Re: [PATCHES] Patch for JDBC timestamp problems

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: pgman(at)candle(dot)pha(dot)pa(dot)us
Cc: Barry Lind <barry(at)xythos(dot)com>, pgsql-patches(at)postgresql(dot)org, pgsql-interfaces(at)postgresql(dot)org
Subject: Re: [PATCHES] Patch for JDBC timestamp problems
Date: 2001-01-13 18:53:17
Message-ID: 200101131853.NAA20477@candle.pha.pa.us
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Lists: pgsql-interfaces pgsql-patches

I have backed out this patch because of concerns that have been raised.
I would be glad to re-apply it after these issues have been addressed.

> I have applied this patch. It fixes a number of bugs, even one that was
> just reported a few day ago. Thanks.
>
>
> ---------------------------------------------------------------------------
>
>
> 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.
>
> Bug#3) Performance problems
>
> In fixing the above two bugs, I noticed some things that could be
> improved. In PreparedStatement.setTimestamp(),
> PreparedStatement.setDate(), ResultSet.getTimestamp(), and
> ResultSet.getDate() these methods were creating a new SimpleDateFormat
> object everytime they were called. To avoid this unnecessary object
> creation overhead, I changed the code to use static variables for
> keeping a single instance of the needed formating objects.
> Also the code used the + operator for string concatenation. As everyone
> should know this is very inefficient and the use of StringBuffers is
> prefered.
>
> 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(at)internet(dot)com which is also fixed by this patch:
>
> Bug#4) 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.
>
> thanks,
> --Barry
> --------------F902A91CC78EA5B0218A576D
> Content-Type: text/plain; charset=UTF-8; name="patch.diff"
> Content-Transfer-Encoding: 7bit
> Content-Disposition: inline; filename="patch.diff"
>
> *** interfaces/jdbc/org/postgresql/jdbc1/PreparedStatement.java.orig Fri Jan 12 17:17:48 2001
> --- interfaces/jdbc/org/postgresql/jdbc1/PreparedStatement.java Fri Jan 12 17:27:28 2001
> ***************
> *** 310,321 ****
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> public void setDate(int parameterIndex, java.sql.Date x) throws SQLException
> {
> ! SimpleDateFormat df = new SimpleDateFormat("''yyyy-MM-dd''");
> !
> ! set(parameterIndex, df.format(x));
> !
> // The above is how the date should be handled.
> //
> // However, in JDK's prior to 1.1.6 (confirmed with the
> --- 310,320 ----
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> + private static final SimpleDateFormat DF1 = new SimpleDateFormat("yyyy-MM-dd");
> public void setDate(int parameterIndex, java.sql.Date x) throws SQLException
> {
> ! set(parameterIndex, DF1.format(x));
> !
> // The above is how the date should be handled.
> //
> // However, in JDK's prior to 1.1.6 (confirmed with the
> ***************
> *** 349,357 ****
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> public void setTimestamp(int parameterIndex, Timestamp x) throws SQLException
> ! {
> ! set(parameterIndex, "'" + x.toString() + "'");
> }
>
> /**
> --- 348,364 ----
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> + private static SimpleDateFormat DF2 = getDF2();
> + private static SimpleDateFormat getDF2() {
> + SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> + sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
> + return sdf;
> + }
> public void setTimestamp(int parameterIndex, Timestamp x) throws SQLException
> ! {
> ! StringBuffer strBuf = new StringBuffer("'");
> ! strBuf.append(DF2.format(x)).append('.').append(x.getNanos()/10000000).append("+00'");
> ! set(parameterIndex, strBuf.toString());
> }
>
> /**
> *** interfaces/jdbc/org/postgresql/jdbc1/ResultSet.java.orig Fri Jan 12 17:18:45 2001
> --- interfaces/jdbc/org/postgresql/jdbc1/ResultSet.java Fri Jan 12 17:25:02 2001
> ***************
> *** 412,420 ****
> String s = getString(columnIndex);
> if(s==null)
> return null;
> - SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
> try {
> ! return new java.sql.Date(df.parse(s).getTime());
> } catch (ParseException e) {
> throw new PSQLException("postgresql.res.baddate",new Integer(e.getErrorOffset()),s);
> }
> --- 412,419 ----
> String s = getString(columnIndex);
> if(s==null)
> return null;
> try {
> ! return new java.sql.Date(DF5.parse(s).getTime());
> } catch (ParseException e) {
> throw new PSQLException("postgresql.res.baddate",new Integer(e.getErrorOffset()),s);
> }
> ***************
> *** 457,486 ****
> * @return the column value; null if SQL NULL
> * @exception SQLException if a database access error occurs
> */
> public Timestamp getTimestamp(int columnIndex) throws SQLException
> {
> String s = getString(columnIndex);
> if(s==null)
> return null;
> !
> ! // This works, but it's commented out because Michael Stephenson's
> ! // solution is better still:
> ! //SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> !
