Add infrastructure to support EphemeralNamedRelation references.

A QueryEnvironment concept is added, which allows new types of
objects to be passed into queries from parsing on through
execution.  At this point, the only thing implemented is a
collection of EphemeralNamedRelation objects -- relations which
can be referenced by name in queries, but do not exist in the
catalogs.  The only type of ENR implemented is NamedTuplestore, but
provision is made to add more types fairly easily.

An ENR can carry its own TupleDesc or reference a relation in the
catalogs by relid.

Although these features can be used without SPI, convenience
functions are added to SPI so that ENRs can easily be used by code
run through SPI.

The initial use of all this is going to be transition tables in
AFTER triggers, but that will be added to each PL as a separate
commit.

An incidental effect of this patch is to produce a more informative
error message if an attempt is made to modify the contents of a CTE
from a referencing DML statement.  No tests previously covered that
possibility, so one is added.

Kevin Grittner and Thomas Munro
Reviewed by Heikki Linnakangas, David Fetter, and Thomas Munro
with valuable comments and suggestions from many others

1 files changed, 10 insertions, 7 deletions

diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index dc6d43ec6d6..5b3f777f2c3 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -91,7 +91,7 @@ PrepareQuery(PrepareStmt *stmt, const char *queryString,
 	 * to see the unmodified raw parse tree.
 	 */
 	plansource = CreateCachedPlan(rawstmt, queryString,
-								  CreateCommandTag(stmt->query));
+								  CreateCommandTag(stmt->query), NULL);
 
 	/* Transform list of TypeNames to array of type OIDs */
 	nargs = list_length(stmt->argtypes);
@@ -243,7 +243,7 @@ ExecuteQuery(ExecuteStmt *stmt, IntoClause *intoClause,
 									   entry->plansource->query_string);
 
 	/* Replan if needed, and increment plan refcount for portal */
-	cplan = GetCachedPlan(entry->plansource, paramLI, false);
+	cplan = GetCachedPlan(entry->plansource, paramLI, false, NULL);
 	plan_list = cplan->stmt_list;
 
 	/*
@@ -551,7 +551,7 @@ FetchPreparedStatementTargetList(PreparedStatement *stmt)
 	List	   *tlist;
 
 	/* Get the plan's primary targetlist */
-	tlist = CachedPlanGetTargetList(stmt->plansource);
+	tlist = CachedPlanGetTargetList(stmt->plansource, NULL);
 
 	/* Copy into caller's context in case plan gets invalidated */
 	return copyObject(tlist);
@@ -629,7 +629,8 @@ DropAllPreparedStatements(void)
  */
 void
 ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
-					const char *queryString, ParamListInfo params)
+					const char *queryString, ParamListInfo params,
+					QueryEnvironment *queryEnv)
 {
 	PreparedStatement *entry;
 	const char *query_string;
@@ -668,7 +669,7 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
 	}
 
 	/* Replan if needed, and acquire a transient refcount */
-	cplan = GetCachedPlan(entry->plansource, paramLI, true);
+	cplan = GetCachedPlan(entry->plansource, paramLI, true, queryEnv);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
@@ -681,9 +682,11 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
 		PlannedStmt *pstmt = castNode(PlannedStmt, lfirst(p));
 
 		if (pstmt->commandType != CMD_UTILITY)
-			ExplainOnePlan(pstmt, into, es, query_string, paramLI, &planduration);
+			ExplainOnePlan(pstmt, into, es, query_string, paramLI, queryEnv,
+						   &planduration);
 		else
-			ExplainOneUtility(pstmt->utilityStmt, into, es, query_string, paramLI);
+			ExplainOneUtility(pstmt->utilityStmt, into, es, query_string,
+							  paramLI, queryEnv);
 
 		/* No need for CommandCounterIncrement, as ExplainOnePlan did it */