Hacking PostgreSQL, writing patches or creating extensions, might seem intimidating at first. The PostgreSQL codebase is huge and ever-evolving. In this talk, I will show how Eclipse, with the help of gdb, can make it a lot more accessible. In this interactive talk, we will add the PostgreSQL project and set up gdb inside Eclipse. Then, we will walk step through the code using the debugger to reveal some of PostgreSQL internal data structures. We will show how to see the call stacks of errors and crashes, which saves a lot of headaches during development. Finally, we will show how to add a user-defined function that's written in C. At the end of the talk, the audience will be more familiar with a simple but powerful environment to hack PostgreSQL.

1. Hacking PostgreSQL with
Eclipse
Metin Döşlü
metin@citusdata.com
PGCONF.EU 2017
1

2. Motivation
2
Postgres can’t do everything
You can extend it
Eclipse makes it easy

3. Extensions
3
postGIS - Spatial and Geographic objects
pg_cron - Run periodic jobs
hll - HyperLogLog (approximate distinct count)
citus - Scale across multiple machines

4. Personal Story
4
Distributed PostgreSQL PostgreSQL Extension

5. Why Eclipse?
5
Start Fast
Easy Navigation
Rich Features

6. Demo Outline
6
PostgreSQL Inside Eclipse
Walking Around
Deep Dive

7. Demo Outline
7
PostgreSQL Inside Eclipse
Walking Around
Deep Dive

8. Build PostgreSQL
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./configure CFLAGS=-"O0 -g"
make -s -j4
sudo make install

9. Import PostgreSQL into Eclipse
9
File -> Import
C/C++ -> Existing Code as Makefile Project
Turn off scalability mode (optional)

10. Demo Outline
10
PostgreSQL Inside Eclipse
Walking Around
Deep Dive

11. Attach GDB
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select pg_backend_pid();
Debug As -> Debug Configurations
C/C++ Attach to Application

12. PostgreSQL Data Structures
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Variables window
p pprint(parse)
printf "%s", pretty_format_node_dump(nodeToString(parse))
Preferences -> C/C++ -> Debug -> GDB -> Check “Show the GDB traces...”

13. Errors
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errstart() in elog.c
if (elevel >= ERROR)

14. Crashes
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pg_crasher

15. Demo Outline
15
PostgreSQL Inside Eclipse
Walking Around
Deep Dive

16. Gatekeeper
16
watch

17. Demo Outline
17
PostgreSQL Inside Eclipse
Walking Around
Deep Dive

18. Summary
18
Postgres can’t do everything
You can extend
Eclipse makes it easy

19. Hacking PostgreSQL with
Eclipse
Metin Döşlü
metin@citusdata.com
PGCONF.EU 2017
19