From d871da5418ec14cb6231635711598e250fe768b8 Mon Sep 17 00:00:00 2001
From: robot-clickhouse <robot-clickhouse@users.noreply.github.com>
Date: Wed, 13 Nov 2024 16:11:02 +0000
Subject: [PATCH] Backport #71679 to 24.3: Fix LOGICAL_ERROR when doing ALTER
 with empty tuple

---
 src/Functions/FunctionsComparison.h                   |  3 +++
 src/Functions/if.cpp                                  |  3 +++
 .../0_stateless/03268_empty_tuple_update.reference    |  1 +
 .../queries/0_stateless/03268_empty_tuple_update.sql  | 11 +++++++++++
 4 files changed, 18 insertions(+)
 create mode 100644 tests/queries/0_stateless/03268_empty_tuple_update.reference
 create mode 100644 tests/queries/0_stateless/03268_empty_tuple_update.sql

diff --git a/src/Functions/FunctionsComparison.h b/src/Functions/FunctionsComparison.h
index 57aebc11da0..a9e5a0c1524 100644
--- a/src/Functions/FunctionsComparison.h
+++ b/src/Functions/FunctionsComparison.h
@@ -1048,6 +1048,9 @@ private:
             size_t tuple_size,
             size_t input_rows_count) const
     {
+        if (0 == tuple_size)
+            throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Comparison of zero-sized tuples is not implemented");
+
         ColumnsWithTypeAndName less_columns(tuple_size);
         ColumnsWithTypeAndName equal_columns(tuple_size - 1);
         ColumnsWithTypeAndName tmp_columns(2);
diff --git a/src/Functions/if.cpp b/src/Functions/if.cpp
index 4f75042ad8d..120dbe36543 100644
--- a/src/Functions/if.cpp
+++ b/src/Functions/if.cpp
@@ -760,6 +760,9 @@ private:
         temporary_columns[0] = arguments[0];
 
         size_t tuple_size = type1.getElements().size();
+        if (tuple_size == 0)
+            return ColumnTuple::create(input_rows_count);
+
         Columns tuple_columns(tuple_size);
 
         for (size_t i = 0; i < tuple_size; ++i)
diff --git a/tests/queries/0_stateless/03268_empty_tuple_update.reference b/tests/queries/0_stateless/03268_empty_tuple_update.reference
new file mode 100644
index 00000000000..30bc45d7a18
--- /dev/null
+++ b/tests/queries/0_stateless/03268_empty_tuple_update.reference
@@ -0,0 +1 @@
+()	2
diff --git a/tests/queries/0_stateless/03268_empty_tuple_update.sql b/tests/queries/0_stateless/03268_empty_tuple_update.sql
new file mode 100644
index 00000000000..343117719fc
--- /dev/null
+++ b/tests/queries/0_stateless/03268_empty_tuple_update.sql
@@ -0,0 +1,11 @@
+DROP TABLE IF EXISTS t0;
+
+CREATE TABLE t0 (c0 Tuple(), c1 int) ENGINE = Memory();
+
+INSERT INTO t0 VALUES ((), 1);
+
+ALTER TABLE t0 UPDATE c0 = (), c1 = 2 WHERE EXISTS (SELECT 1);
+
+SELECT * FROM t0;
+
+DROP TABLE t0;