fix block cache logic for table with no compression

table/table.go

@@ -595,6 +595,11 @@ func (t *Table) block(idx int, useCache bool) (*block, error) {
 			"corrupted or the table options are incorrectly set")
 	}
 
+	if useCache && t.opt.BlockCache != nil && t.opt.Compression == options.None && !t.shouldDecrypt() {
+		// make a copy for caching later
+		blk.data = y.Copy(blk.data)
+	}
+
 	// Read checksum and store it
 	readPos -= blk.chkLen
 	blk.checksum = blk.data[readPos : readPos+blk.chkLen]

table/table_test.go

@@ -32,6 +32,7 @@ import (
 	"github.com/cespare/xxhash/v2"
 	"github.com/stretchr/testify/require"
 
+	"github.com/dgraph-io/badger/v4/fb"
 	"github.com/dgraph-io/badger/v4/options"
 	"github.com/dgraph-io/badger/v4/y"
 	"github.com/dgraph-io/ristretto"
@@ -85,6 +86,20 @@ func buildTable(t *testing.T, keyValues [][]string, opts Options) *Table {
 	return tbl
 }
 
+func TestTableCacheNoCompression(t *testing.T) {
+	opts := getTestTableOptions()
+	opts.Compression = options.None
+	opts.BlockCache, _ = ristretto.NewCache(&cacheConfig)
+
+	table := buildTestTable(t, "key", 1000, opts)
+	blockIdx := 0
+	var ko fb.BlockOffset
+	y.AssertTrue(table.offsets(&ko, blockIdx))
+	expected := ko.Len()
+	blk, _ := table.block(blockIdx, true)
+	require.Equal(t, int(expected), cap(blk.data), "incorrect cached block size")
+}
+
 func TestTableIterator(t *testing.T) {
 	for _, n := range []int{99, 100, 101} {
 		t.Run(fmt.Sprintf("n=%d", n), func(t *testing.T) {