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Add support of COMMENT ON syntax for Snowflake
The COMMENT ON syntax has been supported in PostgreSQL. This PR only moves it into the common and adds `supports_comment_on` to enable this feature. Also, this PR extends `SCHEMA`, `DATABASE`, `USER`, `ROLE` as its allowed object type. This closes #1511.
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8 files changed

+166
-102
lines changed

8 files changed

+166
-102
lines changed

‎src/ast/mod.rs

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1884,6 +1884,10 @@ pub enum CommentObject {
18841884
Column,
18851885
Table,
18861886
Extension,
1887+
Schema,
1888+
Database,
1889+
User,
1890+
Role,
18871891
}
18881892

18891893
impl fmt::Display for CommentObject {
@@ -1892,6 +1896,10 @@ impl fmt::Display for CommentObject {
18921896
CommentObject::Column => f.write_str("COLUMN"),
18931897
CommentObject::Table => f.write_str("TABLE"),
18941898
CommentObject::Extension => f.write_str("EXTENSION"),
1899+
CommentObject::Schema => f.write_str("SCHEMA"),
1900+
CommentObject::Database => f.write_str("DATABASE"),
1901+
CommentObject::User => f.write_str("USER"),
1902+
CommentObject::Role => f.write_str("ROLE"),
18951903
}
18961904
}
18971905
}

‎src/dialect/generic.rs

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -111,4 +111,8 @@ impl Dialect for GenericDialect {
111111
fn supports_try_convert(&self) -> bool {
112112
true
113113
}
114+
115+
fn supports_comment_on(&self) -> bool {
116+
true
117+
}
114118
}

‎src/dialect/mod.rs

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -601,11 +601,16 @@ pub trait Dialect: Debug + Any {
601601
false
602602
}
603603

604-
/// Returns true if this dialect expects the the `TOP` option
604+
/// Returns true if this dialect expects the `TOP` option
605605
/// before the `ALL`/`DISTINCT` options in a `SELECT` statement.
606606
fn supports_top_before_distinct(&self) -> bool {
607607
false
608608
}
609+
610+
/// Returns true if this dialect supports the `COMMENT` statement
611+
fn supports_comment_on(&self) -> bool {
612+
false
613+
}
609614
}
610615

611616
/// This represents the operators for which precedence must be defined

‎src/dialect/postgresql.rs

Lines changed: 6 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -28,7 +28,7 @@
2828
// limitations under the License.
2929
use log::debug;
3030

31-
use crate::ast::{CommentObject, ObjectName, Statement, UserDefinedTypeRepresentation};
31+
use crate::ast::{ObjectName, Statement, UserDefinedTypeRepresentation};
3232
use crate::dialect::{Dialect, Precedence};
3333
use crate::keywords::Keyword;
3434
use crate::parser::{Parser, ParserError};
@@ -136,9 +136,7 @@ impl Dialect for PostgreSqlDialect {
136136
}
137137

138138
fn parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
139-
if parser.parse_keyword(Keyword::COMMENT) {
140-
Some(parse_comment(parser))
141-
} else if parser.parse_keyword(Keyword::CREATE) {
139+
if parser.parse_keyword(Keyword::CREATE) {
142140
parser.prev_token(); // unconsume the CREATE in case we don't end up parsing anything
143141
parse_create(parser)
144142
} else {
@@ -201,42 +199,11 @@ impl Dialect for PostgreSqlDialect {
201199
fn supports_notify(&self) -> bool {
202200
true
203201
}
204-
}
205-
206-
pub fn parse_comment(parser: &mut Parser) -> Result<Statement, ParserError> {
207-
let if_exists = parser.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
208-
209-
parser.expect_keyword(Keyword::ON)?;
210-
let token = parser.next_token();
211-
212-
let (object_type, object_name) = match token.token {
213-
Token::Word(w) if w.keyword == Keyword::COLUMN => {
214-
let object_name = parser.parse_object_name(false)?;
215-
(CommentObject::Column, object_name)
216-
}
217-
Token::Word(w) if w.keyword == Keyword::TABLE => {
218-
let object_name = parser.parse_object_name(false)?;
219-
(CommentObject::Table, object_name)
220-
}
221-
Token::Word(w) if w.keyword == Keyword::EXTENSION => {
222-
let object_name = parser.parse_object_name(false)?;
223-
(CommentObject::Extension, object_name)
224-
}
225-
_ => parser.expected("comment object_type", token)?,
226-
};
227202

228-
parser.expect_keyword(Keyword::IS)?;
229-
let comment = if parser.parse_keyword(Keyword::NULL) {
230-
None
231-
} else {
232-
Some(parser.parse_literal_string()?)
233-
};
234-
Ok(Statement::Comment {
235-
object_type,
236-
object_name,
237-
comment,
238-
if_exists,
239-
})
203+
/// see <https://www.postgresql.org/docs/current/sql-comment.html>
204+
fn supports_comment_on(&self) -> bool {
205+
true
206+
}
240207
}
241208

