From 0595b5c22b98324089633d0d75ad59ebe78ee768 Mon Sep 17 00:00:00 2001
From: Anton Popov <ap@clickhouse.com>
Date: Wed, 13 Apr 2022 21:50:57 +0000
Subject: [PATCH] fix reading of empty arrays in reverse order

---
 .../CompressedReadBufferFromFile.cpp          |  2 +-
 .../02267_empty_arrays_read_reverse.reference |  1 +
 .../02267_empty_arrays_read_reverse.sql       | 22 +++++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 tests/queries/0_stateless/02267_empty_arrays_read_reverse.reference
 create mode 100644 tests/queries/0_stateless/02267_empty_arrays_read_reverse.sql

diff --git a/src/Compression/CompressedReadBufferFromFile.cpp b/src/Compression/CompressedReadBufferFromFile.cpp
index 9efb3c92cde..a959da2c3ae 100644
--- a/src/Compression/CompressedReadBufferFromFile.cpp
+++ b/src/Compression/CompressedReadBufferFromFile.cpp
@@ -62,7 +62,7 @@ void CompressedReadBufferFromFile::seek(size_t offset_in_compressed_file, size_t
 {
     /// Nothing to do if we already at required position
     if (!size_compressed && static_cast<size_t>(file_in.getPosition()) == offset_in_compressed_file && /// correct position in compressed file
-        (offset() == offset_in_decompressed_block /// correct position in buffer or
+        ((!buffer().empty() && offset() == offset_in_decompressed_block)     /// correct position in buffer or
          || nextimpl_working_buffer_offset == offset_in_decompressed_block)) /// we will move our position to correct one
         return;
 
diff --git a/tests/queries/0_stateless/02267_empty_arrays_read_reverse.reference b/tests/queries/0_stateless/02267_empty_arrays_read_reverse.reference
new file mode 100644
index 00000000000..cc0cc5714d9
--- /dev/null
+++ b/tests/queries/0_stateless/02267_empty_arrays_read_reverse.reference
@@ -0,0 +1 @@
+['x']	0	['1','2','3','4','5','6']
diff --git a/tests/queries/0_stateless/02267_empty_arrays_read_reverse.sql b/tests/queries/0_stateless/02267_empty_arrays_read_reverse.sql
new file mode 100644
index 00000000000..7c1cf47c540
--- /dev/null
+++ b/tests/queries/0_stateless/02267_empty_arrays_read_reverse.sql
@@ -0,0 +1,22 @@
+DROP TABLE IF EXISTS t_02267;
+
+CREATE TABLE t_02267
+(
+    a Array(String),
+    b UInt32,
+    c Array(String)
+)
+ENGINE = MergeTree
+ORDER BY b
+SETTINGS index_granularity = 500;
+
+INSERT INTO t_02267 (b, a, c) SELECT 0, ['x'],  ['1','2','3','4','5','6'] FROM numbers(1) ;
+INSERT INTO t_02267 (b, a, c) SELECT 1, [],     ['1','2','3','4','5','6'] FROM numbers(300000);
+
+OPTIMIZE TABLE t_02267 FINAL;
+
+SELECT * FROM t_02267 WHERE hasAll(a, ['x'])
+ORDER BY b DESC
+SETTINGS max_threads=1, max_block_size=1000;
+
+DROP TABLE IF EXISTS t_02267;