This document summarizes a lightning talk on pg_reversi, a Reversi game implemented as PostgreSQL functions. Key points: - Pg_reversi allows playing the game Reversi using only PostgreSQL functions called from psql. It is implemented using PL/pgSQL. - An Enterprise Edition adds features like concealing SQL logs to prevent the DBA from seeing gameplay, and setting an application name to mask that it is pg_reversi running. - This allows "lazy employees" to play Reversi at work without bosses knowing, making it a useful tool for "Enterprise companies". - In conclusion, pg_reversi demonstrates playing games solely within

1. PGConf.ASIA Lightning Talk
(2016-12-03)
pg_reversi
ぬこ＠横浜 (@nuko_yokohama)

2. 2
Self-Introduction
Search with the word "PostgreSQL Ramen".
I'm "nuko_yokohama".
I am aiming at PostgreSQL entertainer.

3. 3
The theme about
today.

4. 4
Sorry,
Useless knowledge

5. 5
Solutions for
"Solitaire
employees"

6. 6
pg_reversi

7. 7
Reversi by PostgreSQL

8. 8
pg_reversi SQL Functions.
black(x, y)
white(x,y)
black_pass()
white_pass()
get_turn_boad_status()

9. 9
Implemented byImplemented by
SQL/plpgsql.SQL/plpgsql.
Because, I do not want toBecause, I do not want to
implemented byimplemented by
C language!C language!
絶対に C 言語で書きたくないでござる！

10. 10
Viewer is
implemented psql
script file.
(Used PostgreSQL 9.6
feature “crosstabview”)

11. 11
Viewer script file.
SELECT get_turn_boad_status() AS status;
o /dev/null
SELECT x AS " ", y,
CASE
WHEN status = 1 THEN '●'
WHEN status = -1 THEN '○'
ELSE ' '
END AS status
FROM boad ORDER BY x;
o
crosstabview " " y status y
Point. SELECT result output to /dev/null

12. 12
pg_reversi image

13. 13
pg_reversi
Demonstration

14. 14
Able to play
Reversi with psql!

15. 15
Up to this point is the
explanation of the
"Standard edition".

16. 16
pg_reversi
Enterprise Edition

17. 17
Features
By emit_log_hook, to conceal the SQL
log from pg_reversi application.
static void
pg_reversi_emit_log_hook(ErrorData *data) {
const char* appname = application_name;
if (appname == NULL || *appname == '0') {
/* applicatoin_name is no set */
return ;
}
if (!strcmp(appname, "pg_reversi")) {
/* When application_name is pg_reversi, output to the server log is suppressed. */
data->output_to_server = false;
}
return ;
}

18. 18
Setting the pg_reversi to PostgreSQL
setting "preload_shared_libraries'.
preload_shared_libraries = 'pg_reversi'
In psql not, use the "pg_reversi"
utility (psql copy).
$ pg_reversi -U postgres pg_reversi

19. 19
Show “application_name”
$ psql -U postgres pg_reversi -c "SHOW application_name"
application_name
------------------
psql
(1 row)
$ pg_reversi -U postgres pg_reversi -c "SHOW application_name"
application_name
------------------
pg_reversi
(1 row)

20. 20
Enterprise Edition
Demonstration

21. 21
Standard Edition
Since SQL is output to theSince SQL is output to the
server log, the DBA willserver log, the DBA will
check it!check it!
↓↓
My boss gets angry!My boss gets angry!

22. 22
Enterprise Edition
SQL is not logged.SQL is not logged.
↓↓
DBA and Boss also doesDBA and Boss also does
not notice.not notice.
Everyone is happy.Everyone is happy.
Win-Win!Win-Win!

23. 23
Exactly, feature forExactly, feature for
"Lazy employee in"Lazy employee in
Enterprise company".Enterprise company".

24. 24
Conclusion

25. 25
Reversi can also be
played.
(It can not be used with pgAdmin4!)

26. 26
Only on theOnly on the
PostgreSQL….PostgreSQL….

27. 27
End.