Set up Development Environment

Clone, Build

git clone https://github.com/postgres/postgres
cd postgres

./configure \
  --prefix=$(pwd)/.install \
  --enable-debug \
  --enable-cassert \
  --without-icu
bear - make
make install
export PATH=$(pwd)/.install/bin:$PATH

Initial database cluster

initdb -D .data

Configure Clangd

compile_commands.json: make with bear

.clangd:

If:
  PathMatch: .*\.h$
CompileFlags:
  Add:
    - -include postgres.h

Debug

Configure .vscode/launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Debug PostgreSQL Backend",
            "type": "cppdbg",
            "request": "launch",
            "program": "${workspaceFolder}/.install/bin/postgres",
            "args": [
                "-D", "${workspaceFolder}/.data",
                "-p", "5432",
                "-c", "log_statement=all",
                "-c", "log_min_messages=debug1"
            ],
            "cwd": "${workspaceFolder}",
            "environment": [
                {
                    "name": "PGDATA",
                    "value": "${workspaceFolder}/.data"
                },
                {
                    "name": "PATH",
                    "value": "${workspaceFolder}/.install/bin:${env:PATH}"
                }
            ],
            "MIMode": "lldb"
        },
        {
            "name": "Attach to PostgreSQL Backend",
            "type": "cppdbg",
            "request": "attach",
            "program": "${workspaceFolder}/.install/bin/postgres",
            "processId": "${command:pickProcess}",
            "MIMode": "lldb"
        }
    ]
} 

Debug PostMaster

Debug Worker

pg_ctl -D .data -l .data/logfile start
psql postgres

Then check which process is serving this session.

postgres=# select pg_backend_pid();
 pg_backend_pid 
----------------
          59407
(1 row)

Attach to this pid.