First phase of plan-invalidation project: create a plan cache management

module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan).  This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.

Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too.  Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.

1 files changed, 32 insertions, 1 deletions

diff --git a/src/backend/nodes/params.c b/src/backend/nodes/params.c
index 15e7b1d24f1..07593c55470 100644
--- a/src/backend/nodes/params.c
+++ b/src/backend/nodes/params.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/params.c,v 1.8 2007/01/05 22:19:30 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/params.c,v 1.9 2007/03/13 00:33:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -60,3 +60,34 @@ copyParamList(ParamListInfo from)
 
 	return retval;
 }
+
+/*
+ * Extract an array of parameter type OIDs from a ParamListInfo.
+ *
+ * The result is allocated in CurrentMemoryContext.
+ */
+void
+getParamListTypes(ParamListInfo params,
+				  Oid **param_types, int *num_params)
+{
+	Oid		   *ptypes;
+	int			i;
+
+	if (params == NULL || params->numParams <= 0)
+	{
+		*param_types = NULL;
+		*num_params = 0;
+		return;
+	}
+
+	ptypes = (Oid *) palloc(params->numParams * sizeof(Oid));
+	*param_types = ptypes;
+	*num_params = params->numParams;
+
+	for (i = 0; i < params->numParams; i++)
+	{
+		ParamExternData *prm = &params->params[i];
+
+		ptypes[i] = prm->ptype;
+	}
+}