iffyio commented on code in PR #1614:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/1614#discussion_r1907585091
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src/ast/mod.rs:
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@@ -7278,16 +7279,126 @@ impl fmt::Display for SearchModifier {
}
}
+/// A `LOCK TABLE ..` statement. MySQL and Postgres variants are supported.
+///
+/// The MySQL and Postgres syntax variants are significant enough that they
+/// are explicitly represented as enum variants. In order to support additional
+/// databases in the future, this enum is marked as `#[non_exhaustive]`.
+///
+/// In MySQL, when multiple tables are mentioned in the statement the lock mode
+/// can vary per table.
+///
+/// In contrast, Postgres only allows specifying a single mode which is applied
+/// to all mentioned tables.
+///
+/// MySQL: see <https://dev.mysql.com/doc/refman/8.0/en/lock-tables.html>
+///
+/// ```sql
+/// LOCK [TABLE | TABLES] name [[AS] alias] locktype [,name [[AS] alias]
locktype]
+/// ````
+///
+/// Where *locktype* is:
+/// ```sql
+/// READ [LOCAL] | [LOW_PRIORITY] WRITE
+/// ```
+///
+/// Postgres: See <https://www.postgresql.org/docs/current/sql-lock.html>
+///
+/// ```sql
+/// LOCK [ TABLE ] [ ONLY ] name [, ...] [ IN lockmode MODE ] [ NOWAIT ]
+/// ```
+/// Where *lockmode* is one of:
+///
+/// ```sql
+/// ACCESS SHARE | ROW SHARE | ROW EXCLUSIVE | SHARE UPDATE EXCLUSIVE
+/// | SHARE | SHARE ROW EXCLUSIVE | EXCLUSIVE | ACCESS EXCLUSIVE
+/// ``````
#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
-pub struct LockTable {
- pub table: Ident,
+#[non_exhaustive]
+pub enum LockTables {
Review Comment:
Yeah I agree that downstream crates targeting a single dialect would be
easier to implement by essentially having dialect specific AST representations
(on the other extreme there are downstream crates that would like to process
the AST in a dialect agnostic manner,, we also have custom dialects in other
downstream crates that need support). I think there are pros/cons to this
approach vs the current one followed by the parser which puts some of the
responsibility on the downstream crate. I'm thinking in any case ideally we
would want to keep to the current approach for the PR while shift in approaches
could be tackled as its own dedicated proposal.
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