Follow-on cleanup for the transition table patch.

Commit 59702716 added transition table support to PL/pgsql so that
SQL queries in trigger functions could access those transient
tables.  In order to provide the same level of support for PL/perl,
PL/python and PL/tcl, refactor the relevant code into a new
function SPI_register_trigger_data.  Call the new function in the
trigger handler of all four PLs, and document it as a public SPI
function so that authors of out-of-tree PLs can do the same.

Also get rid of a second QueryEnvironment object that was
maintained by PL/pgsql.  That was previously used to deal with
cursors, but the same approach wasn't appropriate for PLs that are
less tangled up with core code.  Instead, have SPI_cursor_open
install the connection's current QueryEnvironment, as already
happens for SPI_execute_plan.

While in the docs, remove the note that transition tables were only
supported in C and PL/pgSQL triggers, and correct some ommissions.

Thomas Munro with some work by Kevin Grittner (mostly docs)

11 files changed, 167 insertions, 50 deletions

diff --git a/src/pl/plperl/expected/plperl_trigger.out b/src/pl/plperl/expected/plperl_trigger.out
index 5e3860ef97b..28011cd9f64 100644
--- a/src/pl/plperl/expected/plperl_trigger.out
+++ b/src/pl/plperl/expected/plperl_trigger.out
@@ -241,6 +241,35 @@ $$ LANGUAGE plperl;
 SELECT direct_trigger();
 ERROR:  trigger functions can only be called as triggers
 CONTEXT:  compilation of PL/Perl function "direct_trigger"
+-- check that SQL run in trigger code can see transition tables
+CREATE TABLE transition_table_test (id int, name text);
+INSERT INTO transition_table_test VALUES (1, 'a');
+CREATE FUNCTION transition_table_test_f() RETURNS trigger LANGUAGE plperl AS
+$$
+    my $cursor = spi_query("SELECT * FROM old_table");
+    my $row = spi_fetchrow($cursor);
+    defined($row) || die "expected a row";
+    elog(INFO, "old: " . $row->{id} . " -> " . $row->{name});
+    my $row = spi_fetchrow($cursor);
+    !defined($row) || die "expected no more rows";
+
+    my $cursor = spi_query("SELECT * FROM new_table");
+    my $row = spi_fetchrow($cursor);
+    defined($row) || die "expected a row";
+    elog(INFO, "new: " . $row->{id} . " -> " . $row->{name});
+    my $row = spi_fetchrow($cursor);
+    !defined($row) || die "expected no more rows";
+
+    return undef;
+$$;
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+UPDATE transition_table_test SET name = 'b';
+INFO:  old: 1 -> a
+INFO:  new: 1 -> b
+DROP TABLE transition_table_test;
+DROP FUNCTION transition_table_test_f();
 -- test plperl command triggers
 create or replace function perlsnitch() returns event_trigger language plperl as $$
   elog(NOTICE, "perlsnitch: " . $_TD->{event} . " " . $_TD->{tag} . " ");
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index 00979cba743..1de770b2505 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -2442,11 +2442,18 @@ plperl_trigger_handler(PG_FUNCTION_ARGS)
 	SV		   *svTD;
 	HV		   *hvTD;
 	ErrorContextCallback pl_error_context;
+	TriggerData *tdata;
+	int 		rc PG_USED_FOR_ASSERTS_ONLY;
 
 	/* Connect to SPI manager */
 	if (SPI_connect() != SPI_OK_CONNECT)
 		elog(ERROR, "could not connect to SPI manager");
 
+	/* Make transition tables visible to this SPI connection */
+	tdata = (TriggerData *) fcinfo->context;
+	rc = SPI_register_trigger_data(tdata);
+	Assert(rc >= 0);
+
 	/* Find or compile the function */
 	prodesc = compile_plperl_function(fcinfo->flinfo->fn_oid, true, false);
 	current_call_data->prodesc = prodesc;
diff --git a/src/pl/plperl/sql/plperl_trigger.sql b/src/pl/plperl/sql/plperl_trigger.sql
index a375b401ea2..624193b9d08 100644
--- a/src/pl/plperl/sql/plperl_trigger.sql
+++ b/src/pl/plperl/sql/plperl_trigger.sql
@@ -170,6 +170,38 @@ $$ LANGUAGE plperl;
 
