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From "Kevin Sutter" <kwsut...@gmail.com>
Subject Re: [jira] Closed: (OPENJPA-645) Date millisecond precision lost for Informix IDS and SQLServer
Date Fri, 27 Jun 2008 17:00:55 GMT
Thanks for the clarification, Dinkar.

On Fri, Jun 27, 2008 at 11:53 AM, Dinkar Rao <dinkar.d91411118@gmail.com>
wrote:

> The warnings about Sybase, SQLServer, and Infomix are just a reminder
> for folks trying to use precise dates in their code. Due to
> limitations in these databases with precision for date types,  what
> you get back from the database might not be what you expect.
>
> On the OpenJPA side, we ensure with this fix that we don't compound
> the problem by truncating milliseconds.
>
> Thanks
> Dinkar
>
> On Fri, Jun 27, 2008 at 5:55 AM, Kevin Sutter <kwsutter@gmail.com> wrote:
> > Should this topic be opened as a separate Issue (or sub-task)?  Or,
> should
> > this Issue just be re-opened?  I'm not an expert with this timestamp
> stuff,
> > but it seems like we still have an open issue with this resolution.
> >
> > Kevin
> >
> > On Thu, Jun 26, 2008 at 4:13 PM, Dinkar Rao <dinkar.d91411118@gmail.com>
> > wrote:
> >
> >> Ditto for SQLServer.
> >>
> >> On IDS, the fractional precision is specifiable upto only 5 places, as
> >> in "udate DATETIME YEAR TO FRACTION(5)".  So the max fractional value
> >> that can be stored is 99999.
> >>
> >> On Thu, Jun 26, 2008 at 1:29 PM, Evan Ireland <eireland@sybase.com>
> wrote:
> >> > Just a note on this for Sybase databases, for which the resolution is
> 1
> >> > 300th of a second. When using O/R mapping with Sybase ASE, it is best
> to
> >> > round the Timestamp value to the nearest 100th of a second when
> storing,
> >> so
> >> > that you don't get unexpected comparison failures when reading the
> value
> >> > back again or using a value in a 'where' clause.
> >> >
> >> >> -----Original Message-----
> >> >> From: Catalina Wei (JIRA) [mailto:jira@apache.org]
> >> >> Sent: Friday, 27 June 2008 8:24 a.m.
> >> >> To: dev@openjpa.apache.org
> >> >> Subject: [jira] Closed: (OPENJPA-645) Date millisecond precision lost
> >> for
> >> >> Informix IDS and SQLServer
> >> >>
> >> >>
> >> >>      [ https://issues.apache.org/jira/browse/OPENJPA-
> >> >> 645?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
> ]
> >> >>
> >> >> Catalina Wei closed OPENJPA-645.
> >> >> --------------------------------
> >> >>
> >> >>     Resolution: Fixed
> >> >>
> >> >> fix checked in under r672017
> >> >>
> >> >> > Date millisecond precision lost for Informix IDS and SQLServer
> >> >> > --------------------------------------------------------------
> >> >> >
> >> >> >                 Key: OPENJPA-645
> >> >> >                 URL:
> >> https://issues.apache.org/jira/browse/OPENJPA-645
> >> >> >             Project: OpenJPA
> >> >> >          Issue Type: Bug
> >> >> >          Components: jdbc
> >> >> >            Reporter: Dinkar Rao
> >> >> >            Priority: Minor
> >> >> >         Attachments: patch-645.txt
> >> >> >
> >> >> >
> >> >> > An entity has an attribute of type java.util.Date, annotated with
> >> >> @Temporal(TemporalType.TIMESTAMP):
> >> >> > @Temporal(TemporalType.TIMESTAMP)
> >> >> > public Date udate;
> >> >> > This gets mapped in Informix to a column of type:
> >> >> > udate DATETIME YEAR TO FRACTION (3)
> >> >> > and in SQLServer to
> >> >> > udate DATETIME
> >> >> > When the udate attribute is assigned a value with millisecond
> >> precision,
> >> >> say "12:34:56:789", OpenJPA chops off the millisecond fractional part
> >> when
> >> >> it generates the INSERT statement.
> >> >> > In DBDictionary, for this type, we come to setDate() with the
'val'
> >> >> parameter set to the correct java.util.Date value "12:34:56:789".
> (The
> >> >> millisecond value is stored in the (Gregorian.Date) cdate.millis
> >> attribute
> >> >> of java.util.Date). setDate() then calls setTimestamp() - the last
> else
> >> -
> >> >> with a new instance of java.sql.Timestamp:
> >> >> > setTimestamp(stmnt, idx, new Timestamp(val.getTime()), null, col);
> >> >> > java.sql.Timestamp is made up of 2 parts - a date part that stores
> the
> >> >> time upto seconds, and a separate attribute, called nanos, that
> stores
> >> >> everything that is fractional of seconds.
> >> >> > So the new Timestamp value that is sent to setTimestamp() has
this:
> >> >> > (Gregorian.Date) cdate = 12:34:56
> >> >> > nanos = 789000000
> >> >> > In setTimestamp() there is a check for supportsTimestampNanos.
> Because
> >> >> in the InformixDictionary and SQLServer dictionaries this is set to
> >> false,
> >> >> the code then zeros out the nanos field:
> >> >> > if (supportsTimestampNanos)
> >> >> >     val.setNanos(nanos);
> >> >> > else
> >> >> >     val.setNanos(0);
> >> >> > Consequently, all fractional seconds information is lost for these
> 2
> >> >> database types from the INSERT statement for this timestamp value.
> >> >> > The nanos field in java.sql.Timestamp does not really mean that
> only
> >> >> nanoseconds are stored there - it means that any fractional value,
> after
> >> >> seconds  will be stored there.This problem happens not only with the
> >> Date
> >> >> field in the entity, but also with java.util.Calendar and
> >> >> java.sql.Timestamp. The solution is to always set the nanoseconds
> value
> >> in
> >> >> the (java.sql.Timestamp)val field. The check for
> supportsTimestampNanos,
> >> >> as well as the flag itself, is not needed, because both IDS and
> >> SQLServer
> >> >> do allow fractional seconds.
> >> >> > Will attach a patch ASAP. Albert has reviewed the proposed
> solution.
> >> >>
> >> >> --
> >> >> This message is automatically generated by JIRA.
> >> >> -
> >> >> You can reply to this email to add a comment to the issue online.
> >> >
> >> >
> >> >
> >>
> >
>

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