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Generated columns

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This is an SQL-standard feature that allows creating columns that are
computed from expressions rather than assigned, similar to a view or
materialized view but on a column basis.

This implements one kind of generated column: stored (computed on
write).  Another kind, virtual (computed on read), is planned for the
future, and some room is left for it.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/b151f851-4019-bdb1-699e-ebab07d2f40a@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2019-03-30 08:13:09 +01:00
parent 6b8b5364dd
commit fc22b6623b
84 changed files with 3067 additions and 157 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/pl/plpython/expected/plpython_trigger.out
+94
View File
@@ -67,6 +67,10 @@ SELECT * FROM users;
-- dump trigger data
CREATE TABLE trigger_test
(i int, v text );
CREATE TABLE trigger_test_generated (
i int,
j int GENERATED ALWAYS AS (i * 2) STORED
);
CREATE FUNCTION trigger_data() RETURNS trigger LANGUAGE plpythonu AS $$
if 'relid' in TD:
@@ -203,6 +207,77 @@ NOTICE: TD[when] => BEFORE
DROP TRIGGER show_trigger_data_trig_stmt on trigger_test;
DROP TRIGGER show_trigger_data_trig_before on trigger_test;
DROP TRIGGER show_trigger_data_trig_after on trigger_test;
CREATE TRIGGER show_trigger_data_trig_before
BEFORE INSERT OR UPDATE OR DELETE ON trigger_test_generated
FOR EACH ROW EXECUTE PROCEDURE trigger_data();
CREATE TRIGGER show_trigger_data_trig_after
AFTER INSERT OR UPDATE OR DELETE ON trigger_test_generated
FOR EACH ROW EXECUTE PROCEDURE trigger_data();
insert into trigger_test_generated (i) values (1);
NOTICE: TD[args] => None
NOTICE: TD[event] => INSERT
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_before
NOTICE: TD[new] => {'i': 1}
NOTICE: TD[old] => None
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => BEFORE
NOTICE: TD[args] => None
NOTICE: TD[event] => INSERT
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_after
NOTICE: TD[new] => {'i': 1, 'j': 2}
NOTICE: TD[old] => None
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => AFTER
update trigger_test_generated set i = 11 where i = 1;
NOTICE: TD[args] => None
NOTICE: TD[event] => UPDATE
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_before
NOTICE: TD[new] => {'i': 11}
NOTICE: TD[old] => {'i': 1, 'j': 2}
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => BEFORE
NOTICE: TD[args] => None
NOTICE: TD[event] => UPDATE
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_after
NOTICE: TD[new] => {'i': 11, 'j': 22}
NOTICE: TD[old] => {'i': 1, 'j': 2}
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => AFTER
delete from trigger_test_generated;
NOTICE: TD[args] => None
NOTICE: TD[event] => DELETE
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_before
NOTICE: TD[new] => None
NOTICE: TD[old] => {'i': 11, 'j': 22}
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => BEFORE
NOTICE: TD[args] => None
NOTICE: TD[event] => DELETE
NOTICE: TD[level] => ROW
NOTICE: TD[name] => show_trigger_data_trig_after
NOTICE: TD[new] => None
NOTICE: TD[old] => {'i': 11, 'j': 22}
NOTICE: TD[relid] => bogus:12345
NOTICE: TD[table_name] => trigger_test_generated
NOTICE: TD[table_schema] => public
NOTICE: TD[when] => AFTER
DROP TRIGGER show_trigger_data_trig_before ON trigger_test_generated;
DROP TRIGGER show_trigger_data_trig_after ON trigger_test_generated;
insert into trigger_test values(1,'insert');
CREATE VIEW trigger_test_view AS SELECT * FROM trigger_test;
CREATE TRIGGER show_trigger_data_trig
@@ -524,3 +599,22 @@ INFO: old: 1 -> a
INFO: new: 1 -> b
DROP TABLE transition_table_test;
DROP FUNCTION transition_table_test_f();
-- dealing with generated columns
CREATE FUNCTION generated_test_func1() RETURNS trigger
LANGUAGE plpythonu
AS $$
TD['new']['j'] = 5 # not allowed
return 'MODIFY'
$$;
CREATE TRIGGER generated_test_trigger1 BEFORE INSERT ON trigger_test_generated
FOR EACH ROW EXECUTE PROCEDURE generated_test_func1();
TRUNCATE trigger_test_generated;
INSERT INTO trigger_test_generated (i) VALUES (1);
ERROR: cannot set generated column "j"
CONTEXT: while modifying trigger row
PL/Python function "generated_test_func1"
SELECT * FROM trigger_test_generated;
i | j
---+---
(0 rows)