> ! // Michael Stephenson's solution:
> SimpleDateFormat df = null;
> ! if (s.length()>21 && s.indexOf('.') != -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSzzz");
> ! } else if (s.length()>19 && s.indexOf('.') == -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:sszzz");
> ! } else if (s.length()>19 && s.indexOf('.') != -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:ss.SS");
> ! } else if (s.length()>10 && s.length()<=18) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:ss");
> } else {
> ! df = new SimpleDateFormat("yyyy-MM-dd");
> }
> !
> try {
> return new Timestamp(df.parse(s).getTime());
> } catch(ParseException e) {
> --- 456,514 ----
> * @return the column value; null if SQL NULL
> * @exception SQLException if a database access error occurs
> */
> + private static final SimpleDateFormat DF1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSzzzzzzzzz");
> + private static final SimpleDateFormat DF2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:sszzzzzzzzz");
> + private static final SimpleDateFormat DF3 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
> + private static final SimpleDateFormat DF4 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> + private static final SimpleDateFormat DF5 = new SimpleDateFormat("yyyy-MM-dd");
> public Timestamp getTimestamp(int columnIndex) throws SQLException
> {
> String s = getString(columnIndex);
> if(s==null)
> return null;
> !
> ! boolean subsecond;
> ! //if string contains a '.' we have fractional seconds
> ! if (s.indexOf('.') == -1) {
> ! subsecond = false;
> ! } else {
> ! subsecond = true;
> ! }
> !
> ! //here we are modifying the string from ISO format to a format java can understand
> ! //java expects timezone info as 'GMT-08:00' instead of '-08' in postgres ISO format
> ! //and java expects three digits if fractional seconds are present instead of two for postgres
> ! //so this code strips off timezone info and adds on the GMT+/-...
> ! //as well as adds a third digit for partial seconds if necessary
> ! StringBuffer strBuf = new StringBuffer(s);
> ! char sub = strBuf.charAt(strBuf.length()-3);
> ! if (sub == '+' || sub == '-') {
> ! strBuf.setLength(strBuf.length()-3);
> ! if (subsecond) {
> ! strBuf = strBuf.append('0').append("GMT").append(s.substring(s.length()-3, s.length())).append(":00");
> ! } else {
> ! strBuf = strBuf.append("GMT").append(s.substring(s.length()-3, s.length())).append(":00");
> ! }
> ! } else if (subsecond) {
> ! strBuf = strBuf.append('0');
> ! }
> !
> ! s = strBuf.toString();
> !
> SimpleDateFormat df = null;
> !
> ! if (s.length()>23 && subsecond) {
> ! df = DF1;
> ! } else if (s.length()>23 && !subsecond) {
> ! df = DF2;
> ! } else if (s.length()>10 && subsecond) {
> ! df = DF3;
> ! } else if (s.length()>10 && !subsecond) {
> ! df = DF4;
> } else {
> ! df = DF5;
> }
> !
> try {
> return new Timestamp(df.parse(s).getTime());
> } catch(ParseException e) {
> *** interfaces/jdbc/org/postgresql/jdbc2/PreparedStatement.java.orig Fri Jan 12 17:40:55 2001
> --- interfaces/jdbc/org/postgresql/jdbc2/PreparedStatement.java Fri Jan 12 17:47:42 2001
> ***************
> *** 310,321 ****
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> public void setDate(int parameterIndex, java.sql.Date x) throws SQLException
> {
> ! SimpleDateFormat df = new SimpleDateFormat("''yyyy-MM-dd''");
> !
> ! set(parameterIndex, df.format(x));
> !
> // The above is how the date should be handled.
> //
> // However, in JDK's prior to 1.1.6 (confirmed with the
> --- 310,320 ----
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> + private static final SimpleDateFormat DF1 = new SimpleDateFormat("yyyy-MM-dd");
> public void setDate(int parameterIndex, java.sql.Date x) throws SQLException
> {
> ! set(parameterIndex, DF1.format(x));
> !
> // The above is how the date should be handled.
> //
> // However, in JDK's prior to 1.1.6 (confirmed with the
> ***************
> *** 349,357 ****
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> public void setTimestamp(int parameterIndex, Timestamp x) throws SQLException
> ! {
> ! set(parameterIndex, "'" + x.toString() + "'");
> }
>
> /**
> --- 348,364 ----
> * @param x the parameter value
> * @exception SQLException if a database access error occurs
> */
> + private static SimpleDateFormat DF2 = getDF2();
> + private static SimpleDateFormat getDF2() {
> + SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> + sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
> + return sdf;
> + }
> public void setTimestamp(int parameterIndex, Timestamp x) throws SQLException
> ! {
> ! StringBuffer strBuf = new StringBuffer("'");
> ! strBuf.append(DF2.format(x)).append('.').append(x.getNanos()/10000000).append("+00'");
> ! set(parameterIndex, strBuf.toString());
> }
>
> /**
> *** interfaces/jdbc/org/postgresql/jdbc2/ResultSet.java.orig Fri Jan 12 16:47:28 2001
> --- interfaces/jdbc/org/postgresql/jdbc2/ResultSet.java Fri Jan 12 17:03:03 2001
> ***************
> *** 415,423 ****
> String s = getString(columnIndex);
> if(s==null)
> return null;
> - SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
> try {
> ! return new java.sql.Date(df.parse(s).getTime());
> } catch (ParseException e) {
> throw new PSQLException("postgresql.res.baddate",new Integer(e.getErrorOffset()),s);
> }
> --- 415,422 ----
> String s = getString(columnIndex);
> if(s==null)
> return null;
> try {
> ! return new java.sql.Date(DF5.parse(s).getTime());
> } catch (ParseException e) {
> throw new PSQLException("postgresql.res.baddate",new Integer(e.getErrorOffset()),s);
> }
> ***************
> *** 460,506 ****
> * @return the column value; null if SQL NULL
> * @exception SQLException if a database access error occurs
> */
> public Timestamp getTimestamp(int columnIndex) throws SQLException
> {
> String s = getString(columnIndex);
> if(s==null)
> return null;
> !
