are treated more like 'cancel' interrupts: the signal handler sets a
flag that is examined at well-defined spots, rather than trying to cope
with an interrupt that might happen anywhere. See pghackers discussion
of 1/12/01.
---------------------------------------------------------------------------
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.
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@internet.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.
Barry Lind
are now critical sections, so as to ensure die() won't interrupt us while
we are munging shared-memory data structures. Avoid insecure intermediate
states in some code that proc_exit will call, like palloc/pfree. Rename
START/END_CRIT_CODE to START/END_CRIT_SECTION, since that seems to be
what people tend to call them anyway, and make them be called with () like
a function call, in hopes of not confusing pg_indent.
I doubt that this is sufficient to make SIGTERM safe anywhere; there's
just too much code that could get invoked during proc_exit().
- Fix handling of --tables=* (multiple tables never worked properly, AFAICT)
- strdup() the current user in DB routines
- Check results of IO routines more carefully.
- Check results of PQ routines more carefully.
Have not fixed index output yet.
entry:
----------------------------
revision 1.2
date: 2000/12/04 01:20:38; author: tgl; state: Exp; lines:
+18 -18
Eliminate some of the more blatant platform-dependencies ... it
builds here now, anyway ...
----------------------------
Which basically changes u_int*_t -> uint*_t, so now it does not
compile neither under Debian 2.2 nor under NetBSD 1.5 which
is platform independent<B8> all right. Also it replaces $KAME$
with $Id$ which is Bad Thing. PostgreSQL Id should be added as a
separate line so the file history could be seen.
So here is patch:
* changes uint*_t -> uint*. I guess that was the original
intention
* adds uint64 type to include/c.h because its needed
[somebody should check if I did it right]
* adds back KAME Id, because KAME is the master repository
* removes stupid c++ comments in pgcrypto.c
* removes <sys/types.h> from the code, its not needed
--
marko
Marko Kreen
- no more elog(STOP) in StartupXLOG();
- both checkpoint' undo & redo are used to define
oldest on-line log file.
2. Ability to pre-allocate a few log files at checkpoint time
(wal_files option). Off by default.
as both a GROUP BY item and an output expression, the top-level Group
node should just copy up the evaluated expression value from its input,
rather than re-evaluating the expression. Aside from any performance
benefit this might offer, this avoids a crash when there is a sub-SELECT
in said expression.
before calling RelationInvalidateHeapTuple(), which is bad because the
latter needs to look at the tuple data, which is in the shared disk
buffer. If another backend manages to recycle the buffer while this
is going on, we will compute the wrong hashindex for the tuple or
maybe even crash outright. Must hold buffer refcount until afterwards.
(This bug is not in 7.0.*; seems to be have introduced during WAL changes.)
and burn. Just for added luck, change reading of CONST nodes so that
we do not need to consult pg_type rows while reading them; this means
that no database access occurs during stringToNode. This requires
changing the order in which const-node fields are written, which means
an initdb is forced.
in per-entry sub-memory-context, where they were supposed to go, rather
than in CacheMemoryContext where the code was putting them. Must've
suffered a severe brain fade when I wrote this :-(
sequences. This is done by disabling multi-byte awareness when it's
not necessary. This is kind of a workaround, not a perfect solution.
However, there is no ideal way to parse broken multi-byte character
sequences. So I guess this is the best way what we could do right
now...
and revert documentation to describe the existing INHERITS clause
instead, per recent discussion in pghackers. Also fix implementation
of SQL_inheritance SET variable: it is not cool to look at this var
during the initial parsing phase, only during parse_analyze(). See
recent bug report concerning misinterpretation of date constants just
after a SET TIMEZONE command. gram.y really has to be an invariant
transformation of the query string to a raw parsetree; anything that
can vary with time must be done during parse analysis.
Tom Lane