242209
pub fn parse_create(parser: &mut Parser) -> Option<Result<Statement, ParserError>> {

‎src/dialect/snowflake.rs

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -96,6 +96,11 @@ impl Dialect for SnowflakeDialect {
9696
true
9797
}
9898

99+
/// See [doc](https://docs.snowflake.com/en/sql-reference/sql/comment)
100+
fn supports_comment_on(&self) -> bool {
101+
true
102+
}
103+
99104
fn parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
100105
if parser.parse_keyword(Keyword::CREATE) {
101106
// possibly CREATE STAGE

‎src/parser/mod.rs

Lines changed: 49 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -551,6 +551,10 @@ impl<'a> Parser<'a> {
551551
Keyword::OPTIMIZE if dialect_of!(self is ClickHouseDialect | GenericDialect) => {
552552
self.parse_optimize_table()
553553
}
554+
// `COMMENT` is snowflake specific https://docs.snowflake.com/en/sql-reference/sql/comment
555+
Keyword::COMMENT if self.dialect.supports_comment_on() => {
556+
self.parse_comment()
557+
}
554558
_ => self.expected("an SQL statement", next_token),
555559
},
556560
Token::LParen => {
@@ -561,6 +565,51 @@ impl<'a> Parser<'a> {
561565
}
562566
}
563567

568+
pub fn parse_comment(&mut self) -> Result<Statement, ParserError> {
569+
let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
570+
571+
self.expect_keyword(Keyword::ON)?;
572+
let token = self.next_token();
573+
574+
let (object_type, object_name) = match token.token {
575+
Token::Word(w) if w.keyword == Keyword::COLUMN => {
576+
(CommentObject::Column, self.parse_object_name(false)?)
577+
}
578+
Token::Word(w) if w.keyword == Keyword::TABLE => {
579+
(CommentObject::Table, self.parse_object_name(false)?)
580+
}
581+
Token::Word(w) if w.keyword == Keyword::EXTENSION => {
582+
(CommentObject::Extension, self.parse_object_name(false)?)
583+
}
584+
Token::Word(w) if w.keyword == Keyword::SCHEMA => {
585+
(CommentObject::Schema, self.parse_object_name(false)?)
586+
}
587+
Token::Word(w) if w.keyword == Keyword::DATABASE => {
588+
(CommentObject::Database, self.parse_object_name(false)?)
589+
}
590+
Token::Word(w) if w.keyword == Keyword::USER => {
591+
(CommentObject::User, self.parse_object_name(false)?)
592+
}
593+
Token::Word(w) if w.keyword == Keyword::ROLE => {
594+
(CommentObject::Role, self.parse_object_name(false)?)
595+
}
596+
_ => self.expected("comment object_type", token)?,
597+
};
598+
599+
self.expect_keyword(Keyword::IS)?;
600+
let comment = if self.parse_keyword(Keyword::NULL) {
601+
None
602+
} else {
603+
Some(self.parse_literal_string()?)
604+
};
605+
Ok(Statement::Comment {
606+
object_type,
607+
object_name,
608+
comment,
609+
if_exists,
610+
})
611+
}
612+
564613
pub fn parse_flush(&mut self) -> Result<Statement, ParserError> {
565614
let mut channel = None;
566615
let mut tables: Vec<ObjectName> = vec![];

