Introduce new Keyword FETCH FIRST N ROWS ONLY in Presto Query

Issue details : #18935

We are introducing a new keyword FETCH FIRST N ROWS ONLY which can be used in presto queries. The keyword will work in sql queries just like LIMIT keyword to limit the number of rows returned from an sql select query.

For Example : select * from table FETCH FIRST 3 ROWS ONLY will return only 3 rows as a result of the sql query.

== RELEASE NOTES ==

General Changes

Introducing a new Keyword FETCH FIRST N ROWS ONLY to the Presto Query

presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4

@@ -223,6 +223,7 @@ externalRoutineName
 queryNoWith:
       queryTerm
       (ORDER BY sortItem (',' sortItem)*)?
+      (FETCH FIRST fetchFirstNRows=INTEGER_VALUE ROWS ONLY)?
       (OFFSET offset=INTEGER_VALUE (ROW | ROWS)?)?
       (LIMIT limit=(INTEGER_VALUE | ALL))?
     ;
@@ -566,7 +567,7 @@ nonReserved
     | CALL | CALLED | CASCADE | CATALOGS | COLUMN | COLUMNS | COMMENT | COMMIT | COMMITTED | CURRENT | CURRENT_ROLE
     | DATA | DATE | DAY | DEFINER | DESC | DETERMINISTIC | DISTRIBUTED
     | EXCLUDING | EXPLAIN | EXTERNAL
-    | FILTER | FIRST | FOLLOWING | FORMAT | FUNCTION | FUNCTIONS
+    | FETCH | FILTER | FIRST | FOLLOWING | FORMAT | FUNCTION | FUNCTIONS
     | GRANT | GRANTED | GRANTS | GRAPHVIZ
     | HOUR
     | IF | IGNORE | INCLUDING | INPUT | INTERVAL | INVOKER | IO | ISOLATION
@@ -645,6 +646,7 @@ EXPLAIN: 'EXPLAIN';
 EXTRACT: 'EXTRACT';
 EXTERNAL: 'EXTERNAL';
 FALSE: 'FALSE';
+FETCH: 'FETCH';
 FILTER: 'FILTER';
 FIRST: 'FIRST';
 FOLLOWING: 'FOLLOWING';

presto-parser/src/main/java/com/facebook/presto/sql/parser/AstBuilder.java

@@ -734,6 +734,14 @@ public Node visitQueryNoWith(SqlBaseParser.QueryNoWithContext context)
             offset = Optional.of(new Offset(Optional.of(getLocation(context.OFFSET())), getTextIfPresent(context.offset).orElseThrow(() -> new IllegalStateException("Missing OFFSET row count"))));
         }
 
+        Optional<String> limit = Optional.empty();
+        if (context.LIMIT() != null) {
+            limit = getTextIfPresent(context.limit);
+        }
+        else if (context.FETCH() != null) {
+            limit = getTextIfPresent(context.fetchFirstNRows