restore prevValue when confiration is cancelled

Currently, `rawRowsShard` and `rawRowsShards` lives in
`lib/partition.go` file. But these types and the `partition` type are
only loosely coupled. While the `rawRows` logic is scattered across two
files `lib/raw_row.go` and `lib/partition.go`.

This PR moves `rawRowsShard` and `rawRowsShards` and related constants
to `raw_row.go`. This allows to keep related funtionality together and
view raw row types as functionality that is independent from the
`partition` type.

Additionally, the `rawRowsShards` and the `partition` types were
decoupled by using the `func([][]rawRow)` callback.

---------

Signed-off-by: Artem Fetishev <rtm@victoriametrics.com>

app/vmagent/main.go

@@ -462,7 +462,9 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 		return true
 	case "/prometheus/metric-relabel-debug", "/metric-relabel-debug":
 		promscrapeMetricRelabelDebugRequests.Inc()
-		promscrape.WriteMetricRelabelDebug(w, r)
+		rwGlobalRelabelConfigs := remotewrite.GetRemoteWriteRelabelConfigString()
+		rwURLRelabelConfigss := remotewrite.GetURLRelabelConfigString()
+		promscrape.WriteMetricRelabelDebug(w, r, rwGlobalRelabelConfigs, rwURLRelabelConfigss)
 		return true
 	case "/prometheus/target-relabel-debug", "/target-relabel-debug":
 		promscrapeTargetRelabelDebugRequests.Inc()

app/vmagent/remotewrite/relabel.go

@@ -12,6 +12,7 @@ import (
 	"github.com/VictoriaMetrics/metrics"
 	"gopkg.in/yaml.v2"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
@@ -82,6 +83,16 @@ func WriteRelabelConfigData(w io.Writer) {
 	_, _ = w.Write(*p)
 }
 
+// GetRemoteWriteRelabelConfigString returns -remoteWrite.relabelConfig contents in string
+func GetRemoteWriteRelabelConfigString() string {
+	var bb bytesutil.ByteBuffer
+	WriteRelabelConfigData(&bb)
+	if bb.Len() == 0 {
+		return ""
+	}
+	return string(bb.B)
+}
+
 // WriteURLRelabelConfigData writes -remoteWrite.urlRelabelConfig contents to w
 func WriteURLRelabelConfigData(w io.Writer) {
 	p := remoteWriteURLRelabelConfigData.Load()
@@ -108,6 +119,24 @@ func WriteURLRelabelConfigData(w io.Writer) {
 	_, _ = w.Write(d)
 }
 
+// GetURLRelabelConfigString returns -remoteWrite.urlRelabelConfig contents in []string
+func GetURLRelabelConfigString() []string {
+	p := remoteWriteURLRelabelConfigData.Load()
+	if p == nil {
+		return nil
+	}
+	var ss []string
+	for i := range *remoteWriteURLs {
+		cfgData := (*p)[i]
+		var cfgDataBytes []byte
+		if cfgData != nil {
+			cfgDataBytes, _ = yaml.Marshal(cfgData)
+		}
+		ss = append(ss, string(cfgDataBytes))
+	}
+	return ss
+}
+
 func reloadRelabelConfigs() {
 	rcs := allRelabelConfigs.Load()
 	if !rcs.isSet() {

app/vmselect/main.go

@@ -541,7 +541,7 @@ func handleStaticAndSimpleRequests(w http.ResponseWriter, r *http.Request, path
 		return true
 	case "/metric-relabel-debug":
 		promscrapeMetricRelabelDebugRequests.Inc()
-		promscrape.WriteMetricRelabelDebug(w, r)
+		promscrape.WriteMetricRelabelDebug(w, r, "", nil)
 		return true
 	case "/target-relabel-debug":
 		promscrapeTargetRelabelDebugRequests.Inc()

docs/victoriametrics/Articles.md

@@ -114,7 +114,6 @@ See also [case studies](https://docs.victoriametrics.com/victoriametrics/casestu
 * [QCon London 2026: Wrangling Telemetry at Scale, a Guide to Self-Hosted Observability](https://www.infoq.com/news/2026/03/self-hosted-observability/)
 * [How We Made Telemetry Queries 10x Faster: Chunk-Split Caching for Metrics, Logs, and Traces](https://mirastacklabs.ai/blog/chunk-split-caching/)
 * [Claude Code: creating Kubernetes debugging AI Agent for VictoriaMetrics](https://rtfm.co.ua/en/claude-code-creating-kubernetes-debugging-ai-agent-for-victoriametrics/)
-* [OpenTelemetry: OTel Collectors in Kubernetes and VictoriaMetrics Stack integration](https://itnext.io/opentelemetry-otel-collectors-in-kubernetes-and-victoriametrics-stack-integration-d907ed0a15a0)
 
 ## Third-party articles and slides about VictoriaLogs
 

docs/victoriametrics/changelog/CHANGELOG.md

@@ -31,6 +31,7 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 * FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/) and [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/): Improve background discovery performance for [http_sd](https://docs.victoriametrics.com/victoriametrics/sd_configs/#http_sd_configs) discovery. See [#8838](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/8838).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/) and [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/): allow overriding `max_scrape_size` on a per-target basis via the `__max_scrape_size__` label during target relabeling. See [#11188](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11188).
 * FEATURE: [vmstorage](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/) and [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/): add `-maxBackfillAge` command-line flag for limiting ingestion of samples with historical timestamps, for example, when older data has been moved between storage tiers (nvme/hdd, hot/cold). See [#11199](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11199). Thanks to @AshwinRamaniPsg for contribution.
+* FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/): add support for selecting relabel configurations from `-remoteWrite.relabelConfig` and `-remoteWrite.urlRelabelConfig` in the [metrics relabel debug UI](https://docs.victoriametrics.com/victoriametrics/relabeling/#relabel-debugging). See [#9918](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/9918).
 
