A rule was introduced by the 5.1 part of the fix for bug 27531 to
prefer filesort over indexed ORDER BY when accessing all of the rows of a
table (because it's faster). This new rule was not accounting for the
presence of a LIMIT clause.
Fixed the condition for this rule so it will prefer filesort over
indexed ORDER BY only if no LIMIT.
- added join cache indication in EXPLAIN (Extra column).
- prefer filesort over full scan over
index for ORDER BY (because it's faster).
- when switching from REF to RANGE because
RANGE uses longer key turn off sort on
the head table only as the resulting
RANGE access is a candidate for join cache
and we don't want to disable it by sorting
on the first table only.
When checking for applicability of join cache
we must disable its usage only if there is no
temp table in use.
When a temp table is used we can use join
cache (and it will not make the result-set
unordered) to fill the temp table. The filesort()
operation is then applied to the data in the temp
table and hence is not affected by join cache
usage.
Fixed by narrowing the condition for disabling
join cache to exclude the case where temp table
is used.
- Use mysql_system_tables.sql to create MySQL system tables in
all places where we create them(mysql_install_db, mysql-test-run-pl
and mysql_fix_privilege_tables.sql)
aliases ignored
When a column reference to a column in JOIN USING is resolved and a new
Item is created for this column the user defined name was lost.
This fix preserves the alias by setting the name of the new Item to the
original alias.
- Make the range-et-al optimizer produce E(#table records after table
condition is applied),
- Make the join optimizer use this value,
- Add "filtered" column to EXPLAIN EXTENDED to show
fraction of records left after table condition is applied
- Adjust test results, add comments
query
Problem:
There was a wrong context assigned to the columns that were added in insert_fields()
when expanding a '*'. When this is done in a prepared statement it causes
fix_fields() to fail to find the table that these columns reference.
Actually the right context is set in setup_natural_join_row_types() called at the
end of setup_tables(). However when executed in a context of a prepared statement
setup_tables() resets the context, but setup_natural_join_row_types() was not
setting it to the correct value assuming it has already done so.
Solution:
The top-most, left-most NATURAL/USING join must be set as a
first_name_resolution_table in context even when operating on prepared statements.
The cause of this bug was a design flaw due to which the list of natural
join columns was incorrectly computed and stored for nested joins that
are not natural joins, but are operands (possibly indirect) of nested joins.
The patch corrects the flaw in a such a way, that the result columns of a
table reference are materialized only if it is a leaf table (that is, only
if it is a view, stored table, or natural/using join).
The cause of the bug was an ASSERT that checked the consistency
of TABLE_SHARE::db and TABLE_LIST::db and failed for I_S tables.
The fix relaxes the requirement for consistency for I_S.
* Provide backwards compatibility extension to name resolution of
coalesced columns. The patch allows such columns to be qualified
with a table (and db) name, as it is in 4.1.
Based on a patch from Monty.
* Adjusted tests accordingly to test both backwards compatible name
resolution of qualified columns, and ANSI-style resolution of
non-qualified columns.
For this, each affected test has two versions - one with qualified
columns, and one without.
- Corrected problem with N-way nested natural joins in PS mode.
- Code cleanup
- More asserts to check consistency of name resolution contexts
- Fixed potential memory leak of name resolution contexts
"Process NATURAL and USING joins according to SQL:2003".
* Some of the main problems fixed by the patch:
- in "select *" queries the * expanded correctly according to
ANSI for arbitrary natural/using joins
- natural/using joins are correctly transformed into JOIN ... ON
for any number/nesting of the joins.
- column references are correctly resolved against natural joins
of any nesting and combined with arbitrary other joins.
* This patch also contains a fix for name resolution of items
inside the ON condition of JOIN ... ON - in this case items must
be resolved only against the JOIN operands. To support such
'local' name resolution, the patch introduces a stack of
name resolution contexts used at parse time.
NOTICE:
- This patch is not complete in the sense that
- there are 2 test cases that still do not pass -
one in join.test, one in select.test. Both are marked
with a comment "TODO: WL#2486".
- it does not include a new test specific for the task
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
Use 0x.... as strings if 'new' mode. (bug 152)
Don't report -max on windows when InnoDB is enabled. (bug 332)
Reset current_linfo; This could cause a hang when doing PURGE LOGS.
Fix for row numbers in EXPLAIN (bug 322)
Fix that USE_FRM works for all table types (bug 97)
Fix for LEFT/RIGHT/MID with multi-byte-character sets (bug 314)
Fix for new bison 1.875
max_insert_delayed_threads and delayed_insert_timeout now works as documented (bug 211)
Don't show port in SHOW PROCESSLIST for system threads
Fix problem with ORDER BY being discarded for some DISTINCT queries (bug 275)
Fixed bug with NATURAL LEFT JOIN, NATURAL RIGHT JOIN and RIGHT JOIN when
using many joined tables (Bug 212)
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)
