feat: add cursor statements (#5094)

* feat: add sql parsers for cursor operations

* feat: cursor operator

* feat: implement RecordBatchStreamCursor

* feat: implement cursor storage and execution

* test: add tests

* chore: update docstring

* feat: add a temporary sql rewrite for cast in limit

this issue is described in #5097

* test: add more sql for cursor integration test

* feat: reject non-select query for cursor statement

* refactor: address review issues

* test: add empty result case

* feat: address review comments

src/servers/src/postgres/fixtures.rs

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::borrow::Cow;
 use std::collections::HashMap;
 use std::sync::Arc;
 
@@ -112,6 +113,13 @@ pub(crate) fn process<'a>(query: &str, query_ctx: QueryContextRef) -> Option<Vec
     }
 }
 
+static LIMIT_CAST_PATTERN: Lazy<Regex> =
+    Lazy::new(|| Regex::new("(?i)(LIMIT\\s+\\d+)::bigint").unwrap());
+pub(crate) fn rewrite_sql(query: &str) -> Cow<'_, str> {
+    //TODO(sunng87): remove this when we upgraded datafusion to 43 or newer
+    LIMIT_CAST_PATTERN.replace_all(query, "$1")
+}
+
 #[cfg(test)]
 mod test {
     use session::context::{QueryContext, QueryContextRef};
@@ -195,4 +203,13 @@ mod test {
         assert!(process("SHOW TABLES ", query_context.clone()).is_none());
         assert!(process("SET TIME_ZONE=utc ", query_context.clone()).is_none());
     }
+
+    #[test]
+    fn test_rewrite() {
+        let sql = "SELECT * FROM number LIMIT 1::bigint";
+        let sql2 = "SELECT * FROM number limit      1::BIGINT";
+
+        assert_eq!("SELECT * FROM number LIMIT 1", rewrite_sql(sql));
+        assert_eq!("SELECT * FROM number limit      1", rewrite_sql(sql2));
+    }
 }

src/servers/src/postgres/handler.rs

@@ -70,6 +70,9 @@ impl SimpleQueryHandler for PostgresServerHandlerInner {
             return Ok(vec![Response::EmptyQuery]);
         }
 
+        let query = fixtures::rewrite_sql(query);
+        let query = query.as_ref();
+
         if let Some(resps) = fixtures::process(query, query_ctx.clone()) {
             send_warning_opt(client, query_ctx).await?;
             Ok(resps)
@@ -229,6 +232,9 @@ impl QueryParser for DefaultQueryParser {
             });
         }
 
+        let sql = fixtures::rewrite_sql(sql);
+        let sql = sql.as_ref();
+
         let mut stmts =
             ParserContext::create_with_dialect(sql, &PostgreSqlDialect {}, ParseOptions::default())
                 .map_err(|e| PgWireError::ApiError(Box::new(e)))?;