Background

IvorySQL has a native DBMS_OUTPUT implementation. This issue documents a comparison with orafce's implementation and identifies the remaining gap: SET SERVEROUTPUT ON support.

Architecture Comparison

Buffer Design

IvorySQL (Linked List)

typedef struct DbmsOutputLine {
    struct DbmsOutputLine *next;
    int len;           // -1 for NULL
    char data[FLEXIBLE_ARRAY_MEMBER];
} DbmsOutputLine;

• ✅ O(1) append and pop
• ✅ Memory freed immediately when lines consumed
• ✅ No buffer compaction needed
• ✅ Supports true NULL lines (distinct from empty string)

orafce (Contiguous Buffer)

static char *buffer = NULL;
static int buffer_size, buffer_len, buffer_get;

• ✅ Simpler implementation
• ❌ Must track "already retrieved" offset
• ❌ No memory reclaim until buffer reset
• ❌ NULL lines not distinguishable from empty

Feature Comparison

SERVEROUTPUT Differences

Summary

IvorySQL's implementation is more Oracle-compatible and more memory-efficient:

• ✅ True CREATE PACKAGE syntax (not just schema-qualified functions)
• ✅ Proper NULL line handling (distinct from empty strings)
• ✅ Oracle-compatible error codes (ORU-10027, ORU-10028)
• ✅ 32,767 byte line length limit enforcement
• ✅ DISCARD ALL/PACKAGES support via ProcessUtility hook
• ✅ Better memory efficiency with linked-list design

The only missing feature is SET SERVEROUTPUT ON which would require psql client modifications to match Oracle SQL*Plus syntax exactly.

Proposed SET SERVEROUTPUT Implementation

Oracle's syntax:

SET SERVEROUT[PUT] {OFF | ON} [SIZE {n | UNLIMITED}] [FORMAT {WRAPPED | WORD_WRAPPED | TRUNCATED}]

Implementation approach:

1. Parse SET SERVEROUTPUT in psql's Oracle mode lexer (ora_psqlscanslash.l)
2. Track state in psql settings (serveroutput_enabled, serveroutput_size)
3. After each statement, if enabled, call dbms_output.get_lines() and print results
4. Call dbms_output.enable(size) when turning ON

This matches Oracle's behavior where SERVEROUTPUT is a client-side feature, not a server feature.

References

• orafce source: https://github.com/orafce/orafce
• orafce putline.c: https://github.com/orafce/orafce/blob/master/putline.c
• Oracle DBMS_OUTPUT docs: https://docs.oracle.com/en/database/oracle/oracle-database/19/arpls/DBMS_OUTPUT.html
• Oracle SET SERVEROUTPUT docs: https://www.oreilly.com/library/view/oracle-sql-plus-the/0596007469/re85.html