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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
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94
src/pl/plpython/expected/plpython_trigger.out
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)

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

@ -357,7 +357,7 @@ PLy_cursor_iternext(PyObject *self)
exec_ctx->curr_proc);
ret = PLy_input_from_tuple(&cursor->result, SPI_tuptable->vals[0],
SPI_tuptable->tupdesc);
SPI_tuptable->tupdesc, true);
}
SPI_freetuptable(SPI_tuptable);
@ -453,7 +453,8 @@ PLy_cursor_fetch(PyObject *self, PyObject *args)
{
PyObject *row = PLy_input_from_tuple(&cursor->result,
SPI_tuptable->vals[i],
SPI_tuptable->tupdesc);
SPI_tuptable->tupdesc,
true);
PyList_SetItem(ret->rows, i, row);
}

23
src/pl/plpython/plpy_exec.c
View File

@ -13,6 +13,7 @@
#include "executor/spi.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/typcache.h"
@ -751,6 +752,11 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
PyDict_SetItemString(pltdata, "level", pltlevel);
Py_DECREF(pltlevel);
/*
* Note: In BEFORE trigger, stored generated columns are not computed yet,
* so don't make them accessible in NEW row.
*/
if (TRIGGER_FIRED_BY_INSERT(tdata->tg_event))
{
pltevent = PyString_FromString("INSERT");
@ -758,7 +764,8 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
PyDict_SetItemString(pltdata, "old", Py_None);
pytnew = PLy_input_from_tuple(&proc->result_in,
tdata->tg_trigtuple,
rel_descr);
rel_descr,
!TRIGGER_FIRED_BEFORE(tdata->tg_event));
PyDict_SetItemString(pltdata, "new", pytnew);
Py_DECREF(pytnew);
*rv = tdata->tg_trigtuple;
@ -770,7 +777,8 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
PyDict_SetItemString(pltdata, "new", Py_None);
pytold = PLy_input_from_tuple(&proc->result_in,
tdata->tg_trigtuple,
rel_descr);
rel_descr,
true);
PyDict_SetItemString(pltdata, "old", pytold);
Py_DECREF(pytold);
*rv = tdata->tg_trigtuple;
@ -781,12 +789,14 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
pytnew = PLy_input_from_tuple(&proc->result_in,
tdata->tg_newtuple,
rel_descr);
rel_descr,
!TRIGGER_FIRED_BEFORE(tdata->tg_event));
PyDict_SetItemString(pltdata, "new", pytnew);
Py_DECREF(pytnew);
pytold = PLy_input_from_tuple(&proc->result_in,
tdata->tg_trigtuple,
rel_descr);
rel_descr,
true);
PyDict_SetItemString(pltdata, "old", pytold);
Py_DECREF(pytold);
*rv = tdata->tg_newtuple;
@ -952,6 +962,11 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot set system attribute \"%s\"",
plattstr)));
if (TupleDescAttr(tupdesc, attn - 1)->attgenerated)
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("cannot set generated column \"%s\"",
plattstr)));
plval = PyDict_GetItem(plntup, platt);
if (plval == NULL)

3
src/pl/plpython/plpy_spi.c
View File

@ -419,7 +419,8 @@ PLy_spi_execute_fetch_result(SPITupleTable *tuptable, uint64 rows, int status)
{
PyObject *row = PLy_input_from_tuple(&ininfo,
tuptable->vals[i],
tuptable->tupdesc);
tuptable->tupdesc,
true);
PyList_SetItem(result->rows, i, row);
}

