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Follow-on cleanup for the transition table patch.

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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)
This commit is contained in:
Kevin Grittner
2017-04-04 18:36:39 -05:00
parent 9a3215026b
commit 5ebeb579b9
16 changed files with 398 additions and 63 deletions
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21
src/pl/plpython/expected/plpython_trigger.out
View File

@ -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();

5
src/pl/plpython/plpy_exec.c
View File

@ -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);

24
src/pl/plpython/sql/plpython_trigger.sql
View File

@ -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();