Hi, Alexander! On Apr 07, Alexander Barkov wrote:
Hi Sergei,
I tested comparison behaviour for various different situations.
Please find the comment with the summary table in the end of: https://mariadb.atlassian.net/browse/MDEV-7649
Currently there are 5 possible reactions on bad bytes on comparison, depending on the collation, presence of an index, and character_set_connection value:
- truncate on bad byte, compare only the well-formed prefix (#1) - treat bad bytes as '?' (#7 and #8) - empty set with no warning (#3) - empty set with a warning (#2) - error (#5 and #6)
I'm in doubts what to do for 10.1 and for 5.5. Please suggest.
1. For 10.1 or 10.2 I think it would be nice to make all these cases work exactly the same way. I am not sure which way would be the best. Any ideas?
I like your last idea from MDEV-7649 - treating invalid symbols as "larger than any valid symbol". If that's doable without major changes.
2. For 5.5 we need to fix the bug with minimal changes. Do you agree? I suggest we fix only #1 and maybe #2.
I'd suggest to fix only #1 - and make the comparison to return an empty set. Regards, Sergei