Comments on: TIMESTAMPs, Old Fogeys, and Data Warehouses

By: David Aldridge

David Aldridge — Tue, 25 Mar 2008 18:05:12 +0000

Yes, it certainly has value when properly used. Handling subsecond dates and timings is painful without it.

Do you generally use the default precision? You mention measuring to 10ms accuracy, so I was wondering if you use TIMESTAMP(3), TIMESTAMP(4) etc or just accept the default.

By: Mette

Mette — Tue, 25 Mar 2008 15:06:14 +0000

Hello :-)

We use TIMESTAMP(6) lots of places, especialy in application where we trace bits of transactions - ie. BPM applications, MessageBrigding - where it matters to the end users if a 2 second duration (DATE) actually IS 2 seconds or just 10 ms because it spans the second limit.

We have not had any problems with it - but we had to read the manuals before doing date arithmatic gymnastics on them though … but that never hurt anyone, did it?

Best regards
Mette

By: David Aldridge

David Aldridge — Mon, 24 Mar 2008 19:39:08 +0000

As a followup, I just found a comment on Informatica’s knowledge base that TIMESTAMP is not even a supported data type.

By: David Aldridge

David Aldridge — Sat, 15 Mar 2008 14:26:43 +0000

Could be I suppose, but if it encourages people to use TIMESTAMP instead of DATE then I’d be wishing there wasn’t. It’d be a bit of an odd feature — deploy your table creation scripts on one database and get different data length to the deployment on a different database.

By: Duke Ganote

Duke Ganote — Sat, 15 Mar 2008 00:32:33 +0000

I wonder if there’s a way to change the default timestamp fractional second precision to zero instead of 6?

By: David Aldridge

David Aldridge — Thu, 13 Mar 2008 00:10:38 +0000

One sad followup is that I requested the replacement of all of these abominations from the schema, but the response I got from the development team suggested that they needed it in order to store hours, minutes and seconds. I didn’t pursue that line with them because the comment was withdrawn pretty quickly, but I wonder whether the 6 in the TIMESTAMP(6) specificaton was actually intended to store hours, minutes and seconds, rather than microseconds. It’s an intriguing possibility.

On the same day I had a comment from another developer that it was really hard to work with those columns because Informatica converted them to character strings, so point proven on the compatibility issue.

However that same developer was writing interesting code along the lines of:

TO_CHAR(update_dt,’MM/DD/YYYY’) > TO_CHAR($$start_date,’MM/DD/YYYY’)

After sending a corrective email I spent quite a while ranting loudly round the office and frothing at the mouth before I realised that he was sitting just a couple of cubes away.

By: Jeff Hunter

Jeff Hunter — Wed, 12 Mar 2008 14:17:04 +0000

I get really turned off when I see a TIMESTAMP data type. I had really bad luck with them when doing a bunch of export/imports and they were slow as molassas. Also the developers think they are a great idea until they have to CAST…AS DATE everytime they want to do something basic. Yuck, but everybody knows the developers know more about the database than the DBAs.

By: Donald K. Burleson

Donald K. Burleson — Fri, 07 Mar 2008 15:27:44 +0000

Hi David,

Welcome back!

>> have I officially turnded into an old fogey now?

Nah . . . .

Regarding DATE datatypes, less is best, IMHO!

We never stop learning, but I’m sure that there will come a day when everyone “locks-down” and stops learning new things.