Document a gotcha that happens on Windows when using libpq's new event

procedure support: it's possible to get confused because exported procedures
have two different addresses.  Per Andrew Chernow.

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 0b220ab514b99cc367e3cb622907582a77f183d4..d7b4d2393a168368207824b4b5b14360b241d42c 100644 (file)
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  <application>libpq</application> - C Library
@@ -5255,6 +5255,19 @@ int eventproc(PGEventId evtId, void *evtInfo, void *passThrough)
        PGconn.  This is because the address of the procedure
        is used as a lookup key to identify the associated instance data.
       
+
+      
+       
+        On Windows, functions can have two different addresses: one visible
+        from outside a DLL and another visible from inside the DLL.  One
+        should be careful that only one of these addresses is used with
+        libpq's event-procedure functions, else confusion will
+        result.  The simplest rule for writing code that will work is to
+        ensure that event procedures are declared static.  If the
+        procedure's address must be available outside its own source file,
+        expose a separate function to return the address.
+       
+