Fixed bug#22680839: DEFAULT IS NOT DETERMINISTIC AND SHOULD NOT BE ALLOWED IN

Benny Wang · Benny Wang · commit cb1f9f68f98a · 2016-03-24T06:47:00.000+01:00
GENERATED COLUMNS

Since it is possible to change the DEFAULT value for a column using ALTER
TABLE, the DEFAULT function may not be considered deterministic.  This can
cause inconsistent results if the DEFAULT function is used in definition of
generated columns after changing the DEFAULT value for a column.  To avoid
this problem, this patch make table rebuild if any column changes the default
value and there is a dependency on DEFAULT function in a generated expression.
diff --git a/mysql-test/suite/gcol/inc/gcol_column_def_options.inc b/mysql-test/suite/gcol/inc/gcol_column_def_options.inc
@@ -578,3 +578,62 @@ SET sql_mode= @sql_mode_save;
 DROP TABLE t1;
 --enable_warnings
 }
+
+
+--echo #
+--echo # Bug#22680839: DEFAULT IS NOT DETERMINISTIC AND SHOULD NOT BE
+--echo #               ALLOWED IN GENERATED COLUMNS
+--echo #
+if ($support_virtual_index)
+{
+CREATE TABLE tzz(a INT DEFAULT 5,
+                 gc1 INT AS (a+DEFAULT(a)) VIRTUAL,
+                 gc2 INT AS (a+DEFAULT(a)) STORED,
+                 KEY k1(gc1));
+INSERT INTO tzz(A) VALUES (1);
+SELECT * FROM tzz;
+SELECT gc1 FROM tzz;
+
+ALTER TABLE tzz MODIFY COLUMN a INT DEFAULT 6;
+SELECT * FROM tzz;
+SELECT gc1 FROM tzz;
+DROP TABLE tzz;
+}
+
+--echo # Test 1: ALTER DEFAULT
+--echo #
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5,
+                b INT AS (1 + DEFAULT(a)) STORED,
+                c INT AS (1 + DEFAULT(a)) VIRTUAL);
+INSERT INTO t1 VALUES ();
+--error ER_ALTER_OPERATION_NOT_SUPPORTED
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7, ALGORITHM = INPLACE;
+--disable_warnings
+# Check how many rows are accessed: >0 = COPY
+--enable_info
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7;
+ALTER TABLE t1 MODIFY COLUMN a INT DEFAULT 8;
+ALTER TABLE t1 CHANGE COLUMN a a DOUBLE DEFAULT 5;
+--disable_info
+DROP TABLE t1;
+
+--echo # Test 2: ALTER DEFAULT + ADD GCOL
+--echo #
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5);
+INSERT INTO t1 VALUES();
+--error ER_ALTER_OPERATION_NOT_SUPPORTED
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+               ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+               ALGORITHM = INPLACE;
+--error ER_ALTER_OPERATION_NOT_SUPPORTED, ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+               ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL,
+               ALGORITHM = INPLACE;
+# Check how many rows are accessed: >0 = COPY
+--enable_info
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+               ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+               ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL;
+--disable_info
+DROP TABLE t1;
+--enable_warnings
diff --git a/mysql-test/suite/gcol/r/gcol_column_def_options_innodb.result b/mysql-test/suite/gcol/r/gcol_column_def_options_innodb.result
@@ -723,6 +723,65 @@ a	b	c
 DELETE FROM t1 where a= 2;
 SET sql_mode= @sql_mode_save;
 DROP TABLE t1;
+#
+# Bug#22680839: DEFAULT IS NOT DETERMINISTIC AND SHOULD NOT BE
+#               ALLOWED IN GENERATED COLUMNS
+#
+CREATE TABLE tzz(a INT DEFAULT 5,
+gc1 INT AS (a+DEFAULT(a)) VIRTUAL,
+gc2 INT AS (a+DEFAULT(a)) STORED,
+KEY k1(gc1));
+INSERT INTO tzz(A) VALUES (1);
+SELECT * FROM tzz;
+a	gc1	gc2
+1	6	6
+SELECT gc1 FROM tzz;
+gc1
+6
+ALTER TABLE tzz MODIFY COLUMN a INT DEFAULT 6;
+SELECT * FROM tzz;
+a	gc1	gc2
+1	7	7
+SELECT gc1 FROM tzz;
+gc1
+7
+DROP TABLE tzz;
+# Test 1: ALTER DEFAULT
+#
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5,
+b INT AS (1 + DEFAULT(a)) STORED,
+c INT AS (1 + DEFAULT(a)) VIRTUAL);
+INSERT INTO t1 VALUES ();
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7, ALGORITHM = INPLACE;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 MODIFY COLUMN a INT DEFAULT 8;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 CHANGE COLUMN a a DOUBLE DEFAULT 5;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+DROP TABLE t1;
+# Test 2: ALTER DEFAULT + ADD GCOL
+#
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5);
+INSERT INTO t1 VALUES();
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+ALGORITHM = INPLACE;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL,
+ALGORITHM = INPLACE;
+Got one of the listed errors
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+DROP TABLE t1;
 DROP VIEW  IF EXISTS v1,v2;
 DROP TABLE IF EXISTS t1,t2,t3;
 DROP PROCEDURE IF EXISTS p1;
diff --git a/mysql-test/suite/gcol/r/gcol_column_def_options_myisam.result b/mysql-test/suite/gcol/r/gcol_column_def_options_myisam.result
@@ -617,6 +617,46 @@ col1	col2	col3	col4	vgc1	sgc1
 1	10	100	111	1000	1000
 2	20	200	222	4000	4000
 DROP TABLE t1;
+#
+# Bug#22680839: DEFAULT IS NOT DETERMINISTIC AND SHOULD NOT BE
+#               ALLOWED IN GENERATED COLUMNS
+#
+# Test 1: ALTER DEFAULT
+#
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5,
+b INT AS (1 + DEFAULT(a)) STORED,
+c INT AS (1 + DEFAULT(a)) VIRTUAL);
+INSERT INTO t1 VALUES ();
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7, ALGORITHM = INPLACE;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 MODIFY COLUMN a INT DEFAULT 8;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 CHANGE COLUMN a a DOUBLE DEFAULT 5;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+DROP TABLE t1;
+# Test 2: ALTER DEFAULT + ADD GCOL
+#
+CREATE TABLE t1(a INT PRIMARY KEY DEFAULT 5);
+INSERT INTO t1 VALUES();
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+ALGORITHM = INPLACE;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL,
+ALGORITHM = INPLACE;
+Got one of the listed errors
+ALTER TABLE t1 ALTER COLUMN a SET DEFAULT 7,
+ADD COLUMN b INT AS (1 + DEFAULT(a)) STORED,
+ADD COLUMN c INT AS (1 + DEFAULT(a)) VIRTUAL;
+affected rows: 1
+info: Records: 1  Duplicates: 0  Warnings: 0
+DROP TABLE t1;
 DROP VIEW  IF EXISTS v1,v2;
 DROP TABLE IF EXISTS t1,t2,t3;
 DROP PROCEDURE IF EXISTS p1;
diff --git a/sql/item.h b/sql/item.h
@@ -2044,6 +2044,16 @@ class Item : public Parse_tree_node
   virtual bool check_gcol_func_processor(uchar *int_arg)
   { return true; }
 