 * BUGFIX: `vminsert` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): Now drops metadata blocks when communicating with vmstorage nodes over the legacy RPC protocol. To avoid this limitation, upgrade `vmstorage` to a version that supports the new RPC protocol (>= [v1.137.0](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/docs/victoriametrics/changelog/CHANGELOG.md#v11370)). See [#11146](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11146).
 * BUGFIX: [vmbackup](https://docs.victoriametrics.com/victoriametrics/vmbackup/) and [vmbackupmanager](https://docs.victoriametrics.com/victoriametrics/vmbackupmanager/): retry S3 requests failing with `HTTP 429` status code or `TooManyRequests` error code. Previously such requests were not retried, so a short burst of rate limiting would fail the whole backup. See [#11218](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11218). Thanks to @gautamrizwani for contribution.

lib/promrelabel/debug.go

@@ -9,47 +9,48 @@ import (
 )
 
 // WriteMetricRelabelDebug writes /metric-relabel-debug page to w with the corresponding args.
-func WriteMetricRelabelDebug(w io.Writer, targetID, metric, relabelConfigs, format string, err error) {
-	writeRelabelDebug(w, false, targetID, metric, relabelConfigs, format, err)
+func WriteMetricRelabelDebug(w io.Writer, targetID, metric, relabelConfigs string, urlRelabelIndexLength, urlRelabelIndexCurrent int, format string, err error) {
+	writeRelabelDebug(w, false, targetID, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, format, err)
 }
 
 // WriteTargetRelabelDebug writes /target-relabel-debug page to w with the corresponding args.
 func WriteTargetRelabelDebug(w io.Writer, targetID, metric, relabelConfigs, format string, err error) {
-	writeRelabelDebug(w, true, targetID, metric, relabelConfigs, format, err)
+	writeRelabelDebug(w, true, targetID, metric, relabelConfigs, 0, 0, format, err)
 }
 
-func writeRelabelDebug(w io.Writer, isTargetRelabel bool, targetID, metric, relabelConfigs, format string, err error) {
+func writeRelabelDebug(w io.Writer, isTargetRelabel bool, targetID, metric, relabelConfigs string, urlRelabelIndexLength, urlRelabelIndexCurrent int, format string, err error) {
 	if metric == "" {
 		metric = "{}"
 	}
 	targetURL := ""
 	if err != nil {
-		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, err)
+		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err)
 		return
 	}
 
 	metric, err = normalizeInputLabels(metric)
 	if err != nil {
 		err = fmt.Errorf("cannot parse metric: %w", err)
-		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, err)
+		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err)
 		return
 	}
 
 	labels, err := promutil.NewLabelsFromString(metric)
 	if err != nil {
 		err = fmt.Errorf("cannot parse metric: %w", err)
-		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, err)
+		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err)
 		return
 	}
+
 	pcs, err := ParseRelabelConfigsData([]byte(relabelConfigs))
 	if err != nil {
 		err = fmt.Errorf("cannot parse relabel configs: %w", err)
-		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, err)
+		WriteRelabelDebugSteps(w, targetURL, targetID, format, nil, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err)
 		return
 	}
 
 	dss, targetURL := newDebugRelabelSteps(pcs, labels, isTargetRelabel)
-	WriteRelabelDebugSteps(w, targetURL, targetID, format, dss, metric, relabelConfigs, nil)
+	WriteRelabelDebugSteps(w, targetURL, targetID, format, dss, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, nil)
 }
 
 func newDebugRelabelSteps(pcs *ParsedConfigs, labels *promutil.Labels, isTargetRelabel bool) ([]DebugStep, string) {
@@ -140,6 +141,10 @@ func getChangedLabelNames(in, out *promutil.Labels) map[string]struct{} {
 func normalizeInputLabels(metric string) (string, error) {
 	metric = strings.TrimSpace(metric)
 
+	if strings.ContainsRune(metric, '\n') {
+		return metric, fmt.Errorf("only one time series is allowed; got multiple lines")
+	}
+
 	openBrace := strings.Contains(metric, `{`)
 	closeBrace := strings.Contains(metric, `}`)
 

lib/promrelabel/debug.qtpl

@@ -6,37 +6,66 @@
 
 {% stripspace %}
 
-{% func RelabelDebugSteps(targetURL, targetID, format string, dss []DebugStep, metric, relabelConfigs  string, err error) %}
+{% func RelabelDebugSteps(targetURL, targetID, format string, dss []DebugStep, metric, relabelConfigs string, urlRelabelIndexLength, urlRelabelIndexCurrent int, isTargetRelabel bool, err error) %}
   {% if format == "json" %}
-      {%= RelabelDebugStepsJSON(targetURL, targetID, dss, metric, relabelConfigs, err) %}
+      {%= RelabelDebugStepsJSON(targetURL, targetID, dss, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err) %}
   {% else %}
-      {%= RelabelDebugStepsHTML(targetURL, targetID, dss, metric, relabelConfigs, err) %}
+      {%= RelabelDebugStepsHTML(targetURL, targetID, dss, metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, err) %}
   {% endif %}
 {% endfunc %}
 
