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Forbid marking an identity column as nullable.

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GENERATED ALWAYS AS IDENTITY implies NOT NULL, but the code failed
to complain if you overrode that with "GENERATED ALWAYS AS IDENTITY
NULL".  One might think the old behavior was a feature, but it was
inconsistent because the outcome varied depending on the order of
the clauses, so it seems to have been just an oversight.

Per bug #16913 from Pavel Boev.  Back-patch to v10 where identity
columns were introduced.

Vik Fearing (minor tweaks by me)

Discussion: https://postgr.es/m/16913-3b5198410f67d8c6@postgresql.org
This commit is contained in:
Tom Lane 2021-03-12 11:08:42 -05:00
parent 1b88b8908e
commit f52c5d6749
4 changed files with 33 additions and 0 deletions
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1
doc/src/sgml/ref/create_table.sgml
View File

@ -840,6 +840,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
column</firstterm>. It will have an implicit sequence attached to it column</firstterm>. It will have an implicit sequence attached to it
and the column in new rows will automatically have values from the and the column in new rows will automatically have values from the
sequence assigned to it. sequence assigned to it.
Such a column is implicitly <literal>NOT NULL</literal>.
</para> </para>
<para> <para>

10
src/backend/parser/parse_utilcmd.c
View File

@ -719,7 +719,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
column->identity = constraint->generated_when; column->identity = constraint->generated_when;
saw_identity = true; saw_identity = true;
/* An identity column is implicitly NOT NULL */
if (saw_nullable && !column->is_not_null)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
column->colname, cxt->relation->relname),
parser_errposition(cxt->pstate,
constraint->location)));
column->is_not_null = true; column->is_not_null = true;
saw_nullable = true;
break; break;
} }

13
src/test/regress/expected/identity.out
View File

@ -547,3 +547,16 @@ CREATE TABLE itest14 (id serial);
ALTER TABLE itest14 ALTER id DROP DEFAULT; ALTER TABLE itest14 ALTER id DROP DEFAULT;
ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY; ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
INSERT INTO itest14 (id) VALUES (DEFAULT); INSERT INTO itest14 (id) VALUES (DEFAULT);
-- Identity columns must be NOT NULL (cf bug #16913)
CREATE TABLE itest15 (id integer GENERATED ALWAYS AS IDENTITY NULL); -- fail
ERROR: conflicting NULL/NOT NULL declarations for column "id" of table "itest15"
LINE 1: ...ABLE itest15 (id integer GENERATED ALWAYS AS IDENTITY NULL);
^
CREATE TABLE itest15 (id integer NULL GENERATED ALWAYS AS IDENTITY); -- fail
ERROR: conflicting NULL/NOT NULL declarations for column "id" of table "itest15"
LINE 1: CREATE TABLE itest15 (id integer NULL GENERATED ALWAYS AS ID...
^
CREATE TABLE itest15 (id integer GENERATED ALWAYS AS IDENTITY NOT NULL);
DROP TABLE itest15;
CREATE TABLE itest15 (id integer NOT NULL GENERATED ALWAYS AS IDENTITY);
DROP TABLE itest15;

9
src/test/regress/sql/identity.sql
View File

@ -346,3 +346,12 @@ CREATE TABLE itest14 (id serial);
ALTER TABLE itest14 ALTER id DROP DEFAULT; ALTER TABLE itest14 ALTER id DROP DEFAULT;
ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY; ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
INSERT INTO itest14 (id) VALUES (DEFAULT); INSERT INTO itest14 (id) VALUES (DEFAULT);
-- Identity columns must be NOT NULL (cf bug #16913)
CREATE TABLE itest15 (id integer GENERATED ALWAYS AS IDENTITY NULL); -- fail
CREATE TABLE itest15 (id integer NULL GENERATED ALWAYS AS IDENTITY); -- fail
CREATE TABLE itest15 (id integer GENERATED ALWAYS AS IDENTITY NOT NULL);
DROP TABLE itest15;
CREATE TABLE itest15 (id integer NOT NULL GENERATED ALWAYS AS IDENTITY);
DROP TABLE itest15;