In several cases you do want to truncate, just at a certain resolution lower than seconds, e.g. 100th of a second.
> -----Original Message----- > From: Dinkar Rao [mailto:[EMAIL PROTECTED] > Sent: Saturday, 28 June 2008 4:54 a.m. > To: dev@openjpa.apache.org > Subject: Re: [jira] Closed: (OPENJPA-645) Date millisecond precision lost > for Informix IDS and SQLServer > > 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> > > 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 <[EMAIL PROTECTED]> > 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:[EMAIL PROTECTED] > >> >> 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. > >> > > >> > > >> > > >> > >
