Em 04/12/2012 11:50, Pavel Stehule escreveu:
Hello
2012/12/4 Edson Richter <edsonrichter@xxxxxxxxxxx>:
I think I already know the answer (char(14)), but I would like to confirm:
which is faster?
In Brazil, company id has 14 digits (12 identifiers, 2 control digits). By
today, application use varchar(14) for these, but I intend to optimize
insert/update/delete and search, and I'm considering to change it to
char(14).
Will it give ANY gain? I do use equality and like operators for search.
There are no big differences between char and varchar - char can be
little bit slower, because empty chars to limit are filled by space.
So usually varchar is more effective (in PostgreSQL).
In this specific case, the full length (14) is mandatory... so seems
there is no loss or gain.
Also, I see all varchar(...) created are by default "storage = EXTENDED"
(from "Pg Admin"), while other datatypes (like numeric, smallint,
integer) are "storage = MAIN".
Can I have a gain using fixed length datatype in place of current
varchar (like "numeric (14,0)")?
Or changing to "char(14) check length(doc)=14" and "storage=MAIN"?
Sorry if there are many questions in one, but I'm in a brainstorm...
Thanks,
Edson
Regards
Pavel Stehule
Regards,
Edson
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