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Timestamp accuracy in postgres and upp [message #33055]

Tue, 05 July 2011 15:44

Zbych
Messages: 325
Registered: July 2009

Senior Member

Hi,

Definition of TIME in database schematic doesn't specify accuracy and (at least) postgres keeps time in micro seconds. Since upp time accuracy is 1s, it sometimes leads to some problems. Maybe there should be another definition of TIME that has the same accuracy like upp? What do you think?

My proposition is to add following definitions to PostgreSQLSchema.h:

#define TIME_SEC(x) COLUMN("timestamp(0)", Time, x, 0, 0)
#define TIME_SEC_(x) COLUMN_("timestamp(0)", Time, x, 0, 0)

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Re: Timestamp accuracy in postgres and upp [message #33090 is a reply to message #33055]

Wed, 06 July 2011 14:30

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

Zbych wrote on Tue, 05 July 2011 09:44

Actually, perhaps TIME should be defined in seconds accuracy...

However, what kind of issues does it leads to? I would say you store seconds, you are about retrieve seconds from DB, right?

Mirek

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Re: Timestamp accuracy in postgres and upp [message #33092 is a reply to message #33090]

Wed, 06 July 2011 15:02

Zbych
Messages: 325
Registered: July 2009

Senior Member

I don't want to change TIME definition because of backward compatibility, but it is your decision.

In my application I keep some logs in a database. Once in a while another application transfers those logs from the database to main server and I use timestamp to remember which logs were already transfered.
If the last log has timestamp 17:00:00.5 (timestamp is added automatically by postgres), upp rounds it to 17:00:00. Next time I will search for logs with timestamp >17:00:00 and the log with timestamp 17:00:00.5 will be transfered again. That is why I need the same timestamp resolution in both upp and database.

[Updated on: Wed, 06 July 2011 15:04]

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Re: Timestamp accuracy in postgres and upp [message #33113 is a reply to message #33092]

Thu, 07 July 2011 13:17

zsolt
Messages: 696
Registered: December 2005
Location: Budapest, Hungary

Contributor

I think, it would be easier to use a 'serial' field.

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Re: Timestamp accuracy in postgres and upp [message #33299 is a reply to message #33092]

Sat, 23 July 2011 09:15

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

Zbych wrote on Wed, 06 July 2011 09:02

What I am not getting is why it finds the log the first time, actually...

I mean, if the select is something like

Select().From(LOG).Where(timestamp >= 16:00 && timestamp < 17:00)

(and than move forward).

In fact, I am posting this because I have very similar arrangemnt in one of mine apps, so I would like to know if I am missing something Smile