app/vmselect: log calls to /api/v1/admin/tsdb/delete_series

The log message will display when deletion API was called, how many series
it deleted and what params were used. This should help identifying events
of metrics deletion.

Example:
```
2026-06-12T13:02:28.006Z        info    VictoriaMetrics/app/vmselect/prometheus/prometheus.go:529       /api/v1/admin/tsdb/delete_series has been called for "[{__name__=\"vm_http_request_errors_total\"}]". Deleted 0 series.
```

Signed-off-by: hagen1778 <roman@victoriametrics.com>

app/vmselect/prometheus/prometheus.go

@@ -28,6 +28,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httputil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/querytracer"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
@@ -525,6 +526,7 @@ func DeleteHandler(startTime time.Time, r *http.Request) error {
 	if deletedCount > 0 {
 		promql.ResetRollupResultCache()
 	}
+	logger.Infof("/api/v1/admin/tsdb/delete_series has been called for %q. Deleted %d series.", sq.FiltersString(), deletedCount)
 	return nil
 }
 

docs/victoriametrics/changelog/CHANGELOG.md

@@ -26,6 +26,9 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 
 ## tip
 
+* FEATURE: [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/) and `vmselect` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): log calls to [/api/v1/admin/tsdb/delete_series](https://docs.victoriametrics.com/victoriametrics/url-examples/#apiv1admintsdbdelete_series) API handler. This should help to identify events of metrics deletion from the database. 
+
+
 * BUGFIX: [stream aggregation](https://docs.victoriametrics.com/victoriametrics/stream-aggregation/): fix issue with producing aggregated samples with identical timestamps between flushes. See PR [#10808](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/10808) for details.
 
 ## [v1.145.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.145.0)

lib/storage/search.go

@@ -468,15 +468,21 @@ func (tf *TagFilter) Unmarshal(src []byte) ([]byte, error) {
 	return src, nil
 }
 
-// String returns string representation of the search query.
+// String returns string representation of the search query: tag filters and time range.
 func (sq *SearchQuery) String() string {
+	start := TimestampToHumanReadableFormat(sq.MinTimestamp)
+	end := TimestampToHumanReadableFormat(sq.MaxTimestamp)
+	a := sq.FiltersString()
+	return fmt.Sprintf("filters=%s, timeRange=[%s..%s]", a, start, end)
+}
+
+// FiltersString returns string representation of the tag filters.
+func (sq *SearchQuery) FiltersString() []string {
 	a := make([]string, len(sq.TagFilterss))
 	for i, tfs := range sq.TagFilterss {
 		a[i] = tagFiltersToString(tfs)
 	}
-	start := TimestampToHumanReadableFormat(sq.MinTimestamp)
-	end := TimestampToHumanReadableFormat(sq.MaxTimestamp)
-	return fmt.Sprintf("filters=%s, timeRange=[%s..%s]", a, start, end)
+	return a
 }
 
 func tagFiltersToString(tfs []TagFilter) string {