-{% func RelabelDebugStepsHTML(targetURL, targetID string, dss []DebugStep, metric, relabelConfigs string, err error) %}
+{% func RelabelDebugStepsHTML(targetURL, targetID string, dss []DebugStep, metric, relabelConfigs string, urlRelabelIndexLength, urlRelabelIndexCurrent int, isTargetRelabel bool, err error) %}
 <!DOCTYPE html>
 <html lang="en">
 <head>
     {%= htmlcomponents.CommonHeader() %}
     <title>Metric relabel debug</title>
     <script>
-function submitRelabelDebugForm(e) {
-  var form = e.target;
-  var method = "GET";
-  if (form.elements["relabel_configs"].value.length + form.elements["metric"].value.length > 1000) {
-    method = "POST";
-  }
-  form.method = method;
+function setRelabelDebugFormMethod(form) {
+  form.method = (form.elements["relabel_configs"].value.length + form.elements["metric"].value.length > 1000) ? "POST" : "GET";
 }
+
+function reloadRelabelConfigs(select) {
+  if (!confirm('Reload will discard all modifications to the current configuration. Continue?')) {
+    select.value = select.prevValue;
+    return;
+  }
+  document.getElementById('reload_url_relabel_configs').value = '1';
+  setRelabelDebugFormMethod(select.form);
+  select.form.submit();
+}
+
+function initRelabelConfigsHighlight() {
+  var ta = document.getElementById('relabel-configs-input');
+  var bd = document.getElementById('relabel-configs-backdrop');
+  if (!ta || !bd) return;
+  function escapeHtml(s) {
+    return s.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;');
+  }
+  function highlight(text) {
+    return text.split('\n').map(function(line) {
+      var e = escapeHtml(line);
+      return /^\s*#/.test(line)
+        ? '<span style="color:#999">'+e+'</span>'
+        : '<span style="color:#212529">'+e+'</span>';
+    }).join('\n');
+  }
+  function update() { bd.innerHTML = highlight(ta.value)+'\n'; }
+  ta.addEventListener('input', update);
+  ta.addEventListener('scroll', function() { bd.scrollTop = ta.scrollTop; });
+  update();
+}
+document.addEventListener('DOMContentLoaded', initRelabelConfigsHighlight);
     </script>
 </head>
 <body>
     {%= htmlcomponents.Navbar() %}
     <div class="container-fluid">
-        <a href="https://docs.victoriametrics.com/victoriametrics/relabeling/" target="_blank">Relabeling docs</a>{% space %}
+        <a href="https://docs.victoriametrics.com/victoriametrics/relabeling/" target="_blank">Relabeling Cookbook</a>{% space %}|{% space %}
+        <a href="https://docs.victoriametrics.com/victoriametrics/relabeling/#relabeling-stages" target="_blank">Relabeling Stages</a>
 
         {% if targetID != "" %}
+          {% space %}|{% space %}
           {% if targetURL != "" %}
             <a href="metric-relabel-debug?id={%s targetID %}">Metric relabel debug</a>
           {% else %}
@@ -50,14 +79,14 @@ function submitRelabelDebugForm(e) {
         {% endif %}
 
         <div class="m-3">
-        <form method="POST" onsubmit="submitRelabelDebugForm(event)">
-            {%= relabelDebugFormInputs(metric, relabelConfigs) %}
+        <form method="POST" onsubmit="setRelabelDebugFormMethod(this)">
+            {%= relabelDebugFormInputs(metric, relabelConfigs, urlRelabelIndexLength, urlRelabelIndexCurrent, isTargetRelabel, targetID) %}
             {% if targetID != "" %}
               <input type="hidden" name="id" value="{%s targetID %}" />
             {% endif %}
             <input type="submit" value="Submit" class="btn btn-primary m-1" />
             {% if targetID != "" %}
-                <button type="button" onclick="location.href='?id={%s targetID %}'" class="btn btn-secondary m-1">Reset</button>
+                <button type="button" onclick="location.href='?id={%s targetID %}'" class="btn btn-secondary m-1">Reset All</button>
             {% endif %}
         </form>
         </div>
@@ -72,15 +101,44 @@ function submitRelabelDebugForm(e) {
 </html>
 {% endfunc %}
 