‎tests/sqlparser_common.rs

Lines changed: 88 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11532,3 +11532,91 @@ fn test_select_top() {
1153211532
dialects.verified_stmt("SELECT TOP 3 DISTINCT * FROM tbl");
1153311533
dialects.verified_stmt("SELECT TOP 3 DISTINCT a, b, c FROM tbl");
1153411534
}
11535+
11536+
#[test]
11537+
fn parse_comments() {
11538+
match all_dialects_where(|d| d.supports_comment_on())
11539+
.verified_stmt("COMMENT ON COLUMN tab.name IS 'comment'")
11540+
{
11541+
Statement::Comment {
11542+
object_type,
11543+
object_name,
11544+
comment: Some(comment),
11545+
if_exists,
11546+
} => {
11547+
assert_eq!("comment", comment);
11548+
assert_eq!("tab.name", object_name.to_string());
11549+
assert_eq!(CommentObject::Column, object_type);
11550+
assert!(!if_exists);
11551+
}
11552+
_ => unreachable!(),
11553+
}
11554+
11555+
let object_types = [
11556+
("COLUMN", CommentObject::Column),
11557+
("EXTENSION", CommentObject::Extension),
11558+
("TABLE", CommentObject::Table),
11559+
("SCHEMA", CommentObject::Schema),
11560+
("DATABASE", CommentObject::Database),
11561+
("USER", CommentObject::User),
11562+
("ROLE", CommentObject::Role),
11563+
];
11564+
for (keyword, expected_object_type) in object_types.iter() {
11565+
match all_dialects_where(|d| d.supports_comment_on())
11566+
.verified_stmt(format!("COMMENT IF EXISTS ON {keyword} db.t0 IS 'comment'").as_str())
11567+
{
11568+
Statement::Comment {
11569+
object_type,
11570+
object_name,
11571+
comment: Some(comment),
11572+
if_exists,
11573+
} => {
11574+
assert_eq!("comment", comment);
11575+
assert_eq!("db.t0", object_name.to_string());
11576+
assert_eq!(*expected_object_type, object_type);
11577+
assert!(if_exists);
11578+
}
11579+
_ => unreachable!(),
11580+
}
11581+
}
11582+
11583+
match all_dialects_where(|d| d.supports_comment_on())
11584+
.verified_stmt("COMMENT IF EXISTS ON TABLE public.tab IS NULL")
11585+
{
11586+
Statement::Comment {
11587+
object_type,
11588+
object_name,
11589+
comment: None,
11590+
if_exists,
11591+
} => {
11592+
assert_eq!("public.tab", object_name.to_string());
11593+
assert_eq!(CommentObject::Table, object_type);
11594+
assert!(if_exists);
11595+
}
11596+
_ => unreachable!(),
11597+
}
11598+
11599+
// missing IS statement
11600+
assert_eq!(
11601+
all_dialects_where(|d| d.supports_comment_on())
11602+
.parse_sql_statements("COMMENT ON TABLE t0")
11603+
.unwrap_err(),
11604+
ParserError::ParserError("Expected: IS, found: EOF".to_string())
11605+
);
11606+
11607+
// missing comment literal
11608+
assert_eq!(
11609+
all_dialects_where(|d| d.supports_comment_on())
11610+
.parse_sql_statements("COMMENT ON TABLE t0 IS")
11611+
.unwrap_err(),
11612+
ParserError::ParserError("Expected: literal string, found: EOF".to_string())
11613+
);
11614+
11615+
// unknown object type
11616+
assert_eq!(
11617+
all_dialects_where(|d| d.supports_comment_on())
11618+
.parse_sql_statements("COMMENT ON UNKNOWN t0 IS 'comment'")
11619+
.unwrap_err(),
11620+
ParserError::ParserError("Expected: comment object_type, found: UNKNOWN".to_string())
11621+
);
11622+
}

‎tests/sqlparser_postgres.rs

Lines changed: 0 additions & 62 deletions
Original file line numberDiff line numberDiff line change
@@ -2891,68 +2891,6 @@ fn test_composite_value() {
28912891
);
28922892
}
28932893

2894-
#[test]
2895-
fn parse_comments() {
2896-
match pg().verified_stmt("COMMENT ON COLUMN tab.name IS 'comment'") {
2897-
Statement::Comment {
2898-
object_type,
2899-
object_name,
2900-
comment: Some(comment),
2901-
if_exists,
2902-
} => {
2903-
assert_eq!("comment", comment);
2904-
assert_eq!("tab.name", object_name.to_string());
2905-
assert_eq!(CommentObject::Column, object_type);
2906-
assert!(!if_exists);
2907-
}
2908-
_ => unreachable!(),
2909-
}
2910-
2911-
match pg().verified_stmt("COMMENT ON EXTENSION plpgsql IS 'comment'") {
2912-
Statement::Comment {
2913-
object_type,
2914-
object_name,
2915-
comment: Some(comment),
2916-
if_exists,
2917-
} => {
2918-
assert_eq!("comment", comment);
2919-
assert_eq!("plpgsql", object_name.to_string());
2920-
assert_eq!(CommentObject::Extension, object_type);
2921-
assert!(!if_exists);
2922-
}
2923-
_ => unreachable!(),
2924-
}
2925-
2926-
match pg().verified_stmt("COMMENT ON TABLE public.tab IS 'comment'") {
2927-
Statement::Comment {
2928-
object_type,
2929-
object_name,
2930-
comment: Some(comment),
2931-
if_exists,
2932-
} => {
2933-
assert_eq!("comment", comment);
2934-
assert_eq!("public.tab", object_name.to_string());
2935-
assert_eq!(CommentObject::Table, object_type);
2936-
assert!(!if_exists);
2937-
}
2938-
_ => unreachable!(),
2939-
}
2940-
2941-
match pg().verified_stmt("COMMENT IF EXISTS ON TABLE public.tab IS NULL") {
2942-
Statement::Comment {
2943-
object_type,
2944-
object_name,
2945-
comment: None,
2946-
if_exists,
2947-
} => {
2948-
assert_eq!("public.tab", object_name.to_string());
2949-
assert_eq!(CommentObject::Table, object_type);
2950-
assert!(if_exists);
2951-
}
2952-
_ => unreachable!(),
2953-
}
2954-
}
2955-
29562894
#[test]
29572895
fn parse_quoted_identifier() {
29582896
pg_and_generic().verified_stmt(r#"SELECT "quoted "" ident""#);

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