From 4ea775e87bf485239518172a7445cc2b24795511 Mon Sep 17 00:00:00 2001 From: "Paul A. Jungwirth" Date: Thu, 14 May 2026 09:56:24 -0700 Subject: [PATCH v4] Forbid GENERATED columns in FOR PORTION OF With VIRTUAL columns there is no column to assign to, and we shouldn't assign directly to STORED columns either. (Once we have PERIODs, we will allow a STORED column here, but we will assign to its start/end inputs.) It is safe to do this check in parse analysis, because an ordinary column cannot be converted to a GENERATED column later. Technically columns with integer types can be converted to identity columns, but those can't be used in FOR PORTION OF. Even BEGIN ATOMIC SQL functions, which parse the statement far in advance of executing it, are safe. Discussion: https://www.postgresql.org/message-id/agOOykf2HV26yVfU%40nathan --- src/backend/parser/analyze.c | 14 ++++ src/test/regress/expected/for_portion_of.out | 67 ++++++++++++++++++++ src/test/regress/sql/for_portion_of.sql | 46 ++++++++++++++ 3 files changed, 127 insertions(+) diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c index 93fa66ae57c..69f84c5f3d8 100644 --- a/src/backend/parser/analyze.c +++ b/src/backend/parser/analyze.c @@ -1354,6 +1354,20 @@ transformForPortionOfClause(ParseState *pstate, parser_errposition(pstate, forPortionOf->location))); attr = TupleDescAttr(targetrel->rd_att, range_attno - 1); + /* + * Reject generated columns. We can't write to a virtual generated column, + * and a stored generated column should be written by its own expression. + * + * XXX: We plan to implement PERIODs as stored generated columns, so later + * we will loosen this restriction if the column belongs to a PERIOD. + */ + if (attr->attgenerated) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot use generated column \"%s\" in FOR PORTION OF", + forPortionOf->range_name), + parser_errposition(pstate, forPortionOf->location))); + attbasetype = getBaseType(attr->atttypid); rangeVar = makeVar(rtindex, diff --git a/src/test/regress/expected/for_portion_of.out b/src/test/regress/expected/for_portion_of.out index 43408972117..86ec7381e4b 100644 --- a/src/test/regress/expected/for_portion_of.out +++ b/src/test/regress/expected/for_portion_of.out @@ -2208,6 +2208,73 @@ SELECT * FROM fpo_rule ORDER BY f1; (2 rows) DROP TABLE fpo_rule; +-- UPDATE/DELETE FOR PORTION OF on a GENERATED VIRTUAL range column: +CREATE TABLE fpo_gen_virtual ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) VIRTUAL +); +INSERT INTO fpo_gen_virtual VALUES (1); +DELETE FROM fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2; -- fails +ERROR: cannot use generated column "b" in FOR PORTION OF +LINE 1: DELETE FROM fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2; + ^ +UPDATE fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2 SET a = 5; -- fails +ERROR: cannot use generated column "b" in FOR PORTION OF +LINE 1: UPDATE fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2 SET a = ... + ^ +DROP TABLE fpo_gen_virtual; +-- UPDATE/DELETE FOR PORTION OF on a GENERATED STORED range column: +CREATE TABLE fpo_gen_stored ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) STORED +); +INSERT INTO fpo_gen_stored VALUES (1); +DELETE FROM fpo_gen_stored FOR PORTION OF b FROM 1 TO 2; -- fails +ERROR: cannot use generated column "b" in FOR PORTION OF +LINE 1: DELETE FROM fpo_gen_stored FOR PORTION OF b FROM 1 TO 2; + ^ +UPDATE fpo_gen_stored FOR PORTION OF b FROM 1 TO 2 SET a = 5; -- fails +ERROR: cannot use generated column "b" in FOR PORTION OF +LINE 1: UPDATE fpo_gen_stored FOR PORTION OF b FROM 1 TO 2 SET a = 5... + ^ +DROP TABLE fpo_gen_stored; +-- A new-style SQL function is parsed at CREATE FUNCTION time, but our +-- generated-column check is in the executor, so it sees the column's +-- current attgenerated when the function actually runs. +CREATE TABLE fpo_func_test ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) STORED +); +INSERT INTO fpo_func_test VALUES (1); +-- Definition fails because b is a generated column. +CREATE FUNCTION fpo_delete() RETURNS void + LANGUAGE SQL + BEGIN ATOMIC + DELETE FROM fpo_func_test FOR PORTION OF b FROM 1 TO 2; + END; +ERROR: cannot use generated column "b" in FOR PORTION OF +LINE 4: DELETE FROM fpo_func_test FOR PORTION OF b FROM 1 TO 2; + ^ +-- Drop the generation expression and the same function now succeeds. +ALTER TABLE fpo_func_test ALTER COLUMN b DROP EXPRESSION; +CREATE FUNCTION fpo_delete() RETURNS void + LANGUAGE SQL + BEGIN ATOMIC + DELETE FROM fpo_func_test FOR PORTION OF b FROM 1 TO 2; + END; +SELECT fpo_delete(); + fpo_delete +------------ + +(1 row) + +TABLE fpo_func_test ORDER BY a, b; + a | b +---+--- +(0 rows) + +DROP FUNCTION fpo_delete(); +DROP TABLE fpo_func_test; -- UPDATE/DELETE FOR PORTION OF with table inheritance -- Leftover rows must stay in the child table, preserving child-specific columns. CREATE TABLE fpo_inh_parent ( diff --git a/src/test/regress/sql/for_portion_of.sql b/src/test/regress/sql/for_portion_of.sql index 7b08f8cf45e..676fa4814ce 100644 --- a/src/test/regress/sql/for_portion_of.sql +++ b/src/test/regress/sql/for_portion_of.sql @@ -1448,6 +1448,52 @@ SELECT * FROM fpo_rule ORDER BY f1; DROP TABLE fpo_rule; +-- UPDATE/DELETE FOR PORTION OF on a GENERATED VIRTUAL range column: +CREATE TABLE fpo_gen_virtual ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) VIRTUAL +); +INSERT INTO fpo_gen_virtual VALUES (1); +DELETE FROM fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2; -- fails +UPDATE fpo_gen_virtual FOR PORTION OF b FROM 1 TO 2 SET a = 5; -- fails +DROP TABLE fpo_gen_virtual; + +-- UPDATE/DELETE FOR PORTION OF on a GENERATED STORED range column: +CREATE TABLE fpo_gen_stored ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) STORED +); +INSERT INTO fpo_gen_stored VALUES (1); +DELETE FROM fpo_gen_stored FOR PORTION OF b FROM 1 TO 2; -- fails +UPDATE fpo_gen_stored FOR PORTION OF b FROM 1 TO 2 SET a = 5; -- fails +DROP TABLE fpo_gen_stored; + +-- A new-style SQL function is parsed at CREATE FUNCTION time, but our +-- generated-column check is in the executor, so it sees the column's +-- current attgenerated when the function actually runs. +CREATE TABLE fpo_func_test ( + a int, + b int4range GENERATED ALWAYS AS (int4range(a, a + 1)) STORED +); +INSERT INTO fpo_func_test VALUES (1); +-- Definition fails because b is a generated column. +CREATE FUNCTION fpo_delete() RETURNS void + LANGUAGE SQL + BEGIN ATOMIC + DELETE FROM fpo_func_test FOR PORTION OF b FROM 1 TO 2; + END; +-- Drop the generation expression and the same function now succeeds. +ALTER TABLE fpo_func_test ALTER COLUMN b DROP EXPRESSION; +CREATE FUNCTION fpo_delete() RETURNS void + LANGUAGE SQL + BEGIN ATOMIC + DELETE FROM fpo_func_test FOR PORTION OF b FROM 1 TO 2; + END; +SELECT fpo_delete(); +TABLE fpo_func_test ORDER BY a, b; +DROP FUNCTION fpo_delete(); +DROP TABLE fpo_func_test; + -- UPDATE/DELETE FOR PORTION OF with table inheritance -- Leftover rows must stay in the child table, preserving child-specific columns. CREATE TABLE fpo_inh_parent ( -- 2.47.3