DOC-14763: Product Change- PR #152190 - contention: periodically log resolved contention events (#20522)

* In monitor-and-analyze-transaction-contention.md, added Monitor using logs section.

* In crdb-internal.md, added link to Monitor using logs.

* Incorporated Alyshan’s feedback.

* Incorporated Rich’s feedback.

Author: florence-crl

src/current/v25.4/crdb-internal.md

@@ -1188,6 +1188,8 @@ Contention events are stored in memory. You can control the amount of contention
 
 The `sql.contention.event_store.duration_threshold` [cluster setting]({% link {{ page.version.version }}/cluster-settings.md %}) specifies the minimum contention duration to cause the contention events to be collected into the `crdb_internal.transaction_contention_events` table. The default value is `0`. If contention event collection is overwhelming the CPU or memory you can raise this value to reduce the load.
 
+You can also [monitor transaction contention using logs]({% link {{ page.version.version }}/monitor-and-analyze-transaction-contention.md %}#monitor-using-logs) for a durable history of contention.
+
 {% include {{ page.version.version }}/transaction-contention-events-columns.md %}
 
 #### Transaction contention - example

src/current/v25.4/monitor-and-analyze-transaction-contention.md

@@ -10,6 +10,7 @@ This page shows how to monitor and analyze two types of [contention]({% link {{
 
 - [Console](#monitor-using-console)
 - [Metrics](#monitor-using-metrics)
+- [Logs](#monitor-using-logs)
 - [`crdb_internal` tables](#monitor-using-crdb_internal-tables)
 
 The [Continuous monitoring](#continuous-monitoring) section provides further considerations on identifying when contention occurs in your workload.
@@ -113,6 +114,26 @@ CockroachDB Metric Name | Description | Type | Unit
 
 Correlate these metrics with information from the [Insights]({% link {{ page.version.version }}/ui-insights-page.md %}) and [SQL Activity]({% link {{ page.version.version }}/ui-overview.md %}#sql-activity) pages to identify the affected database.
 
+## Monitor using logs
+
+CockroachDB periodically summarizes resolved contention activity as structured log events on the [`SQL_EXEC` logging channel]({% link {{ page.version.version }}/logging-overview.md %}#logging-channels). Each `aggregated_contention_info` [event]({% link {{ page.version.version }}/eventlog.md %}) reports:
+
+- the waiting statement and transaction fingerprints
+- the blocking transaction fingerprint
+- the contended key (if not redacted)
+- the total wait time for that combination since the previous event
+ 
+[Configure log sinks]({% link {{ page.version.version }}/configure-logs.md %}#configure-log-sinks) to route the `SQL_EXEC` channel to a destination, such as a log file or external collector, for long-term analysis.
+
+These periodic reports complement the in-memory [`crdb_internal.transaction_contention_events`](#transaction_contention_events-table) table by providing a durable view of contention history that persists across [node restarts]({% link {{ page.version.version }}/node-shutdown.md %}) or after contention data expires from the event store. Reports are generated at an interval defined by the cluster setting [`sql.contention.event_store.resolution_interval`](#sql-contention-event_store-resolution_interval).
+
+The structured payload makes it easy to ingest the events into log analytics tools and correlate them with statement fingerprints or [key hotspots]({% link {{ page.version.version }}/understand-hotspots.md %}#row-hotspot). A typical structured log entry looks like the following:
+
+{% include_cached copy-clipboard.html %}
+~~~ json
+{"Timestamp":1756224167482848000,"EventType":"aggregated_contention_info","WaitingStmtFingerprintId":"\\x000000000000007b","WaitingTxnFingerprintId":"\\x00000000000001c8","BlockingTxnFingerprintId":"\\x0000000000000315","ContendedKey":"‹/Table/106/1/8/0›","Duration":300000000}
+~~~
+
 ## Monitor using `crdb_internal` tables
 
 The [`crdb_internal`]({% link {{ page.version.version }}/crdb-internal.md %}) system catalog is a schema that contains information about internal objects, processes, and metrics related to a specific database. `crdb_internal` tables are read-only.
@@ -131,11 +152,11 @@ Setting | Type | Default | Description
 --------|------|---------|-------------
 `sql.contention.event_store.capacity` | byte size | `64 MiB` | the in-memory storage capacity per-node of contention event store
 `sql.contention.event_store.duration_threshold` | duration | `0s` | minimum contention duration to cause the contention events to be collected into crdb_internal.transaction_contention_events. If `0`, always store.
-`sql.contention.event_store.resolution_interval  ` | duration | `30s ` | the interval at which transaction fingerprint ID resolution is performed (set to 0 to disable)
+<a id="sql-contention-event_store-resolution_interval"></a>`sql.contention.event_store.resolution_interval  ` | duration | `30s ` | the interval at which transaction fingerprint ID resolution is performed (set to 0 to disable)
 `sql.contention.record_serialization_conflicts.enabled` | boolean | `true` | enables recording 40001 errors with conflicting txn meta as SERIALIZATION_CONFLICT contention events into crdb_internal.transaction_contention_events
 
 {{site.data.alerts.callout_info}}
-`crdb_internal.transaction_content_events` displays in-memory data, not on-disk data. The data changes over time as new events arrive and old ones are evicted from the cache.
+`crdb_internal.transaction_contention_events` displays in-memory data, not on-disk data. The data changes over time as new events arrive and old ones are evicted from the cache.
 {{site.data.alerts.end}}
 
 The table columns are as follows:
@@ -587,4 +608,4 @@ While the previous analysis process uses the `crdb_internal` tables, the perform
 - Statements page ([CockroachDB Cloud Console]({% link cockroachcloud/statements-page.md %}) or [DB Console]({% link {{ page.version.version }}/ui-statements-page.md %}))
 - Transactions page ([CockroachDB Cloud Console]({% link cockroachcloud/transactions-page.md %}) or [DB Console]({% link {{ page.version.version }}/ui-transactions-page.md %}))
 - Insights page ([CockroachDB Cloud Console]({% link cockroachcloud/insights-page.md %}) or [DB Console]({% link {{ page.version.version }}/ui-insights-page.md %}))
-- [`crdb_internal`]({% link {{ page.version.version }}/crdb-internal.md %})
+- [`crdb_internal`]({% link {{ page.version.version }}/crdb-internal.md %})