D.6.35 Changes in release 3.21.0

• New reserved words used: INTERVAL, EXPLAIN, READ, WRITE, BINARY.
• Added ODBC function CHAR(num,...).
• New operator IN. This uses a binary search to find a match.
• New command LOCK TABLES tbl_name [AS alias] {READ|WRITE} ...
• Added --log-update option to mysqld, to get a log suitable for incremental updates.
• New command EXPLAIN SELECT ... to get information about how the optimiser will do the join.
• For easier client code, the client should no longer use FIELD_TYPE_TINY_BLOB, FIELD_TYPE_MEDIUM_BLOB, FIELD_TYPE_LONG_BLOB or FIELD_TYPE_VAR_STRING (as previously returned by mysql_list_fields). You should instead only use FIELD_TYPE_BLOB or FIELD_TYPE_STRING. If you want exact types, you should use the command SHOW FIELDS.
• Added varbinary syntax: 0x###### which can be used as a string (default) or a number.
• FIELD_TYPE_CHAR is renamed to FIELD_TYPE_TINY.
• Changed all fields to C++ classes.
• Removed FORM struct.
• Fields with DEFAULT values no longer need to be NOT NULL.
• New field types:

  ENUM

  A string which can take only a couple of defined values. The value is stored as a 1-3 byte number that is mapped automatically to a string. This is sorted according to string positions!

  SET

  A string which may have one or many string values separated with ','. The string is stored as a 1-, 2-, 3-, 4- or 8-byte number where each bit stands for a specific set member. This is sorted according to the unsigned value of the stored packed number.

• Now all function calculation is done with double or long long. This will provide the full 64-bit range with bit functions and fix some conversions that previously could result in precision losses. One should avoid using unsigned long long columns with full 64-bit range (numbers bigger than 9223372036854775807) because calculations are done with signed long long.
• ORDER BY will now put NULL field values first. GROUP BY will also work with NULL values.
• Full WHERE with expressions.
• New range optimiser that can resolve ranges when some keypart prefix is constant. Example:

  mysql> SELECT * FROM tbl_name
      ->          WHERE key_part_1="customer"
      ->          AND key_part_2>=10 AND key_part_2<=10;
  

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