Forbid marking an identity column as nullable.

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

diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 3b2b227683a2fe2854b36370512ac5ceb96f1c50..71703da85aef30db5198cf67e86e26dbcd7c5671 100644 (file)
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -840,6 +840,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       column</firstterm>.  It will have an implicit sequence attached to it
       and the column in new rows will automatically have values from the
       sequence assigned to it.
+      Such a column is implicitly <literal>NOT NULL</literal>.
      </para>
 
      <para>

diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 75266caeb4bb50a635a3572c3fde0a3719516702..d56f81c79ff09ced9e11cfe26b6639b55ebaeab6 100644 (file)
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -719,7 +719,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
                    column->identity = constraint->generated_when;
                    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;
+                   saw_nullable = true;
                    break;
                }
 

diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
index fbca0333a2c85ab87d2a145741bc5cefb0665b38..99811570b7bf35fc40474cf7a856efb3ff752bac 100644 (file)
--- a/src/test/regress/expected/identity.out
+++ b/src/test/regress/expected/identity.out
@@ -547,3 +547,16 @@ CREATE TABLE itest14 (id serial);
 ALTER TABLE itest14 ALTER id DROP DEFAULT;
 ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
 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;

diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
index cdda186720df1b281cc63b03fda008746a74eebf..52800f265c2765ab35c8314f425a8c1cbb7df367 100644 (file)
--- a/src/test/regress/sql/identity.sql
+++ b/src/test/regress/sql/identity.sql
@@ -346,3 +346,12 @@ CREATE TABLE itest14 (id serial);
 ALTER TABLE itest14 ALTER id DROP DEFAULT;
 ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
 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;