sql,server: provide an approximate creation time for indexes

This change plumbs a timestamp through to the index descriptor when it is
created. The timestamp used is based on the transaction start time. The
timestamp is then plumbed into the `crdb_internal.table_indexes` table and
exposed as a new NULL-able TIMESTAMP column, `created_at`.

Then, lastly, the timestamp is plumbed through to the status server via the
`TableIndexStatsRequest`.

Release note (sql change): The database now records the approximate time when
an index was created it. This information is exposed via a new NULL-able
TIMESTAMP column, `created_at`, on `crdb_internal.table_indexes`.

docs/generated/http/full.md

@@ -4181,6 +4181,7 @@ Response object returned by TableIndexStatsResponse.
 | index_name | [string](#cockroach.server.serverpb.TableIndexStatsResponse-string) |  | index_name is the name of the index. | [reserved](#support-status) |
 | index_type | [string](#cockroach.server.serverpb.TableIndexStatsResponse-string) |  | index_type is the type of the index i.e. primary, secondary. | [reserved](#support-status) |
 | create_statement | [string](#cockroach.server.serverpb.TableIndexStatsResponse-string) |  | create_statement is the SQL statement that would re-create the current index if executed. | [reserved](#support-status) |
+| created_at | [google.protobuf.Timestamp](#cockroach.server.serverpb.TableIndexStatsResponse-google.protobuf.Timestamp) |  | CreatedAt is an approximate timestamp at which the index was created. Note that it may not always be populated. | [reserved](#support-status) |
 
 
 

pkg/ccl/importccl/import_table_creation.go

@@ -34,6 +34,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
 	"github.com/cockroachdb/cockroach/pkg/util/errorutil/unimplemented"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
+	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
 	"github.com/cockroachdb/errors"
 	"github.com/lib/pq/oid"
 )
@@ -168,6 +169,7 @@ func MakeSimpleTableDescriptor(
 		Regions:            makeImportRegionOperator(""),
 		SessionDataStack:   sessiondata.NewStack(&sessiondata.SessionData{}),
 		ClientNoticeSender: &faketreeeval.DummyClientNoticeSender{},
+		TxnTimestamp:       timeutil.Unix(0, walltime),
 		Settings:           st,
 	}
 	affected := make(map[descpb.ID]*tabledesc.Mutable)

pkg/ccl/logictestccl/testdata/logic_test/crdb_internal_tenant

@@ -275,10 +275,10 @@ SELECT * FROM crdb_internal.table_columns WHERE descriptor_name = ''
 ----
 descriptor_id  descriptor_name  column_id  column_name  column_type  nullable  default_expr  hidden
 
-query ITITTBBB colnames
+query ITITTBBBT colnames
 SELECT * FROM crdb_internal.table_indexes WHERE descriptor_name = ''
 ----
-descriptor_id  descriptor_name  index_id  index_name  index_type  is_unique  is_inverted  is_sharded
+descriptor_id  descriptor_name  index_id  index_name  index_type  is_unique  is_inverted  is_sharded  created_at
 
 query ITITTITTB colnames
 SELECT * FROM crdb_internal.index_columns WHERE descriptor_name = ''

pkg/ccl/serverccl/statusccl/tenant_status_test.go

@@ -508,7 +508,7 @@ WHERE
 }
 
 func testTableIndexStats(ctx context.Context, t *testing.T, testHelper *tenantTestHelper) {
-	getTableIndexStats := func(helper *tenantTestHelper, db string) *serverpb.TableIndexStatsResponse {
+	getTableIndexStats := func(t *testing.T, helper *tenantTestHelper, db string) *serverpb.TableIndexStatsResponse {
 		// Get index usage stats using function call.
 		cluster := helper.testCluster()
 		status := cluster.tenantStatusSrv(randomServer)
@@ -520,6 +520,8 @@ func testTableIndexStats(ctx context.Context, t *testing.T, testHelper *tenantTe
 
 	cluster := testHelper.testCluster()
 
+	timePreCreate := timeutil.Now()
+
 	// Create table on a database.
 	cluster.tenantConn(0).Exec(t, `
 CREATE DATABASE test_db1;
@@ -555,21 +557,61 @@ FROM pg_catalog.pg_indexes
 WHERE tablename = 'test' AND indexname = $1`
 
