BULK COLLECT with a LIMIT clause is the most efficient method for processing large datasets. It reduces context switching between the SQL and PL/SQL engines by fetching rows in batches (e.g., 100 at a time), which optimizes performance and provides control over memory usage. A simple CURSOR FOR loop fetches one row at a time, which is slower for large volumes.

The DETERMINISTIC keyword must be used for a function called from SQL when its result depends solely on its input parameters and causes no side effects. This tells the optimizer that for the same inputs, the function will always return the same result, which is crucial for correctness in queries and allows for potential performance optimizations.

A SQL aggregate function (e.g., SUM, AVG, MAX) called on an empty set returns NULL. If this result is assigned to a NOT NULL variable or used in a context that expects a value, it can cause an implicit NO_DATA_FOUND exception. This is a common, non-obvious source of this exception distinct from a failed SELECT…INTO.

To get a complete diagnostic picture, you need all three: FORMAT_ERROR_STACK gives the error code and message chain. FORMAT_ERROR_BACKTRACE provides the precise line number where the error was raised. FORMAT_CALL_STACK shows the execution call stack (the path of subprogram calls). Together, they allow for comprehensive error logging and debugging.

Oracle does not support AFTER COMMIT triggers directly. The requirement for logic to execute after a commit must be implemented differently, typically using Advanced Queuing (AQ), a scheduler job, or an autonomous transaction procedure that logs data for post-commit processing. The other trigger types fire for each statement or row, not upon commit.

The EXISTS(n) method returns TRUE if the element at the specified index ‘n’ exists in the collection. This is the most direct and safe way to check for an element’s existence before accessing it, preventing SUBSCRIPT_BEYOND_COUNT (for sparse associative arrays or elements beyond COUNT) or NO_DATA_FOUND (for deleted elements) errors.

The primary performance concern with autonomous transactions inside a loop is that each call performs a separate commit. Excessive committing increases redo generation, forces log file sync waits, and can severely impact performance and scalability. The design should be reviewed to batch audit records if possible.

The %ISOPEN cursor attribute returns TRUE if the specified cursor is currently open. It is the correct and necessary check to perform before operations like closing a cursor or fetching from it, to avoid an INVALID_CURSOR exception. The other attributes (%FOUND, %NOTFOUND, %ROWCOUNT) are only valid after a fetch attempt on an open cursor.

The FUNCTION RESULT_CACHE is explicitly designed for this scenario. It caches the function’s input parameters and result in the SGA. Subsequent calls with the same parameters return the cached result without re-executing the function body or query, providing massive performance gains for frequently called, data-intensive functions with stable data.

BULK COLLECT with a LIMIT clause is the most efficient method for processing large datasets. It reduces context switching between the SQL and PL/SQL engines by fetching rows in batches (e.g., 100 at a time), which optimizes performance and provides control over memory usage. A simple CURSOR FOR loop fetches one row at a time, which is slower for large volumes.0