'SELECT DISTINCT a,b FROM t1' should not use temp table if there is unique
index (or primary key) on a.
There are a number of other similar cases that can be calculated without the
use of a temp table : multi-part unique indexes, primary keys or using GROUP BY
instead of DISTINCT.
When a GROUP BY/DISTINCT clause contains all key parts of a unique
index, then it is guaranteed that the fields of the clause will be
unique, therefore we can optimize away GROUP BY/DISTINCT altogether.
This optimization has two effects:
* there is no need to create a temporary table to compute the
GROUP/DISTINCT operation (or the temporary table will be smaller if only GROUP
is removed and DISTINCT stays or if DISTINCT is removed and GROUP BY stays)
* this causes the statement in effect to become updatable in Connector/Java
because the result set columns will be direct reference to the primary key of
the table (instead to the temporary table that it currently references).
Implemented a check that will optimize away GROUP BY/DISTINCT for queries like
the above.
Currently it will work only for single non-constant table in the FROM clause.
Added test cases for bug #12625.
sql_select.cc:
Fixed bug #12625.
Fixed invalid removal of constant items from the DISTINCT
list in the function create_distinct_group.
bmove_allign -> bmove_align
Added OLAP function ROLLUP
Split mysql_fix_privilege_tables to a script and a .sql data file
Added new (MEMROOT*) functions to avoid calling current_thd() when creating some common objects.
Added table_alias_charset, for easier --lower-case-table-name handling
Better SQL_MODE handling (Setting complex options also sets sub options)
New (faster) assembler string functions for x86
Added ALL as parameter option for all group functions.
Make join handling uniform. This allows us to use ',', JOIN and INNER JOIN the same way.
Sort NULL last if DESC is used (ANSI SQL 99 requirement)
Added bug fix from 3.23 for AIX 4.3.3 and gcc 3.x
Small change in EXCHANGE output
Propagate open-files-limit from mysqld_safe -> mysqld
Fixed speed bug in GROUP BY
Added quotes around database name in CREATE DATABASE db_name (for binary log)
Check if AND/OR expression can be NULL; Fixed bug in GROUP BY and-or-expression where expression could be NULL
Bug fix for SHOW OPEN TABLES when user didn't have privilege to access all open tables.
Better fix for ALTER TABLE on BDB tables.
added support for quiet
increased line buffer size
client/mysqltest.c
fixed memory leak
added query logging to result file
added error message logging to result file
added enable_query_log/disable_query_log
mysql-test/mysql-test-run.sh
converted tests to use mysqlmanager
Updated test results
Remember UNION for ALTER TABLE
Added test for if we are supporting transactions.
Don't allow REPLACE to replace a row when we have generated an auto_increment key
Fixed bug when using BLOB keys
Fixed bug in SET @variable=user.
