Crystal <support@xxxxxxxxxxxxxxxxxxx> writes: > Our company need to save contact details into the PostgreSQL database. I > just begin to learn it, so I got many questions. I am not sure which > data type I should choose for website address, varchar or char. Use varchar. Or text, if you don't have a specific upper limit in mind. > The website address may be very long, and we also don't want to lose the > speed. Thus, the question is: if we have a large contact database, how > much slowdown or speed up will be expected if we choose variable length > rather than fixed length? Thanks forward. Once upon a time, in the days of 80-column punch cards and no variable-length character encodings, there were databases that could handle fixed-width character fields a bit faster than variable-width. That doesn't apply to Postgres. There is no, none, nada performance advantage to char(n), and you should never use it unless your application data clearly demands a specific field width. regards, tom lane
