first commit for openGauss connect odbc code

docs/msdtc_pgxalib_tracing_README.txt

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+The files:
+
+  msdtc_pgxalib_tracing_enable.reg
+  msdtc_pgxalib_tracing_disable.reg
+
+are Windows Registry Editor files that can be opened to add registry entries
+that turn psqlODBC's tracing for the Microsoft Distributed Transaction
+Co-Ordinator (MSDTC) on and off.
+
+You must also create C:\pgdtclog and ensure NETWORKSERVICE has write
+permissions. (It will by default on most Windows installs). At time of writing
+the trace path is hard coded to this location.
+
+This tracing is separate to regular ODBC API tracing and to psqlODBC's "mylog"
+tracing. It only traces access to the XA transaction manager used by MSDTC when
+doing XA transaction co-ordination. You probably only need this if you're
+debugging issues with "In doubt" or "only failed to notify" transactions in
+MSDTC.
+
+
+If you're tracing XA transactions in MSDTC you probably also want to trace
+MSDTC its self. For that, see:
+
+http://msdn.microsoft.com/en-us/library/ms684379(v=vs.85).aspx
+http://msdn.microsoft.com/en-us/library/ms678917(v=vs.85).aspx
+
+Tests suggest that only some SDKs' versions of the tracefmt.exe tool required
+will work - I found that Windows SDK 7.1's worked, but Visual Studio Express
+for Desktop 2012's didn't. Your results may vary.