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Fix ALTER TABLE ADD VIRTUAL GENERATED COLUMN when table rewrite

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demo:
CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT RANDOM() CHECK (b < 60);
ERROR:  no generation expression found for column number 2 of table "pg_temp_17306"

In ATRewriteTable, the variable OIDNewHeap (if valid) corresponding
pg_attrdef default expression entry was not populated.  So OIDNewHeap
cannot be used to call expand_generated_columns_in_expr or
build_generation_expression.  Therefore in ATRewriteTable, we can only
use the existing relation to expand the generated expression.

Author: jian he <jian.universality@gmail.com>
Reviewed-by: Srinath Reddy <srinath2133@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CACJufxEJ%3DFoajabWXjszo_yrQeKSxdZ87KJqBW373rSbajKGAA%40mail.gmail.com
This commit is contained in:
Peter Eisentraut
2025-03-04 09:18:32 +01:00
parent 716a051aac
commit f011acdd61
5 changed files with 15 additions and 1 deletions
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2
src/backend/commands/tablecmds.c
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@ -6137,7 +6137,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap)
{ {
case CONSTR_CHECK: case CONSTR_CHECK:
needscan = true; needscan = true;
con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, newrel ? newrel : oldrel, 1), estate); con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate);
break; break;
case CONSTR_FOREIGN: case CONSTR_FOREIGN:
/* Nothing to do here */ /* Nothing to do here */

4
src/test/regress/expected/generated_stored.out
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@ -656,6 +656,10 @@ INSERT INTO gtest20a (a) VALUES (10);
INSERT INTO gtest20a (a) VALUES (30); INSERT INTO gtest20a (a) VALUES (30);
ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row
ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row
-- table rewrite cases
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 50); -- fails on existing row
ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 61); -- ok
CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED); CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
INSERT INTO gtest20b (a) VALUES (10); INSERT INTO gtest20b (a) VALUES (10);
INSERT INTO gtest20b (a) VALUES (30); INSERT INTO gtest20b (a) VALUES (30);

4
src/test/regress/expected/generated_virtual.out
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@ -647,6 +647,10 @@ INSERT INTO gtest20a (a) VALUES (10);
INSERT INTO gtest20a (a) VALUES (30); INSERT INTO gtest20a (a) VALUES (30);
ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row
ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row
-- table rewrite cases
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 50); -- fails on existing row
ERROR: check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 61); -- ok
CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL); CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
INSERT INTO gtest20b (a) VALUES (10); INSERT INTO gtest20b (a) VALUES (10);
INSERT INTO gtest20b (a) VALUES (30); INSERT INTO gtest20b (a) VALUES (30);

3
src/test/regress/sql/generated_stored.sql
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@ -319,6 +319,9 @@ CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STOR
INSERT INTO gtest20a (a) VALUES (10); INSERT INTO gtest20a (a) VALUES (10);
INSERT INTO gtest20a (a) VALUES (30); INSERT INTO gtest20a (a) VALUES (30);
ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row
-- table rewrite cases
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 50); -- fails on existing row
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 61); -- ok
CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED); CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
INSERT INTO gtest20b (a) VALUES (10); INSERT INTO gtest20b (a) VALUES (10);

3
src/test/regress/sql/generated_virtual.sql
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@ -319,6 +319,9 @@ CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRT
INSERT INTO gtest20a (a) VALUES (10); INSERT INTO gtest20a (a) VALUES (10);
INSERT INTO gtest20a (a) VALUES (30); INSERT INTO gtest20a (a) VALUES (30);
ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row ALTER TABLE gtest20a ADD CHECK (b < 50); -- fails on existing row
-- table rewrite cases
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 50); -- fails on existing row
ALTER TABLE gtest20a ADD COLUMN c float8 DEFAULT random() CHECK (b < 61); -- ok
CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL); CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
INSERT INTO gtest20b (a) VALUES (10); INSERT INTO gtest20b (a) VALUES (10);