in reply to
Using Two Different Database types in Perl
You definitely need to reduce this to a test-case that clearly demonstrates the (minimal) problem. My suspicions of a bug in your program are aroused by what you say ... “the same SQL.” You need to be absolutely certain that you are performing the same steps each time: connect, prepare the SQL query (from a text string), execute the query, close everything, disconnect. Leaving out none of these steps, and not re-using any Perl object. That’s why a short piece of example code is needed.