Problem:
HASH indexes on VARCHAR columns with binary collations did not ignore trailing spaces from strings before comparisons. This could result in duplicate records being successfully inserted into a MEMORY table with unique key constraints.
As a direct consequence of the above, internal MEMORY tables used for GROUP BY calculation in testcases for bug #27643 contained duplicate rows which resulted in duplicate key errors when converting those temporary tables to MyISAM. Additionally, that error was incorrectly converted to the 'table is full' error.
Solution:
- ignore trailing spaces in VARCHAR fields with binary collations when calculating hashes.
- return a proper error from create_myisam_from_heap() when conversion fails.
Moved the key statistics update to info().
The table is not locked in open(). This made wrong stats possible.
No test case for the test suite.
This happens only with heavy concurrency.
A test script is added to the bug report.
- If number of records in table is 4, the calculated cost for using "index" and "range" become so close so that any rounding errors becomes visible.
- Added one more record to the tables for heap test and expoect "range" to be selected
- Decrease number of records in t1 for range and expect "index" to be choosen.
