[MySQL, Oracle] Parse optimizer hints for MERGEs

Author: xitep

src/ast/dml.rs

@@ -348,6 +348,10 @@ impl Display for Update {
 pub struct Merge {
     /// The `MERGE` token that starts the statement.
     pub merge_token: AttachedToken,
+    /// A query optimizer hint
+    ///
+    /// [Oracle](https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Comments.html#GUID-D316D545-89E2-4D54-977F-FC97815CD62E)
+    pub optimizer_hint: Option<OptimizerHint>,
     /// optional INTO keyword
     pub into: bool,
     /// Specifies the table to merge
@@ -364,13 +368,16 @@ pub struct Merge {
 
 impl Display for Merge {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "MERGE{int} {table} USING {source} ",
-            int = if self.into { " INTO" } else { "" },
+        f.write_str("MERGE")?;
+        if let Some(hint) = self.optimizer_hint.as_ref() {
+            write!(f, " {hint}")?;
+        }
+        if self.into {
+            write!(f, " INTO")?;
+        }
+        write!(f, " {table} USING {source} ",
             table = self.table,
-            source = self.source,
-        )?;
+            source = self.source)?;
         write!(f, "ON {on} ", on = self.on)?;
         write!(f, "{}", display_separated(&self.clauses, " "))?;
         if let Some(ref output) = self.output {

src/ast/spans.rs

@@ -2819,6 +2819,7 @@ WHERE id = 1
         // ~ individual tokens within the statement
         let Statement::Merge(Merge {
             merge_token,
+            optimizer_hint: _,
             into: _,
             table: _,
             source: _,

src/parser/merge.rs

@@ -43,6 +43,7 @@ impl Parser<'_> {
 
     /// Parse a `MERGE` statement
     pub fn parse_merge(&mut self, merge_token: TokenWithSpan) -> Result<Merge, ParserError> {
+        let optimizer_hint = self.parse_optional_optimizer_hint()?;
         let into = self.parse_keyword(Keyword::INTO);
 
         let table = self.parse_table_factor()?;
@@ -59,6 +60,7 @@ impl Parser<'_> {
 
         Ok(Merge {
             merge_token: merge_token.into(),
+            optimizer_hint,
             into,
             table,
             source,

tests/sqlparser_oracle.rs

@@ -380,4 +380,13 @@ fn test_optimizer_hints() {
     // ~ deletes
     oracle_dialect.verified_stmt(
         "DELETE --+ ENABLE_PARALLEL_DML\n FROM table_name");
+
+    // ~ merges
+    oracle_dialect.verified_stmt(
+        "MERGE /*+ CLUSTERING */ INTO people_target pt \
+         USING people_source ps \
+            ON (pt.person_id = ps.person_id) \
+          WHEN NOT MATCHED THEN INSERT \
+               (pt.person_id, pt.first_name, pt.last_name, pt.title) \
+               VALUES (ps.person_id, ps.first_name, ps.last_name, ps.title)");
 }