pgdbg

pgdbg is a small GDB helper for pretty-printing PostgreSQL Node trees, including indexed PostgreSQL List elements, from a live debugging session.

What It Does

• loads a custom pgprint command into GDB
• detects PostgreSQL node pointers and formats them recursively

Requirements

• gdb with Python support
• a debug session where PostgreSQL types are available

This repository includes a Nix dev shell with gdb and python3:

nix develop

Load In GDB

Do not run the Python files directly. Load them from inside GDB:

source /path/to/pgdbg/pgdbg.py

That registers the pgprint command.

Usage

pgprint [--depth MAX_DEPTH] [--position POSITION] <expression>...
pgprint [--depth MAX_DEPTH] [--position POSITION] -- <expression>...

Examples:

pgprint query
pgprint --depth 3 query
pgprint --position 0 query->targetList
pgprint --depth 2 --position 1 query->rtable
pgprint ((Node*)query)

depth must be an integer greater than or equal to 1.

position must be an integer greater than or equal to 0.

Supported Node Formatters

Current specialized formatters live under nodes/:

• T_Query
• T_List
• T_IntList
• T_OidList
• T_XidList

Other structs that look like PostgreSQL nodes still print through the generic base formatter.