RE: Store TIME in the Oracle

  • From: "Dunbar, Norman (Capgemini)" <norman.dunbar.capgemini@xxxxxxxxxxxxxxxxxxxxxxxxx>
  • To: <ecandrietta@xxxxxxxxx>, "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
  • Date: Mon, 15 Aug 2011 08:16:04 +0100


>> I will follow this way:
>> to_date('01-JAN-2000 '|| 
>> to_char(sysdate,'HH24:MI:SS'),'DD-MON-YYYY HH24:MI:SS')
>> I will put the date hard code for all lines inserted and the 
>> time that must be saved.

I'm not convinced that that is a good idea. I have a nagging feeling in my head 
that this will confuse the optimiser if it ever needs to take into account this 
column in working out a decent query plan. 

Equally, you'll probably never get the benefit of an index on that column I 
should imagine - but I suspect you won't be using one anyway.

Why not just set your column to sysdate? 

You will save on one concatenation, on to_char() and one to_date() function 
call for every insert. As a quick and highly unscientific test, it takes around 
23.8% longer to do it your way as compared to sysdate only. Over three runs of 
1,000,000 rows inserted. (Very slow PC running Oracle and the database on one 
single disc.)

The date part is irrelevant as you will be selecting only the time part, so why 
not save some CPU etc?

Just my £0.02.


Norman Dunbar
Contract Senior Oracle DBA
Capgemini Database Team (EA)
Internal : 7 28 2051
External : 0113 231 2051

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