Multiple database + pconnect issues

[eluser]-sek[/eluser]
I'm not sure I follow this, but today I had a problem with a perfectly valid query that was failing. I output the generated SQL and tested it in phpMyAdmin. It worked fine. In my CI based site, it would fail. After some time, I thought what have I changed recently? It was disabling the default persistent connections in the database config and after enabling them again, the query worked fine.

I thought with data abstraction, the same query should work whether persistent connections were enabled or not. I can understand when querying between servers, but my query was not exotic. It seemed strange a valid query would work with one and not the other.

I even commented out the code and put in a simple SELECT statement and it did the same thing. Yet, other queries and parts of the site continued to work.

Is there some explanation for this?