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fix(metrics): handle NULL stats_reset in pg_stat_wal - #11207
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One thought on the approach here:
Not a blocker, |
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Thanks for the suggestion! I see that I went without the
Happy to use |
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@mnencia What are the next steps? |
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/test feature_type=observability |
Since PostgreSQL 18, pg_stat_wal.stats_reset can be NULL. The metrics exporter scanned it into a non-nullable Go string, so collection failed with "converting NULL to string is unsupported", breaking Prometheus scrapes for otherwise healthy clusters. Coalesce stats_reset to '-infinity' in both pg_stat_wal queries, matching how fillArchiverStatus already handles the nullable last_archived_time and last_failed_time columns in this same file. This keeps StatsReset a plain string and leaves the metric label format unchanged for non-NULL values. Closes cloudnative-pg#9106 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Signed-off-by: Honi Sanders <6538616+HoniSanders@users.noreply.github.com>
Signed-off-by: Niccolò Fei <niccolo.fei@enterprisedb.com>
Since PostgreSQL 18, pg_stat_wal.stats_reset can be NULL. The metrics exporter scanned it into a non-nullable Go string, so metric collection failed with "converting NULL to string is unsupported", breaking Prometheus scrapes on otherwise-healthy clusters. Coalesce stats_reset to '-infinity' in both pg_stat_wal queries in TryGetPgStatWAL, matching how fillArchiverStatus already handles the nullable last_archived_time and last_failed_time columns in this same file. Keeping the column as timestamptz rather than casting to ::text leaves the metric label format unchanged for non-NULL values. Closes #9106 Assisted-by: Claude Signed-off-by: Honi Sanders <6538616+HoniSanders@users.noreply.github.com> Signed-off-by: Niccolò Fei <niccolo.fei@enterprisedb.com> Co-authored-by: Niccolò Fei <niccolo.fei@enterprisedb.com> (cherry picked from commit 953536e)
Since PostgreSQL 18, pg_stat_wal.stats_reset can be NULL. The metrics exporter scanned it into a non-nullable Go string, so metric collection failed with "converting NULL to string is unsupported", breaking Prometheus scrapes on otherwise-healthy clusters. Coalesce stats_reset to '-infinity' in both pg_stat_wal queries in TryGetPgStatWAL, matching how fillArchiverStatus already handles the nullable last_archived_time and last_failed_time columns in this same file. Keeping the column as timestamptz rather than casting to ::text leaves the metric label format unchanged for non-NULL values. Closes #9106 Assisted-by: Claude Signed-off-by: Honi Sanders <6538616+HoniSanders@users.noreply.github.com> Signed-off-by: Niccolò Fei <niccolo.fei@enterprisedb.com> Co-authored-by: Niccolò Fei <niccolo.fei@enterprisedb.com> (cherry picked from commit 953536e)
Since PostgreSQL 18, pg_stat_wal.stats_reset can be NULL. The metrics exporter scanned it into a non-nullable Go string, so metric collection failed with "converting NULL to string is unsupported", breaking Prometheus scrapes on otherwise-healthy clusters. Coalesce stats_reset to '-infinity' in both pg_stat_wal queries in TryGetPgStatWAL, matching how fillArchiverStatus already handles the nullable last_archived_time and last_failed_time columns in this same file. Keeping the column as timestamptz rather than casting to ::text leaves the metric label format unchanged for non-NULL values. Closes #9106 Assisted-by: Claude Signed-off-by: Honi Sanders <6538616+HoniSanders@users.noreply.github.com> Signed-off-by: Niccolò Fei <niccolo.fei@enterprisedb.com> Co-authored-by: Niccolò Fei <niccolo.fei@enterprisedb.com> (cherry picked from commit 953536e)
