October 29, 2006
MySQL Releases version 5.0.27
You may ave noticed The Documentation has not been updated to reflect the version that they are distributing. Curently Version 5.0.27 is now up for download but the changes have not been placed on there website so I can only talk about what changes have been done in verison 5.0.26 which was released on Oct 3, 2006. Just some of the changes I found that are important this go round:
The parser rejected queries that selected from a table twice using a UNION within a subquery. The parser now supports arbitrary subquery, join, and parenthesis operations within EXISTS subqueries. A limitation still exists for scalar subqueries: If the subquery contains UNION, the first SELECT of the UNION cannot be within parentheses. For example, SELECT (SELECT a FROM t1 UNION SELECT b FROM t2) will work, but SELECT ((SELECT a FROM t1) UNION (SELECT b FROM t2)) will not.
EXPLAIN sometimes returned an incorrect select_type for a SELECT from a view, compared to the select_type for the equivalent SELECT from the base table.
Since the current implementation of LOAD DATA FROM MASTER and LOAD TABLE FROM MASTER is very limited, these statements are deprecated in versions 4.1 of MySQL and above. We will introduce a more advanced technique (called “online backup”) in a future version. That technique will have the additional advantage of working with more storage engines.
You may hav noticed they actually gave up on making this feature work correctly in the 5.0 series in favor of mysqlhotcopy.
For MySQL 5.1 and earlier, the recommended alternative solution to using LOAD DATA FROM MASTER or LOAD TABLE FROM MASTERis using mysqldump or mysqlhotcopy. The latter requires Perl and two Perl modules (DBI and DBD:mysql) and works for MyISAM and ARCHIVE tables only. With mysqldump, you can create SQL dumps on the master and pipe (or copy) these to a mysql client on the slave. This has the advantage of working for all storage engines, but can be quite slow, since it works using SELECT.
This statement takes a snapshot of the master and copies it to the slave. It updates the values of MASTER_LOG_FILE and MASTER_LOG_POS so that the slave starts replicating from the correct position. Any table and database exclusion rules specified with the --replicate-*-do-* and --replicate-*-ignore-* options are honored. --replicate-rewrite-db is not taken into account because a user could use this option to set up a non-unique mapping such as --replicate-rewrite-db="db1->db3" and --replicate-rewrite-db="db2->db3", which would confuse the slave when loading tables from the master.
