Re: [HACKERS] Data type removal

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> From: dg(at)illustra(dot)com (David Gould)
> > Speaking of data type removal, I was wondering if there were a better
> > way to handle arrays of types. From looking in the catalog, it
> > appears that for each type, there is also declared a similar type,
> > which is the array version. It seems that arrays should be considered
> > more flags on a field, than a field type in themselves. Does this
> > make sense to anybody else?
>
> Is an array the same thing as a scalar?
Uhm, I don't believe so.

> What would be the benefit of making arrays "flags on a field" instead of
> a "field type in themselves". Seriously, how would this improve _anything_?

In particular, I was thinking of the PostgreSQL module for Python. It
has a nice interface, but needs intimate knowledge of the data types.
Somehow, it seems to be excessively kludgy to have to have e.g. an
int4 type, and an int4[] type. When I query a table, if one of the
fields is an array of integers, then I either want to know that it's
an array, or it's integer. If the returned type is "array," then I
have to magically know that the array is filled with integers. If
it's an integer, then I just have to recognize that it's actually a
series of integers. With the current setup, there has to be separate
type handlers for char(2), char(2)[], int4, int4[], int2, int2[],
float8, float8[], etcetera. I'd rather have handlers for the base
type, and an iterator that's used for arrays.

> What is the motivation for data type removal?

In this case, I don't want to *remove* the data type, just change the
identification method. An array of int4 should really be recognized
as both (type)int4 and (type)array. Urhm, since this is PostgreSQL, I
guess I'm arguing for type composition (how appropriate for an
object-relational database).

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