26e566446f
objects that Thomas pointed out might be a problem. PPS. I have included and updated the comments from the original patch request to reflect the changes made in this revised patch. > Attached is a set of patches for a couple of bugs dealing with > timestamps in JDBC. > > Bug#1) Incorrect timestamp stored in DB if client timezone different > than DB. > The buggy implementation of setTimestamp() in PreparedStatement simply > used the toString() method of the java.sql.Timestamp object to convert > to a string to send to the database. The format of this is yyyy-MM-dd > hh:mm:ss.SSS which doesn't include any timezone information. Therefore > the DB assumes its timezone since none is specified. That is OK if the > timezone of the client and server are the same, however if they are > different the wrong timestamp is received by the server. For example if > the client is running in timezone GMT and wants to send the timestamp > for noon to a server running in PST (GMT-8 hours), then the server will > receive 2000-01-12 12:00:00.0 and interprete it as 2000-01-12 > 12:00:00-08 which is 2000-01-12 04:00:00 in GMT. The fix is to send a > format to the server that includes the timezone offset. For simplicity > sake the fix uses a SimpleDateFormat object with its timezone set to GMT > so that '+00' can be used as the timezone for postgresql. This is done > as SimpleDateFormat doesn't support formating timezones in the way > postgresql expects. > > Bug#2) Incorrect handling of partial seconds in getting timestamps from > the DB > > When the SimpleDateFormat object parses a string with a format like > yyyy-MM-dd hh:mm:ss.SS it expects the fractional seconds to be three > decimal places (time precision in java is miliseconds = three decimal > places). This seems like a bug in java to me, but it is unlikely to be > fixed anytime soon, so the postgresql code needed modification to > support the java behaviour. So for example a string of '2000-01-12 > 12:00:00.12-08' coming from the database was being converted to a > timestamp object with a value of 2000-01-12 12:00:00.012GMT-08:00. The > fix was to check for a '.' in the string and if one is found append on > an extra zero to the fractional seconds part. > > > I also did some cleanup in ResultSet.getTimestamp(). This method has > had multiple patches applied some of which resulted in code that was no > longer needed. For example the ISO timestamp format that postgresql > uses specifies the timezone as an offset like '-08'. Code was added at > one point to convert the postgresql format to the java one which is > GMT-08:00, however the old code was left around which did nothing. So > there was code that looked for yyyy-MM-dd hh:mm:sszzzzzzzzz and > yyyy-MM-dd hh:mm:sszzz. This second format would never be encountered > because zzz (i.e. -08) would be converted into the former (also note > that the SimpleDateFormat object treats zzzzzzzzz and zzz the same, the > number of z's does not matter). > > > There was another problem/fix mentioned on the email lists today by > mcannon@internet.com which is also fixed by this patch: > > Bug#3) Fractional seconds lost when getting timestamp from the DB > A patch by Jan Thomea handled the case of yyyy-MM-dd hh:mm:sszzzzzzzzz > but not the fractional seconds version yyyy-MM-dd hh:mm:ss.SSzzzzzzzzz. > The code is fixed to handle this case as well. Barry Lind |
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