RE: r there downsides to explicitly naming a pk column xxxx_pk

My personal preference is {table_name}_key for primary keys.

Reason 1

Should you use a NATURAL JOIN the common column will only appear once in the set of returned columns.

http://www.postgresqltutorial.com/postgresql-natural-join/

Reason 2

It removes ambiguity.

"foo.id" can easily be mis-typed as "bar.id" and a query might still run, with possible nasty side effects. That can catch you out if it has been a long day!

If you type "bar.foo_id" instead of "foo.foo_id" the query will fail as table and column do not match.

Reason 3 (a)

It's unlikely that the primary key on a table might change, but I don't like to tie function (data type, index status) to the name of a column. e.g. I would never use "unique_email_address" or "text_total".

Reason 3 (b)

A primary key might consist of one column initially, but then might expand to become a composite key, at that point you have to start renaming columns.

On 14 December 2017 at 20:41, Gavin Flower <GavinFlower@archidevsys.co.nz> wrote:

On 12/15/2017 09:22 AM, David G. Johnston wrote:

On Thu, Dec 14, 2017 at 1:14 PM, john snow <ofbizfanster@gmail.com <mailto:ofbizfanster@gmail.com>>wrote:

    instead of the more conventional xxxx_id or just id?

    sorry if this may be a foolish question to some, but i'm trying to
    think thru
    a junior colleagues's proposal. the discussion occurred while we were
    discussing naming our foreign key constraints using the convention
    "childtable_parenttable_colname_fk".

​Are you talking about the constraint name or the name of the column holding the data?​

​Identifiers in PostgreSQL can only be 64 characters (bytes?) long.

If it is the column name I wouldn't get too crazy or people writing out SQL joins manually will be asking you to pay their medical bills...

I generally avoid naming any column "id" - tables get short code aliases and those prefix the "id".  I then name the column in the FK the exact same name.  I rely on system defaults for choosing the names of the corresponding constraints and indexes.

David J.

I use 'id' for the primary key of the current table, and 'xxx-id' for a foreign key.

So it is easy to identify the primary key, and to spot the foreign keys.

Since we know the current table name, it is redundant to name the table's primary key with the its table name.


Cheers,
Gavin