 	// Get index usage stats and assert expected results.
-	resp := getTableIndexStats(testHelper, "test_db1")
-	require.Equal(t, uint64(1), resp.Statistics[0].Statistics.Stats.TotalReadCount)
-	require.True(t, resp.Statistics[0].Statistics.Stats.LastRead.After(timePreRead))
-	indexName := resp.Statistics[0].IndexName
-	createStmt := cluster.tenantConn(0).QueryStr(t, getCreateStmtQuery, indexName)[0][0]
-	print(createStmt)
-	require.Equal(t, resp.Statistics[0].CreateStatement, createStmt)
-
-	resp = getTableIndexStats(testHelper, "test_db2")
-	require.Equal(t, uint64(0), resp.Statistics[0].Statistics.Stats.TotalReadCount)
-	require.Equal(t, resp.Statistics[0].Statistics.Stats.LastRead, time.Time{})
-	indexName = resp.Statistics[0].IndexName
-	cluster.tenantConn(0).Exec(t, `SET DATABASE=test_db2`)
-	createStmt = cluster.tenantConn(0).QueryStr(t, getCreateStmtQuery, indexName)[0][0]
-	require.Equal(t, resp.Statistics[0].CreateStatement, createStmt)
+	requireAfter := func(t *testing.T, a, b *time.Time) {
+		t.Helper()
+		require.NotNil(t, a)
+		require.NotNil(t, b)
+		require.Truef(t, a.After(*b), "%v is not after %v", a, b)
+	}
+	requireBetween := func(t *testing.T, before time.Time, ts *time.Time, after time.Time) {
+		t.Helper()
+		requireAfter(t, ts, &before)
+		requireAfter(t, &after, ts)
+	}
+
+	t.Run("validate read index", func(t *testing.T) {
+		resp := getTableIndexStats(t, testHelper, "test_db1")
+		require.Equal(t, uint64(1), resp.Statistics[0].Statistics.Stats.TotalReadCount)
+		requireAfter(t, &resp.Statistics[0].Statistics.Stats.LastRead, &timePreRead)
+		indexName := resp.Statistics[0].IndexName
+		createStmt := cluster.tenantConn(0).QueryStr(t, getCreateStmtQuery, indexName)[0][0]
+		print(createStmt)
+		require.Equal(t, resp.Statistics[0].CreateStatement, createStmt)
+		requireBetween(t, timePreCreate, resp.Statistics[0].CreatedAt, timePreRead)
+	})
+
+	t.Run("validate unread index", func(t *testing.T) {
+		resp := getTableIndexStats(t, testHelper, "test_db2")
+		require.Equal(t, uint64(0), resp.Statistics[0].Statistics.Stats.TotalReadCount)
+		require.Equal(t, resp.Statistics[0].Statistics.Stats.LastRead, time.Time{})
+		indexName := resp.Statistics[0].IndexName
+		cluster.tenantConn(0).Exec(t, `SET DATABASE=test_db2`)
+		createStmt := cluster.tenantConn(0).QueryStr(t, getCreateStmtQuery, indexName)[0][0]
+		require.Equal(t, resp.Statistics[0].CreateStatement, createStmt)
+		requireBetween(t, timePreCreate, resp.Statistics[0].CreatedAt, timePreRead)
+	})
+
+	// Test that a subsequent index creation has an appropriate timestamp.
+	t.Run("validate CreatedAt for new index", func(t *testing.T) {
+		timeBeforeCreateNewIndex := timeutil.Now()
+		cluster.tenantConn(0).Exec(t, `
+SET DATABASE=test_db2;
+CREATE INDEX idx2 ON test (b, a)`)
+		timeAfterCreateNewIndex := timeutil.Now()
+
+		resp := getTableIndexStats(t, testHelper, "test_db2")
+		var stat serverpb.TableIndexStatsResponse_ExtendedCollectedIndexUsageStatistics
+		var found bool
+		for _, idx := range resp.Statistics {
+			if found = idx.IndexName == "idx2"; found {
+				stat = *idx
+				break
+			}
+		}
+		require.True(t, found)
+		requireBetween(t,
+			timeBeforeCreateNewIndex, stat.CreatedAt, timeAfterCreateNewIndex)
+	})
 }
 
 func ensureExpectedStmtFingerprintExistsInRPCResponse(