I’ll be spending hours in airports this week – I’ll make sure I get something done by next Sunday.

open_cursors is a parameter that limits the number of open cursors (entries in x$kgllk / v$open_cursor) that a single session may create, it has nothing to do with the total number of cursor objects that may exist in the library cache. The limit and Oracle’s behaviour at the limit are confused, however, by the “session cursor cache” (set by parameter session_cached_cursors) and the “pl/sql cursor cache” which allow a session to hold cursors open without explicit calls from the front-end code to do so. The interaction between the three areas of code has changed across versions of Oracle.

As far as I am aware, your session sees Oracle error “ORA-01000: maximum open cursors exceeded” only when it explicitly attempts hold more cursors open than it specificed in open_cursors. (In the early days I used to see this happening relatively frequently in Java-based programs where a programmer instantiated a cursor variable in a class, then discarded the class before closing the cursor).

This note will eventually be tidied up and added to the glossary.

Thank you!