 SELECT direct_trigger();
 
+-- check that SQL run in trigger code can see transition tables
+
+CREATE TABLE transition_table_test (id int, name text);
+INSERT INTO transition_table_test VALUES (1, 'a');
+
+CREATE FUNCTION transition_table_test_f() RETURNS trigger LANGUAGE plperl AS
+$$
+    my $cursor = spi_query("SELECT * FROM old_table");
+    my $row = spi_fetchrow($cursor);
+    defined($row) || die "expected a row";
+    elog(INFO, "old: " . $row->{id} . " -> " . $row->{name});
+    my $row = spi_fetchrow($cursor);
+    !defined($row) || die "expected no more rows";
+
+    my $cursor = spi_query("SELECT * FROM new_table");
+    my $row = spi_fetchrow($cursor);
+    defined($row) || die "expected a row";
+    elog(INFO, "new: " . $row->{id} . " -> " . $row->{name});
+    my $row = spi_fetchrow($cursor);
+    !defined($row) || die "expected no more rows";
+
+    return undef;
+$$;
+
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+UPDATE transition_table_test SET name = 'b';
+
+DROP TABLE transition_table_test;
+DROP FUNCTION transition_table_test_f();
+
 -- test plperl command triggers
 create or replace function perlsnitch() returns event_trigger language plperl as $$
   elog(NOTICE, "perlsnitch: " . $_TD->{event} . " " . $_TD->{tag} . " ");
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 43da986fc0a..8d7c7caa1c6 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -689,46 +689,9 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
 	else
 		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");
 
-	/*
-	 * Capture the NEW and OLD transition TABLE tuplestores (if specified for
-	 * this trigger).
-	 */
-	if (trigdata->tg_newtable || trigdata->tg_oldtable)
-	{
-		estate.queryEnv = create_queryEnv();
-		if (trigdata->tg_newtable)
-		{
-			EphemeralNamedRelation enr =
-			  palloc(sizeof(EphemeralNamedRelationData));
-			int rc PG_USED_FOR_ASSERTS_ONLY;
-
-			enr->md.name = trigdata->tg_trigger->tgnewtable;
-			enr->md.reliddesc = RelationGetRelid(trigdata->tg_relation);
-			enr->md.tupdesc = NULL;
-			enr->md.enrtype = ENR_NAMED_TUPLESTORE;
-			enr->md.enrtuples = tuplestore_tuple_count(trigdata->tg_newtable);
-			enr->reldata = trigdata->tg_newtable;
-			register_ENR(estate.queryEnv, enr);
-			rc = SPI_register_relation(enr);
-			Assert(rc >= 0);
-		}
-		if (trigdata->tg_oldtable)
-		{
-			EphemeralNamedRelation enr =
-			  palloc(sizeof(EphemeralNamedRelationData));
-			int rc PG_USED_FOR_ASSERTS_ONLY;
-
-			enr->md.name = trigdata->tg_trigger->tgoldtable;
-			enr->md.reliddesc = RelationGetRelid(trigdata->tg_relation);
-			enr->md.tupdesc = NULL;
-			enr->md.enrtype = ENR_NAMED_TUPLESTORE;
-			enr->md.enrtuples = tuplestore_tuple_count(trigdata->tg_oldtable);
-			enr->reldata = trigdata->tg_oldtable;
-			register_ENR(estate.queryEnv, enr);
-			rc = SPI_register_relation(enr);
-			Assert(rc >= 0);
-		}
-	}
+	/* Make transition tables visible to this SPI connection */
+	rc = SPI_register_trigger_data(trigdata);
+	Assert(rc >= 0);
 
 	/*
 	 * Assign the special tg_ variables
@@ -3483,9 +3446,6 @@ plpgsql_estate_setup(PLpgSQL_execstate *estate,
 	estate->paramLI->paramMask = NULL;
 	estate->params_dirty = false;
 
