[MDEV-19612] Split ALTER related data type specific code in sql_table.cc to Type_handler Created: 2019-05-28  Updated: 2019-05-28  Resolved: 2019-05-28

Status: Closed
Project: MariaDB Server
Component/s: Data types
Fix Version/s: 10.5.0

Type: Task Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Blocks
blocks MDEV-4912 Data type plugin API version 1 Closed

 Description   

Some code in sql_table.cc is not friendly to pluggable data types:

In mysql_prepare_alter_table():

    if ((def->real_field_type() == MYSQL_TYPE_DATE ||
 
         def->real_field_type() == MYSQL_TYPE_NEWDATE ||
 
         def->real_field_type() == MYSQL_TYPE_DATETIME ||
 
         def->real_field_type() == MYSQL_TYPE_DATETIME2) &&
 
         !alter_ctx->datetime_field &&
 
         !(~def->flags & (NO_DEFAULT_VALUE_FLAG | NOT_NULL_FLAG)) &&
 
         thd->variables.sql_mode & MODE_NO_ZERO_DATE)
 
    {
 
        alter_ctx->datetime_field= def;
 
        alter_ctx->error_if_not_empty= TRUE;
 
    }

In mysql_alter_table():

    switch (alter_ctx.datetime_field->real_field_type())
 
    {
 
      case MYSQL_TYPE_DATE:
 
      case MYSQL_TYPE_NEWDATE:
 
        f_val= "0000-00-00";
 
        t_type= MYSQL_TIMESTAMP_DATE;
 
        break;
 
      case MYSQL_TYPE_DATETIME:
 
      case MYSQL_TYPE_DATETIME2:
 
        f_val= "0000-00-00 00:00:00";
 
        t_type= MYSQL_TIMESTAMP_DATETIME;
 
        break;
 
      default:
 
        /* Shouldn't get here. */
 
        DBUG_ASSERT(0);
 
    }

Let's split this code into two new virtual methods in Type_handler:

virtual const Name default_value() const;
 
virtual bool validate_implicit_default_value(THD *thd,
 
                                             const Column_definition &def)
 
                                             const;


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