-{% func relabelDebugFormInputs(metric, relabelConfigs string) %}
+{% func relabelDebugFormInputs(metric, relabelConfigs string, urlRelabelIndexLength, urlRelabelIndexCurrent int, isTargetRelabel bool, targetID string) %}
     <div>
-        Relabel configs:<br/>
-        <textarea name="relabel_configs" style="width: 100%; height: 15em; font-family: monospace" class="m-1">{%s relabelConfigs %}</textarea>
-    </div>
+        <!-- show remote write relabel reload only for scrape metric relabel debug and pure relabel debug. discovery debug should not display this section -->
+        {% if !isTargetRelabel %}
+        <div>
+            <div class="m-1">
+                <div class="d-flex align-items-center gap-2 mt-1">
+                    Configs:
+                    {% if urlRelabelIndexLength > 0 %}
+                        <input type="hidden" name="reload_url_relabel_configs" id="reload_url_relabel_configs" value="" />
+                        <select name="url_relabel_configs_index" class="form-select form-select-sm w-auto" onfocus="this.prevValue=this.value" onchange="reloadRelabelConfigs(this)">
+                            {% for i := range urlRelabelIndexLength %}
+                                {% if urlRelabelIndexCurrent == i %}
+                                    <option value="{%d i %}" selected="selected">remote-write-url-{%d i %}</option>
+                                {% else %}
+                                    <option value="{%d i %}">remote-write-url-{%d i %}</option>
+                                {% endif %}
+                            {% endfor %}
+                        </select>
+                    {% endif %}
+                </div>
+            </div>
+        </div>
+        {% else %}
+        Configs:
+        {% endif %}
 
-    <div>
-        Labels:<br/>
-        <textarea name="metric" style="width: 100%; height: 5em; font-family: monospace" class="m-1">{%s metric %}</textarea>
+        <!-- the following text area css was generated with the help of AI to display yaml comments (starting with #) in gray. it could be rewritten in the future -->
+        <div class="m-1" style="position:relative;height:15em;">
+            <div id="relabel-configs-backdrop" style="position:absolute;top:0;left:0;right:0;bottom:0;pointer-events:none;overflow:hidden;font-family:monospace;white-space:pre-wrap;padding:0.375rem 0.75rem;border:1px solid transparent;"></div>
+            <textarea id="relabel-configs-input" name="relabel_configs" class="form-control" style="position:absolute;top:0;left:0;height:100%;font-family:monospace;color:transparent;caret-color:#212529;background:transparent;resize:none;overflow-y:scroll;">
+                {%s relabelConfigs %}
+            </textarea>
+        </div>
+    </div>
+    <div class="mt-2">
+        One Time Series:<br/>
+        <textarea name="metric" style="width: 100%; height: 5em; font-family: monospace" class="m-1" placeholder="up{job=&quot;job_name&quot;,instance=&quot;host:port&quot;}">{%s metric %}</textarea>
     </div>
 {% endfunc %}
 
@@ -153,7 +211,7 @@ function submitRelabelDebugForm(e) {
 {% endif %}
 {% endfunc %}
 
-{% func RelabelDebugStepsJSON(targetURL, targetID string, dss []DebugStep, metric, relabelConfigs string, err error) %}
+{% func RelabelDebugStepsJSON(targetURL, targetID string, dss []DebugStep, metric, relabelConfigs string,  urlRelabelIndexLength, urlRelabelIndexCurrent int, isTargetRelabel bool, err error) %}
 {
     {% if err != nil %}
         "status": "error",

lib/promrelabel/debug_test.go

@@ -10,10 +10,10 @@ import (
 
 // TestWriteRelabelDebugSupportFormats verifies the relabeling debug input, rules and output.
 func TestWriteRelabelDebugSupportFormats(t *testing.T) {
-	f := func(input, rule, expect string) {
+	f := func(input, rules, expect string) {
 		// execute
 		outputWriter := bytes.NewBuffer(nil)
-		writeRelabelDebug(outputWriter, false, "", input, rule, "json", nil)
+		writeRelabelDebug(outputWriter, false, "", input, rules, 0, 0, "json", nil)
 
 		// the response is in JSON with HTML content, extract the `resultingLabels` in JSON and unescape it.
 		resultingLabels := fastjson.GetString(outputWriter.Bytes(), `resultingLabels`)
@@ -41,4 +41,20 @@ func TestWriteRelabelDebugSupportFormats(t *testing.T) {
 	f(`{_name__="metric_name"`, ruleTestParsing, ``)
 	f(`_name__="metric_name}"`, ruleTestParsing, ``)
 	f(`metrics_name}"`, ruleTestParsing, ``)
+
+	// test multiple rules including remote writes
+	// drop all labels and add one in URL relabeling
+	rule1 := `
+- action: labeldrop
+  regex: "drop_me_metrics_relabel"
+`
+	rule2 := `
+- action: labeldrop
+  regex: "drop_me_remote_write_relabel"
+`
+	rule3 := `
+- target_label: add_me_url_relabel
+  replacement: added
+`
+	f(`{__name__="metric_name", drop_me_metrics_relabel="1", drop_me_remote_write_relabel="2"}`, rule1+rule2+rule3, `metric_name{add_me_url_relabel="added"}`)
 }

lib/promscrape/relabel_debug.go

@@ -3,34 +3,103 @@ package promscrape
 import (
 	"fmt"
 	"net/http"
+	"strconv"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutil"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
 )
 
-// WriteMetricRelabelDebug serves requests to /metric-relabel-debug page
-func WriteMetricRelabelDebug(w http.ResponseWriter, r *http.Request) {
+// WriteMetricRelabelDebug serves requests to /metric-relabel-debug page.
+// remotewrite-related relabel configs could be empty as vmsingle doesn't provide remote write feature.
+func WriteMetricRelabelDebug(w http.ResponseWriter, r *http.Request, rwGlobalRelabelConfigs string, rwURLRelabelConfigss []string) {
 	targetID := r.FormValue("id")
 	metric := r.FormValue("metric")
 	relabelConfigs := r.FormValue("relabel_configs")
+
+	// if set, it means user selected another URL from the dropdown and everything will be reloaded.
+	reloadRWURLRelabelConfigs := r.FormValue("reload_url_relabel_configs")
+	rwURLRelabelConfigsIdxStr := r.FormValue("url_relabel_configs_index")
+
 	format := r.FormValue("format")
 	var err error
 