-	/* default tuplestore cache to "none" */
-	estate->queryEnv = NULL;
-
 	/* set up for use of appropriate simple-expression EState and cast hash */
 	if (simple_eval_estate)
 	{
@@ -7373,9 +7333,6 @@ exec_dynquery_with_params(PLpgSQL_execstate *estate,
 	/* Release transient data */
 	MemoryContextReset(stmt_mcontext);
 
-	/* Make sure the portal knows about any named tuplestores. */
-	portal->queryEnv = estate->queryEnv;
-
 	return portal;
 }
 
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 43a62ef34e4..abb19035b66 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -20,7 +20,6 @@
 #include "commands/event_trigger.h"
 #include "commands/trigger.h"
 #include "executor/spi.h"
-#include "utils/queryenvironment.h"
 
 /**********************************************************************
  * Definitions
@@ -911,9 +910,6 @@ typedef struct PLpgSQL_execstate
 	ParamListInfo paramLI;
 	bool		params_dirty;	/* T if any resettable datum has been passed */
 
-	/* custom environment for parsing/execution of query for this context */
-	QueryEnvironment *queryEnv;
-
 	/* EState to use for "simple" expression evaluation */
 	EState	   *simple_eval_estate;
 
diff --git a/src/pl/plpython/expected/plpython_trigger.out b/src/pl/plpython/expected/plpython_trigger.out
index 4148963f3a2..d7ab8ac6b8e 100644
--- a/src/pl/plpython/expected/plpython_trigger.out
+++ b/src/pl/plpython/expected/plpython_trigger.out
@@ -503,3 +503,24 @@ SELECT * FROM b;
  1234
 (1 row)
 
+-- check that SQL run in trigger code can see transition tables
+CREATE TABLE transition_table_test (id int, name text);
+INSERT INTO transition_table_test VALUES (1, 'a');
+CREATE FUNCTION transition_table_test_f() RETURNS trigger LANGUAGE plpythonu AS
+$$
+    rv = plpy.execute("SELECT * FROM old_table")
+    assert(rv.nrows() == 1)
+    plpy.info("old: " + str(rv[0]["id"]) + " -> " + rv[0]["name"])
+    rv = plpy.execute("SELECT * FROM new_table")
+    assert(rv.nrows() == 1)
+    plpy.info("new: " + str(rv[0]["id"]) + " -> " + rv[0]["name"])
+    return None
+$$;
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+UPDATE transition_table_test SET name = 'b';
+INFO:  old: 1 -> a
+INFO:  new: 1 -> b
+DROP TABLE transition_table_test;
+DROP FUNCTION transition_table_test_f();
diff --git a/src/pl/plpython/plpy_exec.c b/src/pl/plpython/plpy_exec.c
index 697a0e1cc03..7ccd2c82352 100644
--- a/src/pl/plpython/plpy_exec.c
+++ b/src/pl/plpython/plpy_exec.c
@@ -345,6 +345,11 @@ PLy_exec_trigger(FunctionCallInfo fcinfo, PLyProcedure *proc)
 
 	PG_TRY();
 	{
+		int		rc PG_USED_FOR_ASSERTS_ONLY;
+
+		rc = SPI_register_trigger_data(tdata);
+		Assert(rc >= 0);
+
 		plargs = PLy_trigger_build_args(fcinfo, proc, &rv);
 		plrv = PLy_procedure_call(proc, "TD", plargs);
 
