Re: Source for tim=nnnnn in 10046 trace

From: Yong Huang <yong321_at_yahoo.com>
Date: Mon, 26 Aug 2013 19:04:37 -0700 (PDT)
Message-ID: <1377569077.17020.YahooMailNeo_at_web184804.mail.gq1.yahoo.com>

Tony,
I thought about that. But at the end of December or beginning of January, it's not summer. So DST won't be in effect.

I also thought about when the US started it. According to http://en.wikipedia.org/wiki/Daylight_saving_time "It became widely adopted, particularly in North America and Europe starting in the 1970s as a result of the 1970s energy crisis." It didn't say exactly when. But the beginning of 1970 is barely in the 1970s. But of course the epoch time could be put back retrospectively, and when they did it, it happened to be in a summer.

Yong Huang

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 From: De DBA <dedba_at_tpg.com.au>
To: oracle-l_at_freelists.org; yong321_at_yahoo.com Sent: Monday, August 26, 2013 8:47 PM
Subject: Re: Source for tim=nnnnn in 10046 trace  

the 4 hours time difference also occurs in the UTC-5 zone (New York, Detroit, Miami) when Daylight Savings Time is in force.

Cheers,
Tony

On 27/08/13 00:54, Yong Huang wrote:
> One addition to what I posted earlier (shown below). The derived_sysdate in the query is 1969-12-31 19:59:59, i.e. 8pm instead of 23:59:59 of that night (or 12am of 1970-01-01). The 4 hour difference may be due to different timezones. According to
> http://www.timeanddate.com/worldclock/converted.html?iso700101T00&p1=0&p29&p3#&p4(3&p5(6
>
> 8pm of 1969-12-31 at UTC epoch is the time for the timezone where Nova Scotia, Canada is. I'm not sure why.
>
> Yong Huang
>
> My previous message:
>
>
> You just need to change your sysdate to 2013-08-23 15:24:25.823. For example:
>
> SQL> with x as (select 1377285865823053 as t, (1377285865823053/1e6) as t1 from dual)
>    2  select t tim_micro, t1 tim_sec, '2013-08-23 15:24:25' curr_sysdate, to_date('2013-08-23 15:24:25','yyyy-mm-dd hh24:mi:ss')-(t1/86400)
>    3  derived_sysdate
>    4  from x;
>
>            TIM_MICRO              TIM_SEC CURR_SYSDATE        DERIVED_SYSDATE
> -------------------- -------------------- ------------------- -------------------
>      1377285865823053    1377285865.823053 2013-08-23 15:24:25 1969-12-31 19:59:59
>
> The derived sysdate is the epoch.
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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Received on Tue Aug 27 2013 - 04:04:37 CEST