-	if metric == "" && relabelConfigs == "" && targetID != "" {
-		pcs, labels, ok := getMetricRelabelContextByTargetID(targetID)
-		if !ok {
-			err = fmt.Errorf("cannot find target for id=%s", targetID)
-			targetID = ""
-		} else {
-			metric = labels.String()
-			relabelConfigs = pcs.String()
+	// if all per-URL config is empty, it means no per-URL rule is configured.
+	// set it to 0 so the user do not see the options in debug page.
+	rwURLRelabelConfigsLength := 0
+	for _, urlRelabelConfig := range rwURLRelabelConfigss {
+		if urlRelabelConfig != "" {
+			rwURLRelabelConfigsLength = len(rwURLRelabelConfigss)
+			break
 		}
 	}
+
+	rwURLRelabelConfigsIdx, idxErr := strconv.Atoi(rwURLRelabelConfigsIdxStr)
+	if idxErr != nil {
+		rwURLRelabelConfigsIdx = -1
+	}
+
+	// load the initial data with specific remote write URL index (default 0) in 2 cases:
+	// - relabel config is empty. load scrape relabel (if targetID exist) + remote write related relabel (always).
+	// - `reload` is set. load scrape relabel (if targetID exist) + reload remote write related relabel (by the URL index).
+	init := metric == "" && relabelConfigs == "" && reloadRWURLRelabelConfigs == ""
+	reload := reloadRWURLRelabelConfigs != ""
+	if init || reload {
+		// scrape related relabel labels & rules
+		var (
+			pcs    = &promrelabel.ParsedConfigs{} // could be empty
+			labels *promutil.Labels
+			ok     bool
+		)
+		if targetID != "" {
+			pcs, labels, ok = getMetricRelabelContextByTargetID(targetID)
+			if !ok {
+				err = fmt.Errorf("cannot find target for id=%s", targetID)
+				targetID = ""
+			} else {
+				metric = "up"
+				metric += labels.String()
+			}
+		}
+
+		// general relabel rules (remote write)
+		// set the per-URL remote write relabel according to index, any error will fall back the index to 0.
+		rwURLRelabelConfigs := ""
+		if len(rwURLRelabelConfigss) > 0 {
+			// ignore the error if the input is invalid or exceed the length, and fallback to 0.
+			if rwURLRelabelConfigsIdx < 0 || rwURLRelabelConfigsIdx >= len(rwURLRelabelConfigss) {
+				rwURLRelabelConfigsIdx = 0
+			}
+			rwURLRelabelConfigs = rwURLRelabelConfigss[rwURLRelabelConfigsIdx]
+		}
+
+		relabelConfigs = composeRelabelConfigs(pcs.String(), rwGlobalRelabelConfigs, rwURLRelabelConfigs, rwURLRelabelConfigsIdx)
+	}
+
 	if format == "json" {
 		httpserver.EnableCORS(w, r)
 		w.Header().Set("Content-Type", "application/json")
 	}
-	promrelabel.WriteMetricRelabelDebug(w, targetID, metric, relabelConfigs, format, err)
+	promrelabel.WriteMetricRelabelDebug(w, targetID, metric, relabelConfigs, rwURLRelabelConfigsLength, rwURLRelabelConfigsIdx, format, err)
+}
+
+func composeRelabelConfigs(relabelConfigs, rwGlobalRelabelConfigs, rwURLRelabelConfigs string, rwURLIdx int) string {
+	if relabelConfigs != "" {
+		relabelConfigs = "# -promscrape.config .scrape_configs[].metric_relabel_configs\n" + relabelConfigs
+	}
+
+	if rwGlobalRelabelConfigs != "" {
+		relabelConfigs += "\n# -remoteWrite.relabelConfig"
+		relabelConfigs += "\n" + rwGlobalRelabelConfigs
+	}
+
+	if rwURLRelabelConfigs != "" {
+		relabelConfigs += fmt.Sprintf("\n# -remoteWrite.urlRelabelConfig=remote-write-url-%d", rwURLIdx)
+		relabelConfigs += "\n" + rwURLRelabelConfigs
+	}
+
+	return relabelConfigs
 }
 
 // WriteTargetRelabelDebug generates response for /target-relabel-debug page
@@ -48,7 +117,7 @@ func WriteTargetRelabelDebug(w http.ResponseWriter, r *http.Request) {
 			targetID = ""
 		} else {
 			metric = labels.labelsString()
-			relabelConfigs = pcs.String()
+			relabelConfigs = "# -promscrape.config .scrape_configs[].relabel_configs\n" + pcs.String()
 		}
 	}
 	if format == "json" {

lib/storage/partition.go

@@ -11,9 +11,7 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
-	"unsafe"
 
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/atomicutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
@@ -40,14 +38,6 @@ const maxInmemoryParts = 60
 // See appendPartsToMerge tests for details.
 const defaultPartsToMerge = 15
 
