If we create a temporary table with the same name within a store procedure, and try to drop some columns in two different sessions running at the same moment, error " Unknown column" may pop.

Although this is documented in

https://mariadb.com/kb/en/mariadb/documentation/sql-commands/data-definition/create/create-table/

"Temporary table names are specific to your session. They may conflict with other temporary tables from other sessions or shadow names of non-temporary tables."

But this is different behavior with Mysql

http://dev.mysql.com/doc/refman/5.5/en/create-table.html

This means that two different sessions can use the same temporary table name without conflicting with each other or with an existing non-TEMPORARY table of the same name. (The existing table is hidden until the temporary table is dropped.)

This is stopper if using Mariadb as a drop in replacement for Mysql, as this require rewrite all SPs with alter temporary statement.