Add pg_analyze_and_rewrite_varparams()

This new function extracts common code from PrepareQuery() and
exec_parse_message().  It is then exactly analogous to the existing
pg_analyze_and_rewrite_fixedparams() and
pg_analyze_and_rewrite_withcb().

To unify these two code paths, this makes PrepareQuery() now subject
to log_parser_stats.  Also, both paths now invoke
TRACE_POSTGRESQL_QUERY_REWRITE_START().  PrepareQuery() no longer
checks whether a utility statement was specified.  The grammar doesn't
allow that anyway, and exec_parse_message() supports it, so
restricting it doesn't seem necessary.

This also adds QueryEnvironment support to the *varparams functions,
for consistency with its cousins, even though it is not used right
now.

Reviewed-by: Nathan Bossart <bossartn@amazon.com>
Discussion: https://www.postgresql.org/message-id/flat/c67ce276-52b4-0239-dc0e-39875bf81840@enterprisedb.com

1 files changed, 64 insertions, 31 deletions

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index c087db44456..d7e39aed64b 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -637,9 +637,11 @@ pg_parse_query(const char *query_string)
  * NOTE: for reasons mentioned above, this must be separate from raw parsing.
  */
 List *
-pg_analyze_and_rewrite_fixedparams(RawStmt *parsetree, const char *query_string,
-					   const Oid *paramTypes, int numParams,
-					   QueryEnvironment *queryEnv)
+pg_analyze_and_rewrite_fixedparams(RawStmt *parsetree,
+								   const char *query_string,
+								   const Oid *paramTypes,
+								   int numParams,
+								   QueryEnvironment *queryEnv)
 {
 	Query	   *query;
 	List	   *querytree_list;
@@ -670,6 +672,59 @@ pg_analyze_and_rewrite_fixedparams(RawStmt *parsetree, const char *query_string,
 
 /*
  * Do parse analysis and rewriting.  This is the same as
+ * pg_analyze_and_rewrite_fixedparams except that it's okay to deduce
+ * information about $n symbol datatypes from context.
+ */
+List *
+pg_analyze_and_rewrite_varparams(RawStmt *parsetree,
+								 const char *query_string,
+								 Oid **paramTypes,
+								 int *numParams,
+								 QueryEnvironment *queryEnv)
+{
+	Query	   *query;
+	List	   *querytree_list;
+
+	TRACE_POSTGRESQL_QUERY_REWRITE_START(query_string);
+
+	/*
+	 * (1) Perform parse analysis.
+	 */
+	if (log_parser_stats)
+		ResetUsage();
+
+	query = parse_analyze_varparams(parsetree, query_string, paramTypes, numParams,
+						  queryEnv);
+
+	/*
+	 * Check all parameter types got determined.
+	 */
+	for (int i = 0; i < *numParams; i++)
+	{
+		Oid			ptype = (*paramTypes)[i];
+
+		if (ptype == InvalidOid || ptype == UNKNOWNOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDETERMINATE_DATATYPE),
+					 errmsg("could not determine data type of parameter $%d",
+							i + 1)));
+	}
+
+	if (log_parser_stats)
+		ShowUsage("PARSE ANALYSIS STATISTICS");
+
+	/*
+	 * (2) Rewrite the queries, as necessary
+	 */
+	querytree_list = pg_rewrite_query(query);
+
+	TRACE_POSTGRESQL_QUERY_REWRITE_DONE(query_string);
+
+	return querytree_list;
+}
+
+/*
+ * Do parse analysis and rewriting.  This is the same as
  * pg_analyze_and_rewrite_fixedparams except that, instead of a fixed list of
  * parameter datatypes, a parser callback is supplied that can do
  * external-parameter resolution and possibly other things.
@@ -1409,7 +1464,6 @@ exec_parse_message(const char *query_string,	/* string to execute */
 
 	if (parsetree_list != NIL)
 	{
-		Query	   *query;
 		bool		snapshot_set = false;
 
 		raw_parse_tree = linitial_node(RawStmt, parsetree_list);
@@ -1449,34 +1503,13 @@ exec_parse_message(const char *query_string,	/* string to execute */
 		/*
 		 * Analyze and rewrite the query.  Note that the originally specified
 		 * parameter set is not required to be complete, so we have to use
-		 * parse_analyze_varparams().
-		 */
-		if (log_parser_stats)
-			ResetUsage();
-
-		query = parse_analyze_varparams(raw_parse_tree,
-										query_string,
-										&paramTypes,
-										&numParams);
-
-		/*
-		 * Check all parameter types got determined.
+		 * pg_analyze_and_rewrite_varparams().
 		 */
-		for (int i = 0; i < numParams; i++)
-		{
-			Oid			ptype = paramTypes[i];
-
-			if (ptype == InvalidOid || ptype == UNKNOWNOID)
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_DATATYPE),
-						 errmsg("could not determine data type of parameter $%d",
-								i + 1)));
-		}
-
-		if (log_parser_stats)
-			ShowUsage("PARSE ANALYSIS STATISTICS");
-
-		querytree_list = pg_rewrite_query(query);
+		querytree_list = pg_analyze_and_rewrite_varparams(raw_parse_tree,
+														  query_string,
+														  &paramTypes,
+														  &numParams,
+														  NULL);
 
 		/* Done with the snapshot used for parsing */
 		if (snapshot_set)