Add TABLE_TENANT_INFO controller gauge for table-to-tenant mapping

[arunkumarucet]

Summary

• Adds a new TABLE_TENANT_INFO controller gauge emitted by SegmentStatusChecker that encodes the server tenant name as a key segment in the JMX metric name: pinot.controller.tableTenantInfo.<tableNameWithType>.<serverTenant> = 1
• Adds a dedicated JMX exporter rule in controller.yml that extracts table, tableType, tenant, and database as Prometheus labels from this metric
• Enables tenant-scoped aggregation of any existing table-level metric in Prometheus via a group_left(tenant) join — no changes to broker/server metric pipelines required

Motivation

Previously there was no way to aggregate table-scoped metrics (e.g. numDocsScanned, segment counts) by tenant in Prometheus/Grafana without scattered, disruptive changes to add a tenant tag throughout the metrics pipeline. This approach exposes the table→tenant mapping as a standalone info metric that Prometheus can join against.

Aggregate across all tenants:

sum by (tenant) (
  sum by (table) (pinot_server_numDocsScanned_OneMinuteRate{...})
  * on(table) group_left(tenant)
  pinot_controller_tableTenantInfo
)

Filter to a specific tenant (e.g. DefaultTenant):

sum by (tenant) (
  sum by (table) (pinot_server_numDocsScanned_OneMinuteRate{...})
  * on(table) group_left(tenant)
  pinot_controller_tableTenantInfo{tenant="DefaultTenant"}
)

The tenant label can be used in any label matcher (=, !=, =~, !~) wherever PromQL label selectors are supported — in dashboards, alerts, and recording rules.

Implementation

Emission strategy:

• The gauge is written only once per (table, tenant) pair — on first registration or when the tenant changes. It is not re-emitted on every 5-minute SegmentStatusChecker cycle (early-return when tenant is unchanged).
• _tableTenantMap tracks the current tenant per table so stale gauges are removed on: tenant change, null table config, and table removal (nonLeaderCleanup).
• The new gauge is registered before removing the old tenant's gauge on a tenant change, to avoid a scrape-window gap.

JMX metric name:

"org.apache.pinot.common.metrics":type="ControllerMetrics",
  name="pinot.controller.tableTenantInfo.<tableNameWithType>.<serverTenant>"

Prometheus output (via JMX exporter):

pinot_controller_tableTenantInfo_Value{table="airlineStats", tableType="OFFLINE", tenant="DefaultTenant"} 1

Test plan

• SegmentStatusCheckerTest#tableTenantInfoGaugeNamedTenantTest — named server tenant is registered
• SegmentStatusCheckerTest#tableTenantInfoGaugeDefaultTenantFallbackTest — falls back to DefaultTenant when no tenant configured
• SegmentStatusCheckerTest#tableTenantInfoGaugeTenantChangeCleansStaleGaugeTest — stale gauge removed when tenant changes
• SegmentStatusCheckerTest#tableTenantInfoGaugeTableRemovedCleansUpTest — gauge cleaned up via nonLeaderCleanup
• SegmentStatusCheckerTest#tableTenantInfoGaugeRealtimeTableTest — REALTIME table type covered
• Verified locally via batch quickstart: 10 MBeans registered, all value=1, JMX exporter regex validated against no-database, with-database, and REALTIME patterns

[codecov-commenter]

Codecov Report

❌ Patch coverage is 73.68421% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.77%. Comparing base (14bc147) to head (8c6923d).

Files with missing lines	Patch %	Lines
...e/pinot/controller/helix/SegmentStatusChecker.java	72.22%	2 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18823      +/-   ##
============================================
+ Coverage     64.76%   64.77%   +0.01%     
  Complexity     1319     1319              
============================================
  Files          3392     3392              
  Lines        210949   210968      +19     
  Branches      33119    33124       +5     
============================================
+ Hits         136611   136653      +42     
+ Misses        63323    63297      -26     
- Partials      11015    11018       +3     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-21	64.77% <73.68%> (+0.01%)	⬆️
temurin	64.77% <73.68%> (+0.01%)	⬆️
unittests	64.77% <73.68%> (+0.01%)	⬆️
unittests1	56.97% <100.00%> (+0.01%)	⬆️
unittests2	37.19% <73.68%> (+0.01%)	⬆️

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