-// The number of shards for rawRow entries per partition.
-//
-// Higher number of shards reduces CPU contention and increases the max bandwidth on multi-core systems.
-var rawRowsShardsPerPartition = cgroup.AvailableCPUs()
-
-// The interval for flushing buffered rows into parts, so they become visible to search.
-const pendingRowsFlushInterval = 2 * time.Second
-
 // The interval for guaranteed flush of recently ingested data from memory to on-disk parts, so they survive process crash.
 var dataFlushInterval = 5 * time.Second
 
@@ -66,11 +56,6 @@ func SetDataFlushInterval(d time.Duration) {
 	dataFlushInterval = d
 }
 
-// The maximum number of rawRow items in rawRowsShard.
-//
-// Limit the maximum shard size to 8Mb, since this gives the lowest CPU usage under high ingestion rate.
-const maxRawRowsPerShard = (8 << 20) / int(unsafe.Sizeof(rawRow{}))
-
 // partition represents a partition.
 type partition struct {
 	activeInmemoryMerges atomic.Int64
@@ -480,130 +465,11 @@ func (pt *partition) AddRows(rows []rawRow) {
 		}
 	}
 
-	pt.rawRows.addRows(pt, rows)
+	pt.rawRows.addRows(pt.flushRowssToInmemoryParts, rows)
 }
 
 var isDebug = false
 
-type rawRowsShards struct {
-	flushDeadlineMs atomic.Int64
-
-	shardIdx atomic.Uint32
-
-	// Shards reduce lock contention when adding rows on multi-CPU systems.
-	shards []rawRowsShard
-
-	rowssToFlushLock sync.Mutex
-	rowssToFlush     [][]rawRow
-}
-
-func (rrss *rawRowsShards) init() {
-	rrss.shards = make([]rawRowsShard, rawRowsShardsPerPartition)
-}
-
-func (rrss *rawRowsShards) addRows(pt *partition, rows []rawRow) {
-	shards := rrss.shards
-	shardsLen := uint32(len(shards))
-	for len(rows) > 0 {
-		n := rrss.shardIdx.Add(1)
-		idx := n % shardsLen
-		tailRows, rowsToFlush := shards[idx].addRows(rows)
-		rrss.addRowsToFlush(pt, rowsToFlush)
-		rows = tailRows
-	}
-}
-
-func (rrss *rawRowsShards) addRowsToFlush(pt *partition, rowsToFlush []rawRow) {
-	if len(rowsToFlush) == 0 {
-		return
-	}
-
-	var rowssToMerge [][]rawRow
-
-	rrss.rowssToFlushLock.Lock()
-	if len(rrss.rowssToFlush) == 0 {
-		rrss.updateFlushDeadline()
-	}
-	rrss.rowssToFlush = append(rrss.rowssToFlush, rowsToFlush)
-	if len(rrss.rowssToFlush) >= defaultPartsToMerge {
-		rowssToMerge = rrss.rowssToFlush
-		rrss.rowssToFlush = nil
-	}
-	rrss.rowssToFlushLock.Unlock()
-
-	pt.flushRowssToInmemoryParts(rowssToMerge)
-}
-
-func (rrss *rawRowsShards) Len() int {
-	n := 0
-	for i := range rrss.shards[:] {
-		n += rrss.shards[i].Len()
-	}
-
-	rrss.rowssToFlushLock.Lock()
-	for _, rows := range rrss.rowssToFlush {
-		n += len(rows)
-	}
-	rrss.rowssToFlushLock.Unlock()
-
-	return n
-}
-
-func (rrss *rawRowsShards) updateFlushDeadline() {
-	rrss.flushDeadlineMs.Store(time.Now().Add(pendingRowsFlushInterval).UnixMilli())
-}
-
-type rawRowsShardNopad struct {
-	flushDeadlineMs atomic.Int64
-
-	mu   sync.Mutex
-	rows []rawRow
-}
-
-type rawRowsShard struct {
-	rawRowsShardNopad
-
-	// The padding prevents false sharing
-	_ [atomicutil.CacheLineSize - unsafe.Sizeof(rawRowsShardNopad{})%atomicutil.CacheLineSize]byte
-}
-
-func (rrs *rawRowsShard) Len() int {
-	rrs.mu.Lock()
-	n := len(rrs.rows)
-	rrs.mu.Unlock()
-	return n
-}
-
-func (rrs *rawRowsShard) addRows(rows []rawRow) ([]rawRow, []rawRow) {
-	var rowsToFlush []rawRow
-
-	rrs.mu.Lock()
-	if cap(rrs.rows) == 0 {
-		rrs.rows = newRawRows()
-	}
-	if len(rrs.rows) == 0 {
-		rrs.updateFlushDeadline()
-	}
-	n := copy(rrs.rows[len(rrs.rows):cap(rrs.rows)], rows)
-	rrs.rows = rrs.rows[:len(rrs.rows)+n]
-	rows = rows[n:]
-	if len(rows) > 0 {
-		rowsToFlush = rrs.rows
-		rrs.rows = newRawRows()
-		rrs.updateFlushDeadline()
-		n = copy(rrs.rows[:cap(rrs.rows)], rows)
-		rrs.rows = rrs.rows[:n]
-		rows = rows[n:]
-	}
-	rrs.mu.Unlock()
-
-	return rows, rowsToFlush
-}
-
-func newRawRows() []rawRow {
-	return make([]rawRow, 0, maxRawRowsPerShard)
-}
-
 func (pt *partition) flushRowssToInmemoryParts(rowss [][]rawRow) {
 	if len(rowss) == 0 {
 		return
@@ -1142,7 +1008,7 @@ func (pt *partition) pendingRowsFlusher() {
 }
 
 func (pt *partition) flushPendingRows(isFinal bool) {
-	pt.rawRows.flush(pt, isFinal)
+	pt.rawRows.flush(pt.flushRowssToInmemoryParts, isFinal)
 }
 
 func (pt *partition) flushInmemoryRowsToFiles() {
@@ -1168,66 +1034,6 @@ func (pt *partition) flushInmemoryPartsToFiles(isFinal bool) {
 	}
 }
 