> ! // This works, but it's commented out because Michael Stephenson's
> ! // solution is better still:
> ! //SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> ! // Modification by Jan Thomae
> ! String sub = s.substring(s.length() - 3, s.length()-2);
> ! if (sub.equals("+") || sub.equals("-")) {
> ! s = s.substring(0, s.length()-3) + "GMT"+ s.substring(s.length()-3, s.length())+":00";
> }
> ! // -------
> ! // Michael Stephenson's solution:
> SimpleDateFormat df = null;
>
> ! // Modification by Jan Thomae
> ! if (s.length()>27) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:mm:sszzzzzzzzz");
> ! } else
> ! // -------
> ! if (s.length()>21 && s.indexOf('.') != -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSzzz");
> ! } else if (s.length()>19 && s.indexOf('.') == -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:sszzz");
> ! } else if (s.length()>19 && s.indexOf('.') != -1) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:ss.SS");
> ! } else if (s.length()>10 && s.length()<=18) {
> ! df = new SimpleDateFormat("yyyy-MM-dd HH:MM:ss");
> } else {
> ! df = new SimpleDateFormat("yyyy-MM-dd");
> }
> !
> try {
> return new Timestamp(df.parse(s).getTime());
> } catch(ParseException e) {
> throw new PSQLException("postgresql.res.badtimestamp",new Integer(e.getErrorOffset()),s);
> }
> }
>
> /**
> * A column value can be retrieved as a stream of ASCII characters
> --- 459,524 ----
> * @return the column value; null if SQL NULL
> * @exception SQLException if a database access error occurs
> */
> + private static final SimpleDateFormat DF1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSzzzzzzzzz");
> + private static final SimpleDateFormat DF2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:sszzzzzzzzz");
> + private static final SimpleDateFormat DF3 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
> + private static final SimpleDateFormat DF4 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
> + private static final SimpleDateFormat DF5 = new SimpleDateFormat("yyyy-MM-dd");
> public Timestamp getTimestamp(int columnIndex) throws SQLException
> {
> String s = getString(columnIndex);
> if(s==null)
> return null;
> !
> ! boolean subsecond;
> ! //if string contains a '.' we have fractional seconds
> ! if (s.indexOf('.') == -1) {
> ! subsecond = false;
> ! } else {
> ! subsecond = true;
> ! }
> !
> ! //here we are modifying the string from ISO format to a format java can understand
> ! //java expects timezone info as 'GMT-08:00' instead of '-08' in postgres ISO format
> ! //and java expects three digits if fractional seconds are present instead of two for postgres
> ! //so this code strips off timezone info and adds on the GMT+/-...
> ! //as well as adds a third digit for partial seconds if necessary
> ! StringBuffer strBuf = new StringBuffer(s);
> ! char sub = strBuf.charAt(strBuf.length()-3);
> ! if (sub == '+' || sub == '-') {
> ! strBuf.setLength(strBuf.length()-3);
> ! if (subsecond) {
> ! strBuf = strBuf.append('0').append("GMT").append(s.substring(s.length()-3, s.length())).append(":00");
> ! } else {
> ! strBuf = strBuf.append("GMT").append(s.substring(s.length()-3, s.length())).append(":00");
> ! }
> ! } else if (subsecond) {
> ! strBuf = strBuf.append('0');
> }
> !
> ! s = strBuf.toString();
> !
> SimpleDateFormat df = null;
>
> ! if (s.length()>23 && subsecond) {
> ! df = DF1;
> ! } else if (s.length()>23 && !subsecond) {
> ! df = DF2;
> ! } else if (s.length()>10 && subsecond) {
> ! df = DF3;
> ! } else if (s.length()>10 && !subsecond) {
> ! df = DF4;
> } else {
> ! df = DF5;
> }
> !
> try {
> return new Timestamp(df.parse(s).getTime());
> } catch(ParseException e) {
> throw new PSQLException("postgresql.res.badtimestamp",new Integer(e.getErrorOffset()),s);
> }
> }
> +
>
> /**
> * A column value can be retrieved as a stream of ASCII characters
>
> --------------F902A91CC78EA5B0218A576D--
>
>
>
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
> + If your life is a hard drive, | 830 Blythe Avenue
> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026

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