17
src/pl/plpython/plpy_typeio.c
View File

@ -41,7 +41,7 @@ static PyObject *PLyList_FromArray(PLyDatumToOb *arg, Datum d);
static PyObject *PLyList_FromArray_recurse(PLyDatumToOb *elm, int *dims, int ndim, int dim,
char **dataptr_p, bits8 **bitmap_p, int *bitmask_p);
static PyObject *PLyDict_FromComposite(PLyDatumToOb *arg, Datum d);
static PyObject *PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc);
static PyObject *PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc, bool include_generated);
/* conversion from Python objects to Datums */
static Datum PLyObject_ToBool(PLyObToDatum *arg, PyObject *plrv,
@ -134,7 +134,7 @@ PLy_output_convert(PLyObToDatum *arg, PyObject *val, bool *isnull)
* but in practice all callers have the right tupdesc available.
*/
PyObject *
PLy_input_from_tuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc)
PLy_input_from_tuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc, bool include_generated)
{
PyObject *dict;
PLyExecutionContext *exec_ctx = PLy_current_execution_context();
@ -148,7 +148,7 @@ PLy_input_from_tuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc)
oldcontext = MemoryContextSwitchTo(scratch_context);
dict = PLyDict_FromTuple(arg, tuple, desc);
dict = PLyDict_FromTuple(arg, tuple, desc, include_generated);
MemoryContextSwitchTo(oldcontext);
@ -804,7 +804,7 @@ PLyDict_FromComposite(PLyDatumToOb *arg, Datum d)
tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
tmptup.t_data = td;
dict = PLyDict_FromTuple(arg, &tmptup, tupdesc);
dict = PLyDict_FromTuple(arg, &tmptup, tupdesc, true);
ReleaseTupleDesc(tupdesc);
@ -815,7 +815,7 @@ PLyDict_FromComposite(PLyDatumToOb *arg, Datum d)
* Transform a tuple into a Python dict object.
*/
static PyObject *
PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc)
PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc, bool include_generated)
{
PyObject *volatile dict;
@ -842,6 +842,13 @@ PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc)
if (attr->attisdropped)
continue;
if (attr->attgenerated)
{
/* don't include unless requested */
if (!include_generated)
continue;
}
key = NameStr(attr->attname);
vattr = heap_getattr(tuple, (i + 1), desc, &is_null);

2
src/pl/plpython/plpy_typeio.h
View File

@ -151,7 +151,7 @@ extern Datum PLy_output_convert(PLyObToDatum *arg, PyObject *val,
bool *isnull);
extern PyObject *PLy_input_from_tuple(PLyDatumToOb *arg, HeapTuple tuple,
TupleDesc desc);
TupleDesc desc, bool include_generated);
extern void PLy_input_setup_func(PLyDatumToOb *arg, MemoryContext arg_mcxt,
Oid typeOid, int32 typmod,

37
src/pl/plpython/sql/plpython_trigger.sql
View File

@ -67,6 +67,11 @@ SELECT * FROM users;
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 $$
if 'relid' in TD:
@ -109,6 +114,21 @@ DROP TRIGGER show_trigger_data_trig_stmt on trigger_test;
DROP TRIGGER show_trigger_data_trig_before on trigger_test;
DROP TRIGGER show_trigger_data_trig_after on trigger_test;
CREATE TRIGGER show_trigger_data_trig_before
BEFORE INSERT OR UPDATE OR DELETE ON trigger_test_generated
FOR EACH ROW EXECUTE PROCEDURE trigger_data();
CREATE TRIGGER show_trigger_data_trig_after
AFTER INSERT OR UPDATE OR DELETE ON trigger_test_generated
FOR EACH ROW EXECUTE PROCEDURE trigger_data();
insert into trigger_test_generated (i) values (1);
update trigger_test_generated set i = 11 where i = 1;
delete from trigger_test_generated;
DROP TRIGGER show_trigger_data_trig_before ON trigger_test_generated;
DROP TRIGGER show_trigger_data_trig_after ON trigger_test_generated;
insert into trigger_test values(1,'insert');
CREATE VIEW trigger_test_view AS SELECT * FROM trigger_test;
@ -430,3 +450,20 @@ UPDATE transition_table_test SET name = 'b';
DROP TABLE transition_table_test;
DROP FUNCTION transition_table_test_f();
-- dealing with generated columns
CREATE FUNCTION generated_test_func1() RETURNS trigger
LANGUAGE plpythonu
AS $$
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);
SELECT * FROM trigger_test_generated;