Re: PostgreSQL Developer Best Practices

[Melvin Davidson <melvin6925@xxxxxxxxx>]

I think a lot of people here are missing the point. I was trying to give examples of natural keys, but a lot of people are taking great delight

in pointing out exceptions to examples, rather than understanding the point.

So for the sake of argument, a natural key is something that in itself is unique and the possibility of a duplicate does not exist.

Before ANYONE continues to insist that a serial id column is good, consider the case where the number of tuples will exceed a bigint.

Don't say it cannot happen, because it can.

However, if you have an alphanumeric field, let's say varchar 50, and it's guaranteed that it will never have a duplicate, then THAT is a natural primary

key and beats the hell out of a generic "id" field.

Further to the point, since I started this thread, I am holding to it and will not discuss "natural primary keys" any further.

Other suggestions for good PostgreSQL Developer database (not web app) guidelines are still welcome.

On Tue, Aug 25, 2015 at 7:34 PM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:

On 08/25/2015 04:23 PM, Jerry Sievers wrote:

Adrian Klaver <adrian.klaver@xxxxxxxxxxx> writes:

On 08/25/2015 01:56 PM, John R Pierce wrote:

On 8/25/2015 1:42 PM, Gavin Flower wrote:

Account numbers are externally generated, and may potentially change.
Management might suddenly decide that they want to start using the
year the account started as the first 4 digits, or that the branch
code should be reflected in it, or something else.  The database
should be protected from these arbitrary changes.  Hence the
account_no is not a good candidate for a primary key.

such practices would raise total havoc on a traditional paper ledger
accounting system as well as things like pending AR/AP where external
companies will be referencing your account numbers.

Agreed, but it happens. When Lowes took over a local hardware
chain(Eagles) here in Washington state they moved very quickly on
changing the account numbers. The company I worked for who supplied
Eagles and then Lowes sat on a check for $22,000 that was sent to us
in error because the account numbers got switched. We called them when
we got the check, but it still took them six months to own up to it.

DOH!

Next time a screwball outfit sends you a check for $22k erroneously just
go deposit it :-)

Well that is what I wanted to do, the owner overruled me:(. Something about Lowes having more lawyers then we did. The strange part was we called them and told them what had happened and supplied the relevant information that explained the mix up. You would have thought us calling to return a check that was supposed to be to us would have raised a flag!

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Adrian Klaver
adrian.klaver@xxxxxxxxxxx

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Adrian Klaver
adrian.klaver@xxxxxxxxxxx

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Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.