From 60789584387276975fc5f66935725694e0ce0580 Mon Sep 17 00:00:00 2001
From: Eric Harmeling <eric.harmeling@cockroachlabs.com>
Date: Tue, 6 Sep 2022 15:39:09 -0400
Subject: [PATCH] sql: add created_at to index usage stat telemetry

This commit adds a creation timestamp to the index usage
statistics telemetry.

Fixes https://github.com/cockroachdb/cockroach/issues/84458.

Release justification: low-risk updates to new functionality
Release note(sql change): Added a creation timestamp to index usage statistics
telemetry.
---
 docs/generated/eventlog.md                             |  1 +
 pkg/sql/scheduledlogging/captured_index_usage_stats.go | 10 ++++++++--
 pkg/util/log/eventpb/json_encode_generated.go          | 10 ++++++++++
 pkg/util/log/eventpb/telemetry.proto                   |  1 +
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/docs/generated/eventlog.md b/docs/generated/eventlog.md
index 289f7ba18e21..63769b242f32 100644
--- a/docs/generated/eventlog.md
+++ b/docs/generated/eventlog.md
@@ -2469,6 +2469,7 @@ An event of type `captured_index_usage_stats`
 | `IndexType` |  | no |
 | `IsUnique` |  | no |
 | `IsInverted` |  | no |
+| `CreatedAt` |  | no |
 
 
 #### Common fields
diff --git a/pkg/sql/scheduledlogging/captured_index_usage_stats.go b/pkg/sql/scheduledlogging/captured_index_usage_stats.go
index abaf2836fbcb..a683f5e26b3b 100644
--- a/pkg/sql/scheduledlogging/captured_index_usage_stats.go
+++ b/pkg/sql/scheduledlogging/captured_index_usage_stats.go
@@ -171,7 +171,7 @@ func captureIndexUsageStats(
 
 	// Capture index usage statistics for each database.
 	var ok bool
-	expectedNumDatums := 9
+	expectedNumDatums := 10
 	var allCapturedIndexUsageStats []logpb.EventPayload
 	for _, databaseName := range allDatabaseNames {
 		// Omit index usage statistics on the default databases 'system',
@@ -189,7 +189,8 @@ func captureIndexUsageStats(
 		 ti.is_unique,
 		 ti.is_inverted,
 		 total_reads,
-		 last_read
+		 last_read,
+		 ti.created_at
 		FROM %s.crdb_internal.index_usage_statistics AS us
 		JOIN %s.crdb_internal.table_indexes ti
 		ON us.index_id = ti.index_id
@@ -233,6 +234,10 @@ func captureIndexUsageStats(
 			if row[8] != tree.DNull {
 				lastRead = tree.MustBeDTimestampTZ(row[8]).Time
 			}
+			createdAt := time.Time{}
+			if row[9] != tree.DNull {
+				createdAt = tree.MustBeDTimestamp(row[9]).Time
+			}
 
 			capturedIndexStats := &eventpb.CapturedIndexUsageStats{
 				TableID:        uint32(roachpb.TableID(tableID)),
@@ -245,6 +250,7 @@ func captureIndexUsageStats(
 				IndexType:      string(indexType),
 				IsUnique:       bool(isUnique),
 				IsInverted:     bool(isInverted),
+				CreatedAt:      createdAt.String(),
 			}
 
 			allCapturedIndexUsageStats = append(allCapturedIndexUsageStats, capturedIndexStats)
diff --git a/pkg/util/log/eventpb/json_encode_generated.go b/pkg/util/log/eventpb/json_encode_generated.go
index be1c0b94095b..f020db42fa0a 100644
--- a/pkg/util/log/eventpb/json_encode_generated.go
+++ b/pkg/util/log/eventpb/json_encode_generated.go
@@ -734,6 +734,16 @@ func (m *CapturedIndexUsageStats) AppendJSONFields(printComma bool, b redact.Red
 		b = append(b, "\"IsInverted\":true"...)
 	}
 
+	if m.CreatedAt != "" {
+		if printComma {
+			b = append(b, ',')
+		}
+		printComma = true
+		b = append(b, "\"CreatedAt\":\""...)
+		b = redact.RedactableBytes(jsonbytes.EncodeString([]byte(b), string(m.CreatedAt)))
+		b = append(b, '"')
+	}
+
 	return printComma, b
 }
 
diff --git a/pkg/util/log/eventpb/telemetry.proto b/pkg/util/log/eventpb/telemetry.proto
index 9574ca924b77..91c4118037bf 100644
--- a/pkg/util/log/eventpb/telemetry.proto
+++ b/pkg/util/log/eventpb/telemetry.proto
@@ -171,6 +171,7 @@ message CapturedIndexUsageStats {
   string index_type = 9 [(gogoproto.jsontag) = ",omitempty", (gogoproto.moretags) = "redact:\"nonsensitive\""];
   bool is_unique = 10 [(gogoproto.jsontag) = ",omitempty"];
   bool is_inverted = 11 [(gogoproto.jsontag) = ",omitempty"];
+  string created_at = 12 [(gogoproto.jsontag) = ",omitempty", (gogoproto.moretags) = "redact:\"nonsensitive\""];
 }
 
 // CreateChangefeed is an event for any CREATE CHANGEFEED query that