server: return garbage percentage per table

This commit adds a new parameter of garbage percentage
per table to the table details endpoint.

Partially addresses #82617

Release note (api change): Add garbage percentage info to Table
Details endpoint.

docs/generated/http/full.md

@@ -5206,6 +5206,7 @@ a table.
 | configure_zone_statement | [string](#cockroach.server.serverpb.TableDetailsResponse-string) |  | configure_zone_statement is the output of "SHOW ZONE CONFIGURATION FOR TABLE" for this table. It is a SQL statement that would re-configure the table's current zone if executed. | [reserved](#support-status) |
 | stats_last_created_at | [google.protobuf.Timestamp](#cockroach.server.serverpb.TableDetailsResponse-google.protobuf.Timestamp) |  | stats_last_created_at is the time at which statistics were last created. | [reserved](#support-status) |
 | has_index_recommendations | [bool](#cockroach.server.serverpb.TableDetailsResponse-bool) |  | has_index_recommendations notifies if the there are index recommendations on this table. | [reserved](#support-status) |
+| garbage_percentage | [float](#cockroach.server.serverpb.TableDetailsResponse-float) |  | garbage_percentage is the percentage of existing MVCC garbage on the table. | [reserved](#support-status) |
 
 
 

pkg/server/admin.go

@@ -897,6 +897,44 @@ func (s *adminServer) tableDetailsHelper(
 		resp.CreateTableStatement = createStmt
 	}
 
+	// MVCC Garbage result.
+	row, cols, err = s.server.sqlServer.internalExecutor.QueryRowExWithCols(
+		ctx, "admin-show-mvcc-garbage-pct", nil,
+		sessiondata.InternalExecutorOverride{User: userName},
+		`WITH
+			range_stats AS (
+				SELECT
+					crdb_internal.range_stats(start_key) AS d
+				FROM
+					crdb_internal.ranges_no_leases
+				WHERE
+					table_id = $1::REGCLASS
+			),
+			aggregated AS (
+				SELECT
+					sum((d->>'live_bytes')::INT8) AS live,
+					sum((d->>'key_bytes')::INT8 + (d->>'val_bytes')::INT8) AS total
+				FROM
+					range_stats
+			)
+			SELECT
+				COALESCE((total - live) / NULLIF(total,0), 0)::FLOAT as garbage_percentage
+			FROM aggregated`,
+		escQualTable,
+	)
+	if err != nil {
+		return nil, err
+	}
+	if row != nil {
+		scanner := makeResultScanner(cols)
+		const garbagePctCol = "garbage_percentage"
+		var garbagePct float32
+		if err := scanner.Scan(row, garbagePctCol, &garbagePct); err != nil {
+			return nil, err
+		}
+		resp.GarbagePercentage = garbagePct
+	}
+
 	// Marshal SHOW STATISTICS result.
 	row, cols, err = s.server.sqlServer.internalExecutor.QueryRowExWithCols(
 		ctx, "admin-show-statistics", nil, /* txn */

pkg/server/serverpb/admin.proto

@@ -218,6 +218,8 @@ message TableDetailsResponse {
   // has_index_recommendations notifies if the there are index recommendations
   // on this table.
   bool has_index_recommendations = 11;
+  // garbage_percentage is the percentage of existing MVCC garbage on the table.
+  float garbage_percentage = 12;
 }
 
 // TableStatsRequest is a request for detailed, computationally expensive