diff --git a/src/pl/plpython/sql/plpython_trigger.sql b/src/pl/plpython/sql/plpython_trigger.sql
index a054fe729bc..79c24b714b5 100644
--- a/src/pl/plpython/sql/plpython_trigger.sql
+++ b/src/pl/plpython/sql/plpython_trigger.sql
@@ -406,3 +406,27 @@ SELECT * FROM a;
 DROP TABLE a;
 INSERT INTO b DEFAULT VALUES;
 SELECT * FROM b;
+
+-- check that SQL run in trigger code can see transition tables
+
+CREATE TABLE transition_table_test (id int, name text);
+INSERT INTO transition_table_test VALUES (1, 'a');
+
+CREATE FUNCTION transition_table_test_f() RETURNS trigger LANGUAGE plpythonu AS
+$$
+    rv = plpy.execute("SELECT * FROM old_table")
+    assert(rv.nrows() == 1)
+    plpy.info("old: " + str(rv[0]["id"]) + " -> " + rv[0]["name"])
+    rv = plpy.execute("SELECT * FROM new_table")
+    assert(rv.nrows() == 1)
+    plpy.info("new: " + str(rv[0]["id"]) + " -> " + rv[0]["name"])
+    return None
+$$;
+
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+UPDATE transition_table_test SET name = 'b';
+
+DROP TABLE transition_table_test;
+DROP FUNCTION transition_table_test_f();
diff --git a/src/pl/tcl/expected/pltcl_queries.out b/src/pl/tcl/expected/pltcl_queries.out
index 7300b315d64..5f50f468878 100644
--- a/src/pl/tcl/expected/pltcl_queries.out
+++ b/src/pl/tcl/expected/pltcl_queries.out
@@ -660,3 +660,24 @@ select tcl_eval($$
  
 (1 row)
 
+-- test transition table visibility
+create table transition_table_test (id int, name text);
+insert into transition_table_test values (1, 'a');
+create function transition_table_test_f() returns trigger language pltcl as
+$$
+  spi_exec -array C "SELECT id, name FROM old_table" {
+    elog INFO "old: $C(id) -> $C(name)"
+  }
+  spi_exec -array C "SELECT id, name FROM new_table" {
+    elog INFO "new: $C(id) -> $C(name)"
+  }
+  return OK
+$$;
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+update transition_table_test set name = 'b';
+INFO:  old: 1 -> a
+INFO:  new: 1 -> b
+drop table transition_table_test;
+drop function transition_table_test_f();
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index b8fcf0673d3..5a48e5d175a 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -1039,6 +1039,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 	const char *result;
 	int			result_Objc;
 	Tcl_Obj   **result_Objv;
+	int			rc PG_USED_FOR_ASSERTS_ONLY;
 
 	call_state->trigdata = trigdata;
 
@@ -1046,6 +1047,10 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 	if (SPI_connect() != SPI_OK_CONNECT)
 		elog(ERROR, "could not connect to SPI manager");
 
+	/* Make transition tables visible to this SPI connection */
+	rc = SPI_register_trigger_data(trigdata);
+	Assert(rc >= 0);
+
 	/* Find or compile the function */
 	prodesc = compile_pltcl_function(fcinfo->flinfo->fn_oid,
 									 RelationGetRelid(trigdata->tg_relation),
diff --git a/src/pl/tcl/sql/pltcl_queries.sql b/src/pl/tcl/sql/pltcl_queries.sql
index 29ed616cd0b..dabd8cd35f0 100644
--- a/src/pl/tcl/sql/pltcl_queries.sql
+++ b/src/pl/tcl/sql/pltcl_queries.sql
@@ -216,3 +216,23 @@ select tcl_eval($$
   after 100 {set ::tcl_vwait 1}
   vwait ::tcl_vwait
   unset -nocomplain ::tcl_vwait$$);
+
+-- test transition table visibility
+create table transition_table_test (id int, name text);
+insert into transition_table_test values (1, 'a');
+create function transition_table_test_f() returns trigger language pltcl as
+$$
+  spi_exec -array C "SELECT id, name FROM old_table" {
+    elog INFO "old: $C(id) -> $C(name)"
+  }
+  spi_exec -array C "SELECT id, name FROM new_table" {
+    elog INFO "new: $C(id) -> $C(name)"
+  }
+  return OK
+$$;
+CREATE TRIGGER a_t AFTER UPDATE ON transition_table_test
+  REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
+  FOR EACH STATEMENT EXECUTE PROCEDURE transition_table_test_f();
+update transition_table_test set name = 'b';
+drop table transition_table_test;
+drop function transition_table_test_f();