Backport #70127 to 24.9: Fix wrong result with skipping index

src/Storages/MergeTree/MergeTreeIndexSet.cpp

@@ -100,7 +100,10 @@ void MergeTreeIndexGranuleSet::deserializeBinary(ReadBuffer & istr, MergeTreeInd
     size_t rows_to_read = field_rows.safeGet<size_t>();
 
     if (rows_to_read == 0)
+    {
+        block.clear();
         return;
+    }
 
     size_t num_columns = block.columns();
 

tests/queries/0_stateless/03246_skipping_index_70108.reference

@@ -0,0 +1,2 @@
+22
+22

tests/queries/0_stateless/03246_skipping_index_70108.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+$CLICKHOUSE_LOCAL -m "
+    CREATE TABLE t
+    (
+        c0 UInt64,
+        c1 String,
+        INDEX c1_idx c1 TYPE set(666) GRANULARITY 1
+    )
+    ENGINE = MergeTree
+    ORDER BY c0;
+    INSERT INTO t SELECT * FROM file('$CURDIR/data_i70108/repro.tsv.zstd');
+
+SELECT count() FROM t WHERE c1 = 'dedenk1d4q' SETTINGS use_skip_indexes=1;
+SELECT count() FROM t WHERE c1 = 'dedenk1d4q' SETTINGS use_skip_indexes=0;
+"