How I work with Postgres – psql, My PostgreSQL Admin - Craig Kerstiens

On at least a weekly basis and not uncommonly multiple times in a single week I get this question:

Sometimes it leans more to, what is the Sequel Pro equivilant for Postgres. My default answer is I just use psql, though I do have to then go on to explain how I use it. For those just interested you can read more below or just get the highlights here:

• Set your default EDITOR then use \e
• On postgres 9.2 and up \x auto is your friend
• Set history to unlimited
• \d all the things

Before going into detail on why psql works perfectly fine as an interface I want to rant for a minute about what the problems with current editors are and where I expect them to go in the future. First this is not a knock on the work thats been done on previous ones, for their time PgAdmin, phpPgAdmin, and others were valuable tools, but we’re coming to a point where theres a broader set of users of databases than ever before and empowering them is becoming ever more important.

Empowering developers, DBA’s, product people, marketers and others to be comfortable with their database will lead to more people taking advantage of whats in their data. pg_stat_statements was a great start to this laying a great foundation for valuable information being captured. Even with all of the powerful stats being captured in the statistics of PostgreSQL so many are still terrified when they see something like:

 QUERY PLAN
----------------------------------------------------------------------------------------------------------------
 Hash Join (cost=4.25..8.62 rows=100 width=107) (actual time=0.126..0.230 rows=100 loops=1)
 Hash Cond: (purchases.user_id = users.id)
 -> Seq Scan on purchases (cost=0.00..3.00 rows=100 width=84) (actual time=0.012..0.035 rows=100 loops=1)
 -> Hash (cost=3.00..3.00 rows=100 width=27) (actual time=0.097..0.097 rows=100 loops=1)
 Buckets: 1024 Batches: 1 Memory Usage: 6kB
 -> Seq Scan on users (cost=0.00..3.00 rows=100 width=27) (actual time=0.007..0.042 rows=100 loops=1)
 Total runtime: 0.799 ms
(7 rows)

Empowering more developers by surfacing this information in a digestable form, such as building on top of pg_stat_statements tools such as datascope by @leinweber and getting this to be part of the default admin we will truly begin empowering a new set of user.

But enough of a detour, those tools aren’t available today. If you’re interested in helping build those to make the community better please reach out. For now I live in a work where I’m quite content with simple ole psql here’s how:

Editor

Ensuring you’ve exported your preferred editor to the environment variable EDITOR when you run \e it will allow you to view and edit your last run query in your editor of choice. This works for vim, emacs, or even sublime text.

export EDITOR=subl
psql
\e 

Gives me:

Note you need to make sure you connect with psql and have your editor set, once you do that saving and exiting the file will then execute the query

\x auto

psql has long had a method of formatting output. You can toggle this on and off easily by just running the \x command. Running a basic query you get the output:

SELECT * 
FROM users 
LIMIt 1;
 id | first_name | last_name | email | data | created_at | updated_at | last_login
 ----+------------+-----------+----------------------------+------------+---------------------+---------------------+---------------------
 1 | Rosemary | Wassink | Rosemary.Wassink@yahoo.com | "sex"=>"F" | 2010-07-01 18:16:00 | 2011-05-14 11:47:00 | 2011-06-07 23:04:00

With toggling the output and re-running the same query we can see how its now formatted:

\x
Expanded display is on.
craig=# SELECT * from users limit 1;
-[ RECORD 1 ]--------------------------
id | 1
first_name | Rosemary
last_name | Wassink
email | Rosemary.Wassink@yahoo.com
data | "sex"=>"F"
created_at | 2010-07-01 18:16:00
updated_at | 2011-05-14 11:47:00
last_login | 2011-06-07 23:04:00

Using \x auto will automatically put this in what Postgres believes is the most intelligible format to read it in.

psql history

Hopefully this needs no justification… having an unlimited history of all your queries is incredibly handy. Ensuring you set the following environment variables will ensure you never lose that query you ran several months ago again:

export HISTFILESIZE=
export HISTSIZE=

\d

And while the last on the list one of the first things I do when connecting to any database is check out whats in it. I don’t do this by running a bunch of queries but rather checking out the schema and then poking at definitions of specific tables. \d and variations on it are incredibly handy for this. Here’s a few highlights below:

Listing all relations with simply \d:

\d
 List of relations
 Schema | Name | Type | Owner
--------+------------------+---------------+-------
 public | products | table | craig
 public | products_id_seq | sequence | craig
 public | purchases | table | craig
 public | purchases_id_seq | sequence | craig
 public | redis_db0 | foreign table | craig
 public | users | table | craig
 public | users_id_seq | sequence | craig
(7 rows)

List only all tables with dt:

\dt
 List of relations
 Schema | Name | Type | Owner
--------+-----------+-------+-------
 public | products | table | craig
 public | purchases | table | craig
 public | users | table | craig
(3 rows)

Describe a specific relation with \d RELATIONNAMEHERE:

\d users
 Table "public.users"
 Column | Type | Modifiers
------------+-----------------------------+----------------------------------------------------
 id | integer | not null default nextval('users_id_seq'::regclass)
 first_name | character varying(50) |
 last_name | character varying(50) |
 email | character varying(255) |
 data | hstore |
 created_at | timestamp without time zone |
 updated_at | timestamp without time zone |
 last_login | timestamp without time zone |

Have a tool you prefer, have something you use daily in psql that I missed, or interested in helping create a new admin experience please reach out and lets talk craig.kerstiens at gmail.com