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, 28 insertions, 12 deletions

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index ea19ba60c59..a18ab436167 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -55,7 +55,8 @@ explain_get_index_name_hook_type explain_get_index_name_hook = NULL;
 
 static void ExplainOneQuery(Query *query, int cursorOptions,
 				IntoClause *into, ExplainState *es,
-				const char *queryString, ParamListInfo params);
+				const char *queryString, ParamListInfo params,
+				QueryEnvironment *queryEnv);
 static void report_triggers(ResultRelInfo *rInfo, bool show_relname,
 				ExplainState *es);
 static double elapsed_time(instr_time *starttime);
@@ -142,7 +143,8 @@ static void escape_yaml(StringInfo buf, const char *str);
  */
 void
 ExplainQuery(ParseState *pstate, ExplainStmt *stmt, const char *queryString,
-			 ParamListInfo params, DestReceiver *dest)
+			 ParamListInfo params, QueryEnvironment *queryEnv,
+			 DestReceiver *dest)
 {
 	ExplainState *es = NewExplainState();
 	TupOutputState *tstate;
@@ -253,7 +255,7 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt, const char *queryString,
 		{
 			ExplainOneQuery(castNode(Query, lfirst(l)),
 							CURSOR_OPT_PARALLEL_OK, NULL, es,
-							queryString, params);
+							queryString, params, queryEnv);
 
 			/* Separate plans with an appropriate separator */
 			if (lnext(l) != NULL)
@@ -338,12 +340,14 @@ ExplainResultDesc(ExplainStmt *stmt)
 static void
 ExplainOneQuery(Query *query, int cursorOptions,
 				IntoClause *into, ExplainState *es,
-				const char *queryString, ParamListInfo params)
+				const char *queryString, ParamListInfo params,
+				QueryEnvironment *queryEnv)
 {
 	/* planner will not cope with utility statements */
 	if (query->commandType == CMD_UTILITY)
 	{
-		ExplainOneUtility(query->utilityStmt, into, es, queryString, params);
+		ExplainOneUtility(query->utilityStmt, into, es, queryString, params,
+						  queryEnv);
 		return;
 	}
 
@@ -366,7 +370,8 @@ ExplainOneQuery(Query *query, int cursorOptions,
 		INSTR_TIME_SUBTRACT(planduration, planstart);
 
 		/* run it (if needed) and produce output */
-		ExplainOnePlan(plan, into, es, queryString, params, &planduration);
+		ExplainOnePlan(plan, into, es, queryString, params, queryEnv,
+					   &planduration);
 	}
 }
 
@@ -383,7 +388,8 @@ ExplainOneQuery(Query *query, int cursorOptions,
  */
 void
 ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
-				  const char *queryString, ParamListInfo params)
+				  const char *queryString, ParamListInfo params,
+				  QueryEnvironment *queryEnv)
 {
 	if (utilityStmt == NULL)
 		return;
@@ -404,7 +410,7 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
 		Assert(list_length(rewritten) == 1);
 		ExplainOneQuery(castNode(Query, linitial(rewritten)),
 						0, ctas->into, es,
-						queryString, params);
+						queryString, params, queryEnv);
 	}
 	else if (IsA(utilityStmt, DeclareCursorStmt))
 	{
@@ -423,11 +429,11 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
 		Assert(list_length(rewritten) == 1);
 		ExplainOneQuery(castNode(Query, linitial(rewritten)),
 						dcs->options, NULL, es,
-						queryString, params);
+						queryString, params, queryEnv);
 	}
 	else if (IsA(utilityStmt, ExecuteStmt))
 		ExplainExecuteQuery((ExecuteStmt *) utilityStmt, into, es,
-							queryString, params);
+							queryString, params, queryEnv);
 	else if (IsA(utilityStmt, NotifyStmt))
 	{
 		if (es->format == EXPLAIN_FORMAT_TEXT)
@@ -460,7 +466,7 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
 void
 ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 			   const char *queryString, ParamListInfo params,
-			   const instr_time *planduration)
+			   QueryEnvironment *queryEnv, const instr_time *planduration)
 {
 	DestReceiver *dest;
 	QueryDesc  *queryDesc;
@@ -505,7 +511,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 	/* Create a QueryDesc for the query */
 	queryDesc = CreateQueryDesc(plannedstmt, queryString,
 								GetActiveSnapshot(), InvalidSnapshot,
-								dest, params, instrument_option);
+								dest, params, queryEnv, instrument_option);
 
 	/* Select execution options */
 	if (es->analyze)
@@ -796,6 +802,7 @@ ExplainPreScanNode(PlanState *planstate, Bitmapset **rels_used)
 		case T_TableFuncScan:
 		case T_ValuesScan:
 		case T_CteScan:
+		case T_NamedTuplestoreScan:
 		case T_WorkTableScan:
 			*rels_used = bms_add_member(*rels_used,
 										((Scan *) plan)->scanrelid);
@@ -951,6 +958,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
 		case T_CteScan:
 			pname = sname = "CTE Scan";
 			break;
+		case T_NamedTuplestoreScan:
+			pname = sname = "Named Tuplestore Scan";
+			break;
 		case T_WorkTableScan:
 			pname = sname = "WorkTable Scan";
 			break;
@@ -1389,6 +1399,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
 		case T_SeqScan:
 		case T_ValuesScan:
 		case T_CteScan:
+		case T_NamedTuplestoreScan:
 		case T_WorkTableScan:
 		case T_SubqueryScan:
 			show_scan_qual(plan->qual, "Filter", planstate, ancestors, es);
@@ -2679,6 +2690,11 @@ ExplainTargetRel(Plan *plan, Index rti, ExplainState *es)
 			objectname = rte->ctename;
 			objecttag = "CTE Name";
 			break;
+		case T_NamedTuplestoreScan:
+			Assert(rte->rtekind == RTE_NAMEDTUPLESTORE);
+			objectname = rte->enrname;
+			objecttag = "Tuplestore Name";
+			break;
 		case T_WorkTableScan:
 			/* Assert it's on a self-reference CTE */
 			Assert(rte->rtekind == RTE_CTE);