-func (rrss *rawRowsShards) flush(pt *partition, isFinal bool) {
-	var dst [][]rawRow
-
-	currentTimeMs := time.Now().UnixMilli()
-	flushDeadlineMs := rrss.flushDeadlineMs.Load()
-	if isFinal || currentTimeMs >= flushDeadlineMs {
-		rrss.rowssToFlushLock.Lock()
-		dst = rrss.rowssToFlush
-		rrss.rowssToFlush = nil
-		rrss.rowssToFlushLock.Unlock()
-	}
-
-	for i := range rrss.shards {
-		dst = rrss.shards[i].appendRawRowsToFlush(dst, currentTimeMs, isFinal)
-	}
-
-	pt.flushRowssToInmemoryParts(dst)
-}
-
-func (rrs *rawRowsShard) appendRawRowsToFlush(dst [][]rawRow, currentTimeMs int64, isFinal bool) [][]rawRow {
-	flushDeadlineMs := rrs.flushDeadlineMs.Load()
-	if !isFinal && currentTimeMs < flushDeadlineMs {
-		// Fast path - nothing to flush
-		return dst
-	}
-
-	// Slow path - move rrs.rows to dst.
-	rrs.mu.Lock()
-	dst = appendRawRowss(dst, rrs.rows)
-	rrs.rows = rrs.rows[:0]
-	rrs.mu.Unlock()
-
-	return dst
-}
-
-func (rrs *rawRowsShard) updateFlushDeadline() {
-	rrs.flushDeadlineMs.Store(time.Now().Add(pendingRowsFlushInterval).UnixMilli())
-}
-
-func appendRawRowss(dst [][]rawRow, src []rawRow) [][]rawRow {
-	if len(src) == 0 {
-		return dst
-	}
-	if len(dst) == 0 {
-		dst = append(dst, newRawRows())
-	}
-	prows := &dst[len(dst)-1]
-	n := copy((*prows)[len(*prows):cap(*prows)], src)
-	*prows = (*prows)[:len(*prows)+n]
-	src = src[n:]
-	for len(src) > 0 {
-		rows := newRawRows()
-		n := copy(rows[:cap(rows)], src)
-		rows = rows[:len(rows)+n]
-		src = src[n:]
-		dst = append(dst, rows)
-	}
-	return dst
-}
-
 func (pt *partition) mergePartsToFiles(pws []*partWrapper, stopCh <-chan struct{}, concurrencyCh chan struct{}, useSparseCache bool) error {
 	pwsLen := len(pws)
 

lib/storage/raw_row.go

@@ -3,11 +3,29 @@ package storage
 import (
 	"sort"
 	"sync"
+	"sync/atomic"
+	"time"
+	"unsafe"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/atomicutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/decimal"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 )
 
+// The number of shards for rawRow entries.
+//
+// Higher number of shards reduces CPU contention and increases the max bandwidth on multi-core systems.
+var numRawRowsShards = cgroup.AvailableCPUs()
+
+// The interval for flushing buffered rows into parts, so they become visible to search.
+const pendingRowsFlushInterval = 2 * time.Second
+
+// The maximum number of rawRow items in rawRowsShard.
+//
+// Limit the maximum shard size to 8Mb, since this gives the lowest CPU usage under high ingestion rate.
+const maxRawRowsPerShard = (8 << 20) / int(unsafe.Sizeof(rawRow{}))
+
 // rawRow represents raw timeseries row.
 type rawRow struct {
 	// TSID is time series id.
@@ -149,3 +167,182 @@ func putRawRowsMarshaler(rrm *rawRowsMarshaler) {
 }
 
