1197 and #1201
cristiangreco added a commit that referenced this pull request Sep 29, 2025
* [BUGFIX] Fix swapped `flushedLsn` and `receiveStartTli` for `wal_receiver` collector by @spantaleev in #1198 * [BUGFIX] Fix superfluous semicolon breaking query in `process_idle` by @sysadmind in #1197 and #1201 Signed-off-by: Cristian Greco <cristian@regolo.cc>
sysadmind pushed a commit that referenced this pull request Sep 29, 2025
* [BUGFIX] Fix swapped `flushedLsn` and `receiveStartTli` for `wal_receiver` collector by @spantaleev in #1198 * [BUGFIX] Fix superfluous semicolon breaking query in `process_idle` by @sysadmind in #1197 and #1201 Signed-off-by: Cristian Greco <cristian@regolo.cc>
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In
pgStatWalReceiverQueryTemplate, the order of the columns (whenhasFlushedLSN == true) is:receive_start_lsnflushed_lsnreceive_start_tliHowever, columns were scanned in this order:
receive_start_lsn->receiveStartLsnreceive_start_tli->flushedLsn(!)flushed_lsn->receiveStartTli(!)This incorrect hydration of variables also manifests as swapped values for the
pg_stat_wal_receiver_flushed_lsnandpg_stat_wal_receiver_receive_start_tlimetrics.This seems to be a bug that has existed since the initial implementation:
In this patch, I'm:
fixing the
.Scan(), so that it hydrates variables in the correct orderadjusting the order in which metrics are pushed out to the channel, to follow the order we consume them in (..,
receive_start_lsn,flushed_lsn,receive_start_tli, ..)adjusting the walreceiver tests, to follow the new order (which matches .
Scan())fixing a small identation issue in
pgStatWalReceiverQueryTemplate