Why is the integer size limit different on Rails when using PostgreSQL v. MySQL?

Question

I'm migrating my app from MySQL to Postgres. If I do a rake db:schema:load, it loads fine into Postgres, and all my tests pass.

If I do rake db:migrate:reset, then an integer column that I had previously set to have :limit => 1 is set to have :limit => 2.

My migration sets it like so:

t.integer "foo", :limit => 1, :null => false

Is it simply a matter of Postgres having a lower minimum size?

Erwin Brandstetter · Accepted Answer · 2012-04-13 23:11:18Z

6

The smallint type in PostgreSQL occupies two byte and accepts numbers from -32768 to +32767.

There is no tinyint like in MySQL that occupies 1 byte and accepts numbers from -128 to 127.

answered Apr 11, 2012 at 4:21

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Comments

Lukas Eklund · Accepted Answer · 2012-04-11 04:22:09Z

3

Postgres doesn't provide a 1-byte integer type. The smallest datatype for integer is the 2-byte smallint.

answered Apr 11, 2012 at 4:22

Lukas Eklund

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