##### [\`v1.30.1\`](https://github.com/cloudnative-pg/cloudnative-pg/releases/tag/v1.30.1) **Release date:** Sep 23, 2026 ##### Enhancements - Added `restoreAdditionalCommandArgs` to `.barmanObjectStore.data` for in-tree Barman Cloud recoveries, so custom flags are forwarded to `barman-cloud-restore` during recovery. ([#11278](cloudnative-pg/cloudnative-pg#11278)) <!-- 1.29 1.28 --> - Plugin authors no longer need to re-derive whether an empty WAL archive should be treated as an error: the operator now computes the `check_empty_wal_archive` decision once and passes it to CNPG-I plugins on both WAL archiving and restore hooks. ([#11216](cloudnative-pg/cloudnative-pg#11216)) <!-- 1.29 1.28 --> - Allowed setting the `ssl_ecdh_curve` PostgreSQL parameter in `.spec.postgresql.parameters`. It was previously rejected by the validating webhook even though the operator does not manage it. Contributed by [@Jamstah](https://github.com/Jamstah). ([#11308](cloudnative-pg/cloudnative-pg#11308)) <!-- 1.29 1.28 --> - Added support for setting `auth_user` in `spec.pgbouncer.parameters` to override the user PgBouncer uses for its `auth_query` connection, instead of always deriving it from the `authQuerySecret`. Useful with a custom `authQuerySecret` where the role to authenticate as differs from the one implied by the Secret. Contributed by [@jonasbadstuebner](https://github.com/jonasbadstuebner). ([#10899](cloudnative-pg/cloudnative-pg#10899)) <!-- 1.29 1.28 --> - Fixed PgBouncer metrics silently reporting zero when PgBouncer adds or reorders columns: `SHOW STATS` and `SHOW POOLS` results are now matched by column name instead of by position. Contributed by [@AdzerKI](https://github.com/AdzerKI) (`SHOW STATS`). ([#11366](cloudnative-pg/cloudnative-pg#11366), [#11464](cloudnative-pg/cloudnative-pg#11464)) <!-- 1.29 1.28 --> - `cnpg` plugin: - Added a `--dry-run` option to the `backup` command that prints the `Backup` resource that would be created, without creating it. ([#11233](cloudnative-pg/cloudnative-pg#11233)) <!-- 1.29 1.28 --> ##### Security and Supply Chain - Fixed a webhook validation bypass where an absolute extension path with an embedded `..` traversal (e.g. `/a/../../../../etc`) was accepted because only the raw path was checked; such paths still escaped the extension's mount point once resolved at runtime. Affected entries are now resolved and rejected/skipped consistently across admission, the major-upgrade job, and already-persisted Cluster specs. Contributed by [@Anand-240](https://github.com/Anand-240). ([#11210](cloudnative-pg/cloudnative-pg#11210)) <!-- 1.29 1.28 --> - Updated `google.golang.org/grpc` to v1.83.1, fixing [CVE-2026-84304](https://nvd.nist.gov/vuln/detail/CVE-2026-84304) / GHSA-vp52-pcj8-j9qc (gRPC-Go heap memory exhaustion via HTTP/2 DATA frame fragmentation). ([#11394](cloudnative-pg/cloudnative-pg#11394)) <!-- 1.29 1.28 --> ##### Changes - Updated the default PostgreSQL operand image to 18.6-system-trixie. ([#11257](cloudnative-pg/cloudnative-pg#11257)) <!-- 1.29 1.28 --> - Moved the operator's own base image from Debian 12 (bookworm) to Debian 13 (trixie), now that Debian 12 has moved to LTS-only maintenance. ([#11193](cloudnative-pg/cloudnative-pg#11193)) <!-- 1.29 1.28 --> ##### Fixes - Demoted an unreachable old primary immediately during failover, instead of waiting on checkpoint and fast-shutdown attempts that could never complete. Previously, an old primary whose PostgreSQL had become unresponsive was never shut down, so it could never rejoin the cluster as a replica of the new primary. The shutdown is now requested without blocking the reconciler, though demotion can still take up to a minute or more if PostgreSQL keeps ignoring shutdown signals. ([#11347](cloudnative-pg/cloudnative-pg#11347)) <!-- 1.29 1.28 --> - Fixed failover and Pod recreation getting stuck while any instance in the cluster was fenced. A fenced instance kept reporting itself as healthy on its status endpoint even though its Pod was permanently not Ready, which blocked the readiness guard, the primary-election logic, and the Pod-reattachment gate from reacting to an unrelated failure elsewhere in the cluster, leaving it stalled until someone manually removed the fencing. All three now recognize and skip fenced instances. ([#11274](cloudnative-pg/cloudnative-pg#11274)) <!-- 1.29 1.28 --> - Fixed a failover that could stall forever or get silently reverted. While a failover was pending, the reconciler could skip checking whether it was ready to complete, or mistake the pending state for a missing Pod and reset the target primary back to the unhealthy one. It now keeps progressing a pending failover and completes it once the WAL receivers are down, rechecking quorum safety right before promoting in case it changed while waiting. ([#11336](cloudnative-pg/cloudnative-pg#11336)) <!