Dawid Kuroczko wrote:
smallint takes two bytes. Numeric(1) will take around 10 bytes and char(1) will
take 5 bytes (4 bytes for length of data).
I never would've imagined *that* amount of overhead for CHAR(1)! I would've
imagined that it would take up one byte (or two with a NULL indicator). After
all, we're not talking about VARCHAR(1) [which is sort of useless]. Don't the
catalogs know the declared length and if so, why the length overhead? I'm also
surprised --albeit less-- about the NUMERIC(1) overhead. Is any of this
discussed in the Internals chapters? I didn't see this discussed elsewhere.
As a perhaps-related aside, I've noticed several examples which declare string
types as 'text', rather than VARCHAR or CHAR, the former being non-SQL standard.
Is there some performance benefit to using 'text' (other than it being shorter
to type :-) or is it just the "usual Postgres way"?
Joe
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