Insert conditional SPI_push/SPI_pop calls into InputFunctionCall,

OutputFunctionCall, and friends.  This allows SPI-using functions to invoke
datatype I/O without concern for the possibility that a SPI-using function
will be called (which could be either the I/O function itself, or a function
used in a domain check constraint).  It's a tad ugly, but not nearly as ugly
as what'd be needed to make this work via retail insertion of push/pop
operations in all the PLs.

This reverts my patch of 2007-01-30 that inserted some retail SPI_push/pop
calls into plpgsql; that approach only fixed plpgsql, and not any other PLs.
But the other PLs have the issue too, as illustrated by a recent gripe from
Christian Schröder.

Back-patch to 8.2, which is as far back as this solution will work.  It's
also as far back as we need to worry about the domain-constraint case, since
earlier versions did not attempt to check domain constraints within datatype
input.  I'm not aware of any old I/O functions that use SPI themselves, so
this should be sufficient for a back-patch.

1 files changed, 2 insertions, 29 deletions

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 74fc6d60335..6096eb9e100 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.180.2.6 2008/09/01 22:30:48 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.180.2.7 2009/01/07 20:39:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -4288,27 +4288,11 @@ make_tuple_from_row(PLpgSQL_execstate *estate,
 static char *
 convert_value_to_string(Datum value, Oid valtype)
 {
-	char	   *str;
 	Oid			typoutput;
 	bool		typIsVarlena;
 
 	getTypeOutputInfo(valtype, &typoutput, &typIsVarlena);
-
-	/*
-	 * We do SPI_push to allow the datatype output function to use SPI.
-	 * However we do not mess around with CommandCounterIncrement or advancing
-	 * the snapshot, which means that a stable output function would not see
-	 * updates made so far by our own function.  The use-case for such
-	 * scenarios seems too narrow to justify the cycles that would be
-	 * expended.
-	 */
-	SPI_push();
-
-	str = OidOutputFunctionCall(typoutput, value);
-
-	SPI_pop();
-
-	return str;
+	return OidOutputFunctionCall(typoutput, value);
 }
 
 /* ----------
@@ -4334,25 +4318,14 @@ exec_cast_value(Datum value, Oid valtype,
 			char	   *extval;
 
 			extval = convert_value_to_string(value, valtype);
-
-			/* Allow input function to use SPI ... see notes above */
-			SPI_push();
-
 			value = InputFunctionCall(reqinput, extval,
 									  reqtypioparam, reqtypmod);
-
-			SPI_pop();
-
 			pfree(extval);
 		}
 		else
 		{
-			SPI_push();
-
 			value = InputFunctionCall(reqinput, NULL,
 									  reqtypioparam, reqtypmod);
-
-			SPI_pop();
 		}
 	}