MDEV-9519: Data corruption will happen on the Galera cluster size change

If we have a 2+ node cluster which is replicating from an async master
and the binlog_format is set to STATEMENT and multi-row inserts are executed
on a table with an auto_increment column such that values are automatically
generated by MySQL, then the server node generates wrong auto_increment
values, which are different from what was generated on the async master.

In the title of the MDEV-9519 it was proposed to ban start slave on a Galera
if master binlog_format = statement and wsrep_auto_increment_control = 1,
but the problem can be solved without such a restriction.

The causes and fixes:

1. We need to improve processing of changing the auto-increment values
after changing the cluster size.

2. If wsrep auto_increment_control switched on during operation of
the node, then we should immediately update the auto_increment_increment
and auto_increment_offset global variables, without waiting of the next
invocation of the wsrep_view_handler_cb() callback. In the current version
these variables retain its initial values if wsrep_auto_increment_control
is switched on during operation of the node, which leads to inconsistent
results on the different nodes in some scenarios.

3. If wsrep auto_increment_control switched off during operation of the node,
then we must return the original values of the auto_increment_increment and
auto_increment_offset global variables, as the user has set. To make this
possible, we need to add a "shadow copies" of these variables (which stores
the latest values set by the user).

https://jira.mariadb.org/browse/MDEV-9519

1 files changed, 45 insertions, 0 deletions

diff --git a/sql/field.h b/sql/field.h
index 1d01dc72290..422a223ed87 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -1495,6 +1495,17 @@ public:
   /* Hash value */
   virtual void hash(ulong *nr, ulong *nr2);
 
+  /**
+    Get the upper limit of the MySQL integral and floating-point type.
+
+    @return maximum allowed value for the field
+  */
+  virtual ulonglong get_max_int_value() const
+  {
+    DBUG_ASSERT(false);
+    return 0ULL;
+  }
+
 /**
   Checks whether a string field is part of write_set.
 
@@ -2116,6 +2127,10 @@ public:
     *to= *from;
     return from + 1;
   }
+  virtual ulonglong get_max_int_value() const
+  {
+    return unsigned_flag ? 0xFFULL : 0x7FULL;
+  }
 };
 
 
@@ -2160,6 +2175,10 @@ public:
   virtual const uchar *unpack(uchar* to, const uchar *from,
                               const uchar *from_end, uint param_data)
   { return unpack_int16(to, from, from_end); }
+  virtual ulonglong get_max_int_value() const
+  {
+    return unsigned_flag ? 0xFFFFULL : 0x7FFFULL;
+  }
 };
 
 class Field_medium :public Field_int
@@ -2195,6 +2214,10 @@ public:
   {
     return Field::pack(to, from, max_length);
   }
+  virtual ulonglong get_max_int_value() const
+  {
+    return unsigned_flag ? 0xFFFFFFULL : 0x7FFFFFULL;
+  }
 };
 
 
@@ -2244,6 +2267,10 @@ public:
   {
     return unpack_int32(to, from, from_end);
   }
+  virtual ulonglong get_max_int_value() const
+  {
+    return unsigned_flag ? 0xFFFFFFFFULL : 0x7FFFFFFFULL;
+  }
 };
 
 
@@ -2298,6 +2325,10 @@ public:
   }
   void set_max();
   bool is_max();
+  virtual ulonglong get_max_int_value() const
+  {
+    return unsigned_flag ? 0xFFFFFFFFFFFFFFFFULL : 0x7FFFFFFFFFFFFFFFULL;
+  }
 };
 
 
@@ -2380,6 +2411,13 @@ public:
   uint32 pack_length() const { return sizeof(float); }
   uint row_pack_length() const { return pack_length(); }
   void sql_type(String &str) const;
+  virtual ulonglong get_max_int_value() const
+  {
+    /*
+      We use the maximum as per IEEE754-2008 standard, 2^24
+    */
+    return 0x1000000ULL;
+  }
 private:
   int save_field_metadata(uchar *first_byte);
 };
@@ -2433,6 +2471,13 @@ public:
   uint32 pack_length() const { return sizeof(double); }
   uint row_pack_length() const { return pack_length(); }
   void sql_type(String &str) const;
+  virtual ulonglong get_max_int_value() const
+  {
+    /*
+      We use the maximum as per IEEE754-2008 standard, 2^53
+    */
+    return 0x20000000000000ULL;
+  }
 private:
   int save_field_metadata(uchar *first_byte);
 };