differences in tables
Certain merge tables were wrongly reported as having incorrect definition:
- Some fields that are 1 byte long (e.g. TINYINT, CHAR(1)), might
be internally casted (in certain cases) to a different type on a
storage engine layer. (affects 4.1 and up)
- If tables in a merge (and a MERGE table itself) had short VARCHAR column (less
than 4 bytes) and at least one (but not all) tables were ALTER'ed (even to an
identical table: ALTER TABLE xxx ENGINE=yyy), table definitions went ouf of
sync. (affects 4.1 only)
This is fixed by relaxing a check for underlying conformance and setting
field type to FIELD_TYPE_STRING in case varchar is shorter than 4
when a table is created.
Using INSERT DELAYED on MERGE tables could lead to table
corruptions.
The manual lists a couple of storage engines, which can be
used with INSERT DELAYED. MERGE is not in this list.
The attempt to try it anyway has not been rejected yet.
This bug was not detected earlier as it can work under
special circumstances. Most notable is low concurrency.
To be safe, this patch rejects any attempt to use INSERT
DELAYED on MERGE tables.
When a merge table is opened compare column and key definition of
underlying tables against column and key definition of merge table.
If any of underlying tables have different column/key definition
refuse to open merge table.
strings
MySQL is setting the flag HA_END_SPACE_KEYS for all the keys that reference
text or varchar columns with collation different than binary.
This was done to handle correctly the situation where a lookup on such a key
may return more than 1 row because of the presence of many rows that differ
only by the amount of trailing space in the table's string column.
Inserting such values however appears to violate the unique checks on
INSERT/UPDATE. Thus that flag must not be set as it will prevent the optimizer
from choosing a faster access method.
This fix removes the setting of the HA_END_SPACE_KEYS flag.
Crash may happen when selecting from a merge table that has underlying
tables with less indexes than in a merge table itself.
If number of keys in merge table is not bigger than requested key number,
return error.
Fixed confusing error message from the storage engine when
it fails to open underlying table. The error message is issued
when a table is _opened_ (not when it is created).
Changed the error reporting (and a crash) when inserting data into a
MERGE table that has no underlying tables or no INSERT_METHOD specified
by reporting that it is read-only.
"alter table from MyISAM to MERGE lost data without errors and warnings"
Add new handlerton flag which prevent user from altering table storage
engine to storage engines which would lose data. Both 'blackhole' and
'merge' are marked with the new flag.
Tests included.
1. Fix index access costs for MERGE tables, set block_size=myisam_block_size/#underlying_tables
instead of 0 which it was before.
2. Make index scans on MERGE table to return records in (key_tuple, merge_table_rowid) order,
instead of just (key_tuple) order. This makes an index scan on MERGE table to be truly a ROR-scan
which is a requirement for index_merge union/intersection.
Problem #1: INSERT...SELECT, Version for 5.0.
Extended the unique table check by a check of lock data.
Merge sub-tables cannot be detected by doing name checks only.
Problem #1: INSERT...SELECT, Version for 4.1.
INSERT ... SELECT with the same table on both sides (hidden
below a MERGE table) does now work by buffering the select result.
The duplicate detection works now after open_and_lock_tables()
on the locks.
I did not find a test case that failed without the change in
sql_update.cc. I made the change anyway as it should in theory
fix a possible MERGE table problem with multi-table update.
The problem was an ab-use of last_rkey_length.
Formerly we saved the packed key length (of the search key)
in this element. But in certain cases it got replaced by
the (packed) result key length.
Now we use a new element of MI_INFO to save the packed key
length of the search key.
After review version.
Added a condition for MERGE tables. These do not have unique
indexes. But every key could be a unique key on the underlying
MyISAM table. So get the maximum key length for MERGE tables
instead of the maximum unique key length. This is used for
buffer allocation in write_record().
myisam_max_extra_sort_file_size is depricated
Ensure that myisam_data_pointer_size is honoured when creating new MyISAM files
Changed default value of myisam_data_pointer_size from 4 to 6 to get rid of 'table-is-full' errors
Changed my_error() to print error messages, which come from
arbitrary registered ranges of error messages. Messages can
be unregistered (and should be at end of the program).
Added registration of handler error messages.
Added a new mi_print_error() macro and a new
mi_report_error() function, which supply error
messages with a table name.
Added calls to mi_print_error() or mi_report_error()
at all places in MyISAM, where table corruption is detected.
Renamed HA_VAR_LENGTH to HA_VAR_LENGTH_PART
Renamed in all files FIELD_TYPE_STRING and FIELD_TYPE_VAR_STRING to MYSQL_TYPE_STRING and MYSQL_TYPE_VAR_STRING to make it easy to catch all possible errors
Added support for VARCHAR KEYS to heap
Removed support for ISAM
Now only long VARCHAR columns are changed to TEXT on demand (not CHAR)
Internal temporary files can now use fixed length tables if the used VARCHAR columns are short
More tests.
Better error messages.
Fixed bug when checking if we updated all needed columns for INSERT.
Give an error if we encounter a wrong float value during parsing.
Don't print DEFAULT for columns without a default value in SHOW CREATE/SHOW FIELDS.
Fixed UPDATE IGNORE when using STRICT mode.