 var rrmPool sync.Pool
+
+type rawRowsShards struct {
+	flushDeadlineMs atomic.Int64
+
+	shardIdx atomic.Uint32
+
+	// Shards reduce lock contention when adding rows on multi-CPU systems.
+	shards []rawRowsShard
+
+	rowssToFlushLock sync.Mutex
+	rowssToFlush     [][]rawRow
+}
+
+func (rrss *rawRowsShards) init() {
+	rrss.shards = make([]rawRowsShard, numRawRowsShards)
+}
+
+func (rrss *rawRowsShards) Len() int {
+	n := 0
+	for i := range rrss.shards[:] {
+		n += rrss.shards[i].Len()
+	}
+
+	rrss.rowssToFlushLock.Lock()
+	for _, rows := range rrss.rowssToFlush {
+		n += len(rows)
+	}
+	rrss.rowssToFlushLock.Unlock()
+
+	return n
+}
+
+func (rrss *rawRowsShards) addRows(flush func([][]rawRow), rows []rawRow) {
+	shards := rrss.shards
+	shardsLen := uint32(len(shards))
+	for len(rows) > 0 {
+		n := rrss.shardIdx.Add(1)
+		idx := n % shardsLen
+		tailRows, rowsToFlush := shards[idx].addRows(rows)
+		rrss.addRowsToFlush(flush, rowsToFlush)
+		rows = tailRows
+	}
+}
+
+func (rrss *rawRowsShards) addRowsToFlush(flush func([][]rawRow), rowsToFlush []rawRow) {
+	if len(rowsToFlush) == 0 {
+		return
+	}
+
+	var rowssToMerge [][]rawRow
+
+	rrss.rowssToFlushLock.Lock()
+	if len(rrss.rowssToFlush) == 0 {
+		rrss.updateFlushDeadline()
+	}
+	rrss.rowssToFlush = append(rrss.rowssToFlush, rowsToFlush)
+	if len(rrss.rowssToFlush) >= defaultPartsToMerge {
+		rowssToMerge = rrss.rowssToFlush
+		rrss.rowssToFlush = nil
+	}
+	rrss.rowssToFlushLock.Unlock()
+
+	flush(rowssToMerge)
+}
+
+func (rrss *rawRowsShards) updateFlushDeadline() {
+	rrss.flushDeadlineMs.Store(time.Now().Add(pendingRowsFlushInterval).UnixMilli())
+}
+
+func (rrss *rawRowsShards) flush(flush func(rrs [][]rawRow), isFinal bool) {
+	var dst [][]rawRow
+
+	currentTimeMs := time.Now().UnixMilli()
+	flushDeadlineMs := rrss.flushDeadlineMs.Load()
+	if isFinal || currentTimeMs >= flushDeadlineMs {
+		rrss.rowssToFlushLock.Lock()
+		dst = rrss.rowssToFlush
+		rrss.rowssToFlush = nil
+		rrss.rowssToFlushLock.Unlock()
+	}
+
+	for i := range rrss.shards {
+		dst = rrss.shards[i].appendRawRowsToFlush(dst, currentTimeMs, isFinal)
+	}
+
+	flush(dst)
+}
+
+type rawRowsShardNopad struct {
+	flushDeadlineMs atomic.Int64
+
+	mu   sync.Mutex
+	rows []rawRow
+}
+
+type rawRowsShard struct {
+	rawRowsShardNopad
+
+	// The padding prevents false sharing
+	_ [atomicutil.CacheLineSize - unsafe.Sizeof(rawRowsShardNopad{})%atomicutil.CacheLineSize]byte
+}
+
+func (rrs *rawRowsShard) Len() int {
+	rrs.mu.Lock()
+	n := len(rrs.rows)
+	rrs.mu.Unlock()
+	return n
+}
+
+func (rrs *rawRowsShard) addRows(rows []rawRow) ([]rawRow, []rawRow) {
+	var rowsToFlush []rawRow
+
+	rrs.mu.Lock()
+	if cap(rrs.rows) == 0 {
+		rrs.rows = newRawRows()
+	}
+	if len(rrs.rows) == 0 {
+		rrs.updateFlushDeadline()
+	}
+	n := copy(rrs.rows[len(rrs.rows):cap(rrs.rows)], rows)
+	rrs.rows = rrs.rows[:len(rrs.rows)+n]
+	rows = rows[n:]
+	if len(rows) > 0 {
+		rowsToFlush = rrs.rows
+		rrs.rows = newRawRows()
+		rrs.updateFlushDeadline()
+		n = copy(rrs.rows[:cap(rrs.rows)], rows)
+		rrs.rows = rrs.rows[:n]
+		rows = rows[n:]
+	}
+	rrs.mu.Unlock()
+
+	return rows, rowsToFlush
+}
+
+func newRawRows() []rawRow {
+	return make([]rawRow, 0, maxRawRowsPerShard)
+}
+
+func (rrs *rawRowsShard) updateFlushDeadline() {
+	rrs.flushDeadlineMs.Store(time.Now().Add(pendingRowsFlushInterval).UnixMilli())
+}
+
+func (rrs *rawRowsShard) appendRawRowsToFlush(dst [][]rawRow, currentTimeMs int64, isFinal bool) [][]rawRow {
+	flushDeadlineMs := rrs.flushDeadlineMs.Load()
+	if !isFinal && currentTimeMs < flushDeadlineMs {
+		// Fast path - nothing to flush
+		return dst
+	}
+
+	// Slow path - move rrs.rows to dst.
+	rrs.mu.Lock()
+	dst = appendRawRowss(dst, rrs.rows)
+	rrs.rows = rrs.rows[:0]
+	rrs.mu.Unlock()
+
+	return dst
+}
+
+func appendRawRowss(dst [][]rawRow, src []rawRow) [][]rawRow {
+	if len(src) == 0 {
+		return dst
+	}
+	if len(dst) == 0 {
+		dst = append(dst, newRawRows())
+	}
+	prows := &dst[len(dst)-1]
+	n := copy((*prows)[len(*prows):cap(*prows)], src)
+	*prows = (*prows)[:len(*prows)+n]
+	src = src[n:]
+	for len(src) > 0 {
+		rows := newRawRows()
+		n := copy(rows[:cap(rows)], src)
+		rows = rows[:len(rows)+n]
+		src = src[n:]
+		dst = append(dst, rows)
+	}
+	return dst
+}