+  /**
+    Check if a generated expression depends on DEFAULT function.
+
+    @param arg ignored
+
+    @returns false if the function is not DEFAULT(), otherwise true.
+  */
+  virtual bool check_gcol_depend_default_processor(uchar *arg)
+  { return false; }
+
   /**
     @brief  update_indexed_column_map
     Update columns map for index.
@@ -4910,6 +4920,9 @@ class Item_default_value : public Item_field
            ((walk & WALK_POSTFIX) && (this->*processor)(args));
   }
 
+  bool check_gcol_depend_default_processor(uchar *arg)
+  { return true; }
+
   Item *transform(Item_transformer transformer, uchar *args);
 };
 
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
@@ -7187,6 +7187,26 @@ static bool is_inplace_alter_impossible(TABLE *table,
   if (!table->s->mysql_version)
     DBUG_RETURN(true);
 
+  /*
+    If default value is changed and the table includes or will include
+    generated columns that depend on the DEFAULT function, we cannot
+    do the operation inplace as indexes or value of stored generated
+    columns might become invalid.
+  */
+  if ((alter_info->flags &
+       (Alter_info::ALTER_CHANGE_COLUMN_DEFAULT |
+        Alter_info::ALTER_CHANGE_COLUMN)) &&
+       table->has_gcol())
+  {
+    for (Field **vfield= table->vfield; *vfield; vfield++)
+    {
+      if ((*vfield)->gcol_info->expr_item->walk(
+           &Item::check_gcol_depend_default_processor,
+           Item::WALK_POSTFIX, NULL))
+        DBUG_RETURN(true);
+    }
+  }
+
   DBUG_RETURN(false);
 }
 
