Better message on error

src/Storages/MergeTree/MergeTreeData.cpp

@@ -1458,6 +1458,16 @@ void MergeTreeData::checkAlterIsPossible(const AlterCommands & commands, const S
         }
         else if (command.isRequireMutationStage(getInMemoryMetadata()))
         {
+            /// Type change for version column is allowed despite it's a part of sorting key
+            if (command.type == AlterCommand::MODIFY_COLUMN && command.column_name == merging_params.version_column)
+            {
+                if (!command.data_type->canBeUsedAsVersion())
+                    throw Exception("Cannot alter version column " + backQuoteIfNeed(command.column_name) +
+                        " to type " + command.data_type->getName() +
+                        " because version column must be of an integer type or of type Date or DateTime"
+                        , ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN);
+                continue;
+            }
             /// This alter will override data on disk. Let's check that it doesn't
             /// modify immutable column.
             if (columns_alter_type_forbidden.count(command.column_name))

tests/queries/0_stateless/01511_alter_version_versioned_collapsing_merge_tree.reference

@@ -0,0 +1,13 @@
+1	1	1	-1
+2	2	2	-1
+CREATE TABLE default.table_with_version\n(\n    `key` UInt64,\n    `value` String,\n    `version` UInt8,\n    `sign` Int8\n)\nENGINE = VersionedCollapsingMergeTree(sign, version)\nORDER BY key\nSETTINGS index_granularity = 8192
+1	1	1	-1
+2	2	2	-1
+CREATE TABLE default.table_with_version\n(\n    `key` UInt64,\n    `value` String,\n    `version` UInt32,\n    `sign` Int8\n)\nENGINE = VersionedCollapsingMergeTree(sign, version)\nORDER BY key\nSETTINGS index_granularity = 8192
+1	1	2	1
+2	2	2	-1
+1	1	2	1
+2	2	2	-1
+3	3	65555	1
+1	1	2	1
+2	2	2	-1

tests/queries/0_stateless/01511_alter_version_versioned_collapsing_merge_tree.sql

@@ -0,0 +1,41 @@
+DROP TABLE IF EXISTS table_with_version;
+
+CREATE TABLE table_with_version
+(
+    key UInt64,
+    value String,
+    version UInt8,
+    sign Int8
+)
+ENGINE VersionedCollapsingMergeTree(sign, version)
+ORDER BY key;
+
+INSERT INTO table_with_version VALUES (1, '1', 1, -1);
+INSERT INTO table_with_version VALUES (2, '2', 2, -1);
+
+SELECT * FROM table_with_version ORDER BY key;
+
+SHOW CREATE TABLE table_with_version;
+
+ALTER TABLE table_with_version MODIFY COLUMN version UInt32;
+
+SELECT * FROM table_with_version ORDER BY key;
+
+SHOW CREATE TABLE table_with_version;
+
+INSERT INTO TABLE table_with_version VALUES(1, '1', 1, 1);
+INSERT INTO TABLE table_with_version VALUES(1, '1', 2, 1);
+
+SELECT * FROM table_with_version FINAL ORDER BY key;
+
+INSERT INTO TABLE table_with_version VALUES(3, '3', 65555, 1);
+
+SELECT * FROM table_with_version FINAL ORDER BY key;
+
+INSERT INTO TABLE table_with_version VALUES(3, '3', 65555, -1);
+
+SELECT * FROM table_with_version FINAL ORDER BY key;
+
+ALTER TABLE table_with_version MODIFY COLUMN version String; --{serverError 524}
+
+DROP TABLE IF EXISTS table_with_version;

tests/queries/0_stateless/01511_alter_version_versioned_collapsing_merge_tree_zookeeper.reference

@@ -0,0 +1,16 @@
+1	1	1	-1
+2	2	2	-1
+CREATE TABLE default.table_with_version_replicated_1\n(\n    `key` UInt64,\n    `value` String,\n    `version` UInt8,\n    `sign` Int8\n)\nENGINE = ReplicatedVersionedCollapsingMergeTree(\'/clickhouse/test_01511/t\', \'1\', sign, version)\nORDER BY key\nSETTINGS index_granularity = 8192
+1	1	1	-1
+2	2	2	-1
+CREATE TABLE default.table_with_version_replicated_1\n(\n    `key` UInt64,\n    `value` String,\n    `version` UInt32,\n    `sign` Int8\n)\nENGINE = ReplicatedVersionedCollapsingMergeTree(\'/clickhouse/test_01511/t\', \'1\', sign, version)\nORDER BY key\nSETTINGS index_granularity = 8192
+1	1	2	1
+2	2	2	-1
+1	1	2	1
+2	2	2	-1
+3	3	65555	1
+1	1	2	1
+2	2	2	-1
+CREATE TABLE default.table_with_version_replicated_2\n(\n    `key` UInt64,\n    `value` String,\n    `version` UInt32,\n    `sign` Int8\n)\nENGINE = ReplicatedVersionedCollapsingMergeTree(\'/clickhouse/test_01511/t\', \'2\', sign, version)\nORDER BY key\nSETTINGS index_granularity = 8192
+1	1	2	1
+2	2	2	-1

tests/queries/0_stateless/01511_alter_version_versioned_collapsing_merge_tree_zookeeper.sql

@@ -0,0 +1,64 @@
+DROP TABLE IF EXISTS table_with_version_replicated_1;
+DROP TABLE IF EXISTS table_with_version_replicated_2;
+
+CREATE TABLE table_with_version_replicated_1
+(
+    key UInt64,
+    value String,
+    version UInt8,
+    sign Int8
+)
+ENGINE ReplicatedVersionedCollapsingMergeTree('/clickhouse/test_01511/t', '1', sign, version)
+ORDER BY key;
+
+CREATE TABLE table_with_version_replicated_2
+(
+    key UInt64,
+    value String,
+    version UInt8,
+    sign Int8
+)
+ENGINE ReplicatedVersionedCollapsingMergeTree('/clickhouse/test_01511/t', '2', sign, version)
+ORDER BY key;
+
+INSERT INTO table_with_version_replicated_1 VALUES (1, '1', 1, -1);
+INSERT INTO table_with_version_replicated_1 VALUES (2, '2', 2, -1);
+
+SELECT * FROM table_with_version_replicated_1 ORDER BY key;
+
+SHOW CREATE TABLE table_with_version_replicated_1;
+
+ALTER TABLE table_with_version_replicated_1 MODIFY COLUMN version UInt32 SETTINGS replication_alter_partitions_sync=2;
+
+SELECT * FROM table_with_version_replicated_1 ORDER BY key;
+
+SHOW CREATE TABLE table_with_version_replicated_1;
+
+INSERT INTO TABLE table_with_version_replicated_1 VALUES(1, '1', 1, 1);
+INSERT INTO TABLE table_with_version_replicated_1 VALUES(1, '1', 2, 1);
+
+SELECT * FROM table_with_version_replicated_1 FINAL ORDER BY key;
+
+INSERT INTO TABLE table_with_version_replicated_1 VALUES(3, '3', 65555, 1);
+
+SELECT * FROM table_with_version_replicated_1 FINAL ORDER BY key;
+
+INSERT INTO TABLE table_with_version_replicated_1 VALUES(3, '3', 65555, -1);
+
+SYSTEM SYNC REPLICA table_with_version_replicated_2;
+
+DETACH TABLE table_with_version_replicated_1;
+DETACH TABLE table_with_version_replicated_2;
+ATTACH TABLE table_with_version_replicated_2;
+ATTACH TABLE table_with_version_replicated_1;
+
+SELECT * FROM table_with_version_replicated_1 FINAL ORDER BY key;
+
+SYSTEM SYNC REPLICA table_with_version_replicated_2;
+
+SHOW CREATE TABLE table_with_version_replicated_2;
+
+SELECT * FROM table_with_version_replicated_2 FINAL ORDER BY key;
+
+DROP TABLE IF EXISTS table_with_version_replicated_1;
+DROP TABLE IF EXISTS table_with_version_replicated_2;