db: respect EnableColumnarBlocks option on recent FMVs

Fix a bug that caused EnableColumnarBlocks to be ignored on recent format major
versions. Later format major versions may require use of columnar blocks, but
not any in use in CockroachDB v25.2.

Author: jbowens

format_major_version.go

@@ -380,7 +380,7 @@ func (d *DB) TableFormat() sstable.TableFormat {
 		if d.opts.Experimental.EnableValueBlocks == nil || !d.opts.Experimental.EnableValueBlocks() {
 			f = sstable.TableFormatPebblev2
 		}
-	case sstable.TableFormatPebblev5:
+	case sstable.TableFormatPebblev5, sstable.TableFormatPebblev6:
 		if d.opts.Experimental.EnableColumnarBlocks == nil || !d.opts.Experimental.EnableColumnarBlocks() {
 			f = sstable.TableFormatPebblev4
 		}

format_major_version_test.go

@@ -239,3 +239,64 @@ func TestFormatMajorVersions_TableFormat(t *testing.T) {
 	require.Panics(t, func() { _ = fmv.MaxTableFormat() })
 	require.Panics(t, func() { _ = fmv.MinTableFormat() })
 }
+
+// TestFormatMajorVersions_ColumnarBlocks ensures that
+// Experimental.EnableColumnarBlocks is respected on recent format major
+// versions.
+func TestFormatMajorVersions_ColumnarBlocks(t *testing.T) {
+	type testCase struct {
+		fmv     FormatMajorVersion
+		colBlks bool
+		want    sstable.TableFormat
+	}
+	testCases := []testCase{
+		{
+			fmv:     FormatTableFormatV6,
+			colBlks: true,
+			want:    sstable.TableFormatPebblev6,
+		},
+		{
+			fmv:     FormatTableFormatV6,
+			colBlks: false,
+			want:    sstable.TableFormatPebblev4,
+		},
+		{
+			fmv:     FormatColumnarBlocks,
+			colBlks: true,
+			want:    sstable.TableFormatPebblev5,
+		},
+		{
+			fmv:     FormatColumnarBlocks,
+			colBlks: false,
+			want:    sstable.TableFormatPebblev4,
+		},
+		{
+			fmv:     FormatFlushableIngestExcises,
+			colBlks: true,
+			want:    sstable.TableFormatPebblev4,
+		},
+		{
+			fmv:     FormatNewest,
+			colBlks: false,
+			want:    sstable.TableFormatPebblev4,
+		},
+		{
+			fmv:     FormatNewest,
+			colBlks: true,
+			want:    sstable.TableFormatPebblev6,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("(%s,%t)", tc.fmv, tc.colBlks), func(t *testing.T) {
+			opts := &Options{
+				FS:                 vfs.NewMem(),
+				FormatMajorVersion: tc.fmv,
+			}
+			opts.Experimental.EnableColumnarBlocks = func() bool { return tc.colBlks }
+			d, err := Open("", opts)
+			require.NoError(t, err)
+			defer func() { _ = d.Close() }()
+			require.Equal(t, tc.want, d.TableFormat())
+		})
+	}
+}

iterator_histories_test.go

@@ -54,7 +54,7 @@ func TestIterHistories(t *testing.T) {
 				},
 				Logger: testLogger{t},
 			}
-
+			opts.Experimental.EnableColumnarBlocks = func() bool { return true }
 			opts.DisableAutomaticCompactions = true
 			opts.EnsureDefaults()
 			opts.WithFSDefaults()

metrics_test.go

@@ -150,6 +150,7 @@ func TestMetrics(t *testing.T) {
 			MaxOpenFiles: 10000,
 		}
 		opts.Experimental.EnableValueBlocks = func() bool { return true }
+		opts.Experimental.EnableColumnarBlocks = func() bool { return true }
 		opts.Levels = append(opts.Levels, LevelOptions{TargetFileSize: 50})
 
 		// Prevent foreground flushes and compactions from triggering asynchronous