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Catch syntax error in generated column definition

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The syntax

    GENERATED BY DEFAULT AS (expr)

is not allowed but we have to accept it in the grammar to avoid
shift/reduce conflicts because of the similar syntax for identity
columns.  The existing code just ignored this, incorrectly.  Add an
explicit error check and a bespoke error message.

Reported-by: Justin Pryzby <pryzby@telsasoft.com>
This commit is contained in:
Peter Eisentraut
2019-04-01 10:46:37 +02:00
parent 4ae7f02b03
commit 7241911782
3 changed files with 21 additions and 0 deletions
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13
src/backend/parser/gram.y
View File

@ -3505,6 +3505,19 @@ ColConstraintElem:
n->raw_expr = $5; n->raw_expr = $5;
n->cooked_expr = NULL; n->cooked_expr = NULL;
n->location = @1; n->location = @1;
/*
* Can't do this in the grammar because of shift/reduce
* conflicts. (IDENTITY allows both ALWAYS and BY
* DEFAULT, but generated columns only allow ALWAYS.) We
* can also give a more useful error message and location.
*/
if ($2 != ATTRIBUTE_IDENTITY_ALWAYS)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("for a generated column, GENERATED ALWAYS must be specified"),
parser_errposition(@2)));
$$ = (Node *)n; $$ = (Node *)n;
} }
| REFERENCES qualified_name opt_column_list key_match key_actions | REFERENCES qualified_name opt_column_list key_match key_actions

5
src/test/regress/expected/generated.out
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@ -85,6 +85,11 @@ CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generat
ERROR: set-returning functions are not allowed in column generation expressions ERROR: set-returning functions are not allowed in column generation expressions
LINE 1: ...7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_s... LINE 1: ...7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_s...
^ ^
-- GENERATED BY DEFAULT not allowed
CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) STORED);
ERROR: for a generated column, GENERATED ALWAYS must be specified
LINE 1: ...E gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT...
^
INSERT INTO gtest1 VALUES (1); INSERT INTO gtest1 VALUES (1);
INSERT INTO gtest1 VALUES (2, DEFAULT); INSERT INTO gtest1 VALUES (2, DEFAULT);
INSERT INTO gtest1 VALUES (3, 33); -- error INSERT INTO gtest1 VALUES (3, 33); -- error

3
src/test/regress/sql/generated.sql
View File

@ -37,6 +37,9 @@ CREATE TABLE gtest_err_7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_num
CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) STORED); CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) STORED);
CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) STORED); CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) STORED);
-- GENERATED BY DEFAULT not allowed
CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) STORED);
INSERT INTO gtest1 VALUES (1); INSERT INTO gtest1 VALUES (1);
INSERT INTO gtest1 VALUES (2, DEFAULT); INSERT INTO gtest1 VALUES (2, DEFAULT);
INSERT INTO gtest1 VALUES (3, 33); -- error INSERT INTO gtest1 VALUES (3, 33); -- error