Обсуждение: TIME vs. TIMESTAMP data type
Hi: Are there cases when a TIME data type is a better choice over the TIMESTAMP data type? It seems that PostgreSQL (I'm using 7.2.3) encourage its users to use TIMESTAMP over TIME data type. I said this because of the following: a) More functions for DATE and TIMESTAMP data types such as to_date() and to_timestamp(). Howver, function to_time() does not exist. b) Same amount of storage for TIMESTAMP and for TIME. Time with time zone even need more storage space than a timestamp (12 bytes vs. 8 bytes). c) It's harder to TIMESTAMP to TIME and vice versa, while its easier to cast TIMESTAMP to DATE and vice versa. thank you very much, ludwig __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com
Ludwig Lim wrote: > Hi: > > Are there cases when a TIME data type is a better > choice over the TIMESTAMP data type? > > It seems that PostgreSQL (I'm using 7.2.3) > encourage its users to use TIMESTAMP over TIME data > type. I said this because of the following: > a) More functions for DATE and TIMESTAMP data types > such as to_date() and to_timestamp(). Howver, function > to_time() does not exist. > b) Same amount of storage for TIMESTAMP and for > TIME. Time with time zone even need more storage space > than a timestamp (12 bytes vs. 8 bytes). > c) It's harder to TIMESTAMP to TIME and vice versa, > while its easier to cast TIMESTAMP to DATE and vice > versa. > > > thank you very much, > > ludwig Probably you are right, but you can cast into timestamp before using these functions. Do you really need to care amount of storage? Don't forget about INTERVAL type, which is very useful for time calculations. Regards, Tomasz Myrta
Hi Tomasz: --- Tomasz Myrta <jasiek@klaster.net> wrote: > > Probably you are right, but you can cast into > timestamp before using these functions. > Do you really need to care amount of storage? I was just thinking if both TIMESTAMP and TIME have use the same amount of space (I was think TIME might use less space since it doesn't need to store month, year, day as compared to TIMESTAMP), and TIMESTAMP have more functions and is easier to cast, I might as well use TIMESTAMP. > Don't forget about INTERVAL type, which is very > useful for time calculations. > --> I'll check that one out. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com
On 6/2/03 11:04, "Ludwig Lim" <lud_nowhere_man@yahoo.com> wrote: > Are there cases when a TIME data type is a better > choice over the TIMESTAMP data type? Surely this depends on the nature of the data that you want to represent? If you're researching into sleep patterns and want to represent the times each day that subjects say they tend to wake and/or fall asleep, you may want the TIME type, as the important aspect is the time, not the date. The inclusion of a date would be nonsensical. If you want to record *when* an event occurred, you usually want date and time, so TIMESTAMP is more appropriate. Since event timing is a much more frequent requirement than a time-of-day, it's not surprising that the facilities may be better developed for dealing with that type. Julian Scarfe