-- 1.29 1.28 --> - Fixed the designated-primary sort in `PostgresqlStatusList` so a tie on LSN no longer sorts it out of order. If the designated primary's Pod later disappeared from the status list, this could have led the operator to promote the wrong standby. ([#11494](cloudnative-pg/cloudnative-pg#11494)) <!-- 1.29 1.28 --> - Gated PostgreSQL startup on the instance manager actually holding the primary `Lease`, closing a window where a restarting or rescheduled primary could start accepting writes before acquiring the lease. Lease acquisition now happens during instance initialization, strictly before PostgreSQL is allowed to start, instead of only later in the reconciliation loop once the instance was already reported ready. ([#11356](cloudnative-pg/cloudnative-pg#11356)) - Bounded the primary lease take-over `Get` call to the lease's `RenewDeadline`, so a call against an unreachable API server now fails fast and retries instead of blocking indefinitely. Left unbounded, the same stalled call could also delay a primary's own lease renewal after a transient API server blip, risking an unwanted takeover by another instance once the lease appeared to expire. ([#11350](cloudnative-pg/cloudnative-pg#11350)) - Stopped abandoning a fast shutdown after 60 seconds. The request carried no explicit timeout, so `pg_ctl` fell back to its own implicit 60-second limit, and the instance manager, being PID 1 in the container, took PostgreSQL down mid-shutdown regardless of a larger configured `stopDelay`. The fast phase now waits for the full `stopDelay` instead. ([#11263](cloudnative-pg/cloudnative-pg#11263)) <!-- 1.29 1.28 --> - Waited for certificate status before refreshing secrets during bootstrap. ([#11450](cloudnative-pg/cloudnative-pg#11450)) <!-- 1.29 1.28 --> - Fixed in-tree Barman Cloud recovery ignoring `wal.maxParallel` and `wal.restoreAdditionalCommandArgs`, fetching WAL one segment at a time instead of using the configured parallelism. ([#11105](cloudnative-pg/cloudnative-pg#11105)) <!-- 1.29 1.28 --> - Honored the `unrecoverable` annotation on pending and terminating instances. ([#11241](cloudnative-pg/cloudnative-pg#11241)) <!-- 1.29 1.28 --> - Honored `Backup.spec.online` when finalizing VolumeSnapshot-based backups, so a cold backup is no longer reported as online in status. ([#11276](cloudnative-pg/cloudnative-pg#11276)) <!-- 1.29 1.28 --> - Set `--no-data-checksums` explicitly when `.spec.postgresql.dataChecksums` is `false` on PostgreSQL 18+, which now enables checksums by default in `initdb`. Contributed by [@evan314159](https://github.com/evan314159). ([#11488](cloudnative-pg/cloudnative-pg#11488)) <!-- 1.29 1.28 --> - Stopped discarding `.spec.inheritedMetadata` labels on PVC reconciliation; they were applied before, and then overwritten by, the operator's own labels. Contributed by [@GellertBabel](https://github.com/GellertBabel). ([#11499](cloudnative-pg/cloudnative-pg#11499)) <!-- 1.29 1.28 --> - Stopped `Pooler` and `DatabaseRole` from recreating their owned resources after being marked for deletion, which could block an external finalizer (e.g. ArgoCD foreground deletion) waiting for those resources to disappear. Contributed by [@mjlshen](https://github.com/mjlshen). ([#11359](cloudnative-pg/cloudnative-pg#11359)) <!-- 1.29 1.28 --> - Handled a `NULL` `stats_reset` value in the `pg_stat_wal` metric, which could occasionally break Prometheus scraping on PostgreSQL 18 clusters. Contributed by [@HoniSanders](https://github.com/HoniSanders). ([#11207](cloudnative-pg/cloudnative-pg#11207)) <!-- 1.29 1.28 --> - Recovered log streaming when a stale non-FIFO file blocked the log pipe. ([#11246](cloudnative-pg/cloudnative-pg#11246)) <!-- 1.29 1.28 --> - Stopped sampling logs of the Pods' processes, so no log lines are silently dropped. ([#11131](cloudnative-pg/cloudnative-pg#11131)) <!-- 1.29 1.28 --> - Stopped caching Helm release Secrets in the operator, which could spike memory usage and crashloop the operator on clusters with large Helm releases installed alongside it. ([#11211](cloudnative-pg/cloudnative-pg#11211)) <!-- 1.29 1.28 --> - Re-ran owned-resource finalizer cleanup after an operator restart, so a namespace deleted while the operator was down doesn't hang in `Terminating` forever. ([#11215](cloudnative-pg/cloudnative-pg#11215)) <!-- 1.29 1.28 --> - Fixed rejoining replicas taking a long time to complete `pg_rewind` when WAL prefetching (`wal.maxParallel > 1`) was enabled. ([#11204](cloudnative-pg/cloudnative-pg#11204)) <!-- 1.29 1.28 --> - Treated a PostgreSQL instance rejecting connections as started up in probes. ([#11152](cloudnative-pg/cloudnative-pg#11152)) <!-- 1.29 1.28 --> - Stopped issuing a redundant PATCH on every reconciliation when a cluster's `pvcTemplate` set `volumeAttributesClass`. Contributed by [@andrew-farries](https://github.com/andrew-farries). ([#11196](cloudnative-pg/cloudnative-pg#11196)) <!-- 1.29 1.28 --> - Stopped halting replication slot reconciliation at the first failing slot. ([#11119](cloudnative-pg/cloudnative-pg#11119)) <!-- 1.29 1.28 --> - During rollouts, compared the running configuration hash, rather than the on-disk one, avoiding unnecessary switchovers. ([#11130](cloudnative-pg/cloudnative-pg#11130)) <!-- 1.29 1.28 --> - Retried `VolumeSnapshot` errors until the deadline, instead of giving up early. ([#11132](cloudnative-pg/cloudnative-pg#11132)) <!-- 1.29 1.28 --> - Symlinked `pg_wal` to the WAL volume during plugin-based recovery, instead of replaying WAL onto the data volume, which could exhaust it on a large point-in-time recovery. ([#11127](cloudnative-pg/cloudnative-pg#11127)) <!-- 1.29 1.28 --> - Corrected grammar in `PhaseUpgradeDelayed` status messages. Contributed by [@Utkarsh-sharma47](https://github.com/Utkarsh-sharma47). ([#11065](cloudnative-pg/cloudnative-pg#11065)) <!-- 1.29 1.28 --> - CloudNativePG Interface (CNPG-I): - Reported the Postgres capabilities of a plugin correctly. ([#11447](cloudnative-pg/cloudnative-pg#11447)) <!-- 1.29 1.28 --> - Prevented the plugin status field from flapping on Cluster reconciliation. Contributed by [@sharifmshaker](https://github.com/sharifmshaker). ([#11386](cloudnative-pg/cloudnative-pg#11386)) <!-- 1.29 1.28 --> - Replaced a finalizer with in-memory cleanup on Service deletion. This avoids namespaces hanging in `Terminating` state when the operator and its plugins run in the same namespace. Contributed by [@maxlengdell](https://github.com/maxlengdell). ([#10940](cloudnative-pg/cloudnative-pg#10940)) <!-- 1.29 --> - `cnpg` plugin: - Used UTC time zone for the default backup name. ([#11329](cloudnative-pg/cloudnative-pg#11329)) <!-- 1.29 1.28 --> - Deleted PVCs before Pods in `cnpg destroy`, avoiding a race that could leave dangling PVCs needing a second invocation to clean up. Contributed by [@daanvinken](https://github.com/daanvinken). ([#10847](cloudnative-pg/cloudnative-pg#10847)) <!-- 1.29 1.28 -->

Since PostgreSQL 18, pg_stat_wal.stats_reset can be NULL. The metrics exporter scanned it into a non-nullable Go string, so metric collection failed with "converting NULL to string is unsupported", breaking Prometheus scrapes on otherwise-healthy clusters.
Coalesce stats_reset to '-infinity' in both pg_stat_wal queries in TryGetPgStatWAL, matching how fillArchiverStatus already handles the nullable last_archived_time and last_failed_time columns in this same file. Keeping the column as timestamptz rather than casting to ::text leaves the metric label format unchanged for non-NULL values.
Closes #9106
Summary
Since PostgreSQL 18,
pg_stat_wal.stats_resetcan beNULL. The metricsexporter scanned it into a non-nullable Go
string, so metric collectionfailed with:
This broke Prometheus scrapes on otherwise-healthy clusters running PostgreSQL 18.
Fix
Coalesce
stats_resetto'-infinity'in bothpg_stat_walqueries inTryGetPgStatWAL. This matches howfillArchiverStatusalready handles thenullable
last_archived_time/last_failed_timecolumns in this same file(
COALESCE(col, '-infinity')into a plain string), soTryGetPgStatWALis nolonger the odd one out scanning a nullable timestamptz directly.
Keeping the column as a
timestamptz(rather than casting to::text) leavesthe metric label format unchanged for non-
NULLvalues and is consistent withthe sibling archiver fields.
Thanks to @mnencia for pointing to the existing pattern.
Testing
stats_resetvalue scanning into the stringfield for both the pre-18 and 18+ query shapes.
go build,go vet, andgo testpass forpkg/management/postgresandpkg/management/postgres/webserver/metricserver.