Date millisecond precision lost for Informix IDS and SQLServer
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Key: OPENJPA-645
URL: https://issues.apache.org/jira/browse/OPENJPA-645
Project: OpenJPA
Issue Type: Bug
Components: jdbc
Reporter: Dinkar Rao
Priority: Minor
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.
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