Postgres dialect: Fix parse error for "on delete", "on update" clause…

…s in column constraints (#1586)

* Issue #1554: Postgres dialect: Parse error for "on delete" in column constraint

* Fix for UPDATE keyword and update tests

Co-authored-by: Alan Cruickshank <alanmcruickshank@gmail.com>
Co-authored-by: Barry Pollard <barry@tunetheweb.com>

src/sqlfluff/dialects/dialect_postgres.py

@@ -1029,6 +1029,12 @@ class ColumnConstraintSegment(BaseSegment):
                 Ref("ColumnReferenceSegment"),
                 # Foreign columns making up FOREIGN KEY constraint
                 Ref("BracketedColumnReferenceListGrammar", optional=True),
+                Sequence(
+                    "ON",
+                    OneOf("DELETE", "UPDATE"),
+                    Ref("ReferentialActionSegment"),
+                    optional=True,
+                ),
             ),
         ),
         OneOf("DEFERRABLE", Sequence("NOT", "DEFERRABLE"), optional=True),

test/fixtures/parser/postgres/postgres_create_table.sql

@@ -212,3 +212,13 @@ operation_id int4 NOT NULL DEFAULT '-1'::integer
 CREATE TABLE main.test_table (
     "col1" character varying(40) NOT NULL
 );
+
+CREATE TABLE groups (
+    group_id INTEGER PRIMARY KEY generated BY DEFAULT AS IDENTITY
+);
+
+CREATE TABLE users (
+    user_id INTEGER PRIMARY KEY generated BY DEFAULT AS IDENTITY,
+    group_id INTEGER REFERENCES groups (group_id) ON DELETE CASCADE,
+    domain_id INTEGER REFERENCES groups (group_id) ON UPDATE RESTRICT
+);

test/fixtures/parser/postgres/postgres_create_table.yml

@@ -3,7 +3,7 @@
 # computed by SQLFluff when running the tests. Please run
 # `python test/generate_parse_fixture_yml.py`  to generate them after adding or
 # altering SQL files.
-_hash: 0ef79bbd602bc4202e929d6764458043407d864a13ed41260627d3ad66420b22
+_hash: 463feff7c6b4deebbfc0bdd82d953eb4544d40a5e359724a4c64a6631ad6c37a
 file:
 - statement:
     create_table_statement:
@@ -1233,3 +1233,85 @@ file:
         - keyword: 'NULL'
         end_bracket: )
 - statement_terminator: ;
+- statement:
+    create_table_statement:
+    - keyword: CREATE
+    - keyword: TABLE
+    - table_reference:
+        identifier: groups
+    - bracketed:
+      - start_bracket: (
+      - column_reference:
+          identifier: group_id
+      - data_type:
+          data_type_identifier: INTEGER
+      - column_constraint_segment:
+        - keyword: PRIMARY
+        - keyword: KEY
+      - column_constraint_segment:
+        - keyword: generated
+        - keyword: BY
+        - keyword: DEFAULT
+        - keyword: AS
+        - keyword: IDENTITY
+      - end_bracket: )
+- statement_terminator: ;
+- statement:
+    create_table_statement:
+    - keyword: CREATE
+    - keyword: TABLE
+    - table_reference:
+        identifier: users
+    - bracketed:
+      - start_bracket: (
+      - column_reference:
+          identifier: user_id
+      - data_type:
+          data_type_identifier: INTEGER
+      - column_constraint_segment:
+        - keyword: PRIMARY
+        - keyword: KEY
+      - column_constraint_segment:
+        - keyword: generated
+        - keyword: BY
+        - keyword: DEFAULT
+        - keyword: AS
+        - keyword: IDENTITY
+      - comma: ','
+      - column_reference:
+          identifier: group_id
+      - data_type:
+          data_type_identifier: INTEGER
+      - column_constraint_segment:
+        - keyword: REFERENCES
+        - column_reference:
+            identifier: groups
+        - bracketed:
+            start_bracket: (
+            column_reference:
+              identifier: group_id
+            end_bracket: )
+        - keyword: 'ON'
+        - keyword: DELETE
+        - referential_action:
+            keyword: CASCADE
+      - comma: ','
+      - column_reference:
+          identifier: domain_id
+      - data_type:
+          data_type_identifier: INTEGER
+      - column_constraint_segment:
+        - keyword: REFERENCES
+        - column_reference:
+            identifier: groups
+        - bracketed:
+            start_bracket: (
+            column_reference:
+              identifier: group_id
+            end_bracket: )
+        - keyword: 'ON'
+        - keyword: UPDATE
+        - referential_action:
+            keyword: RESTRICT
+      - end_bracket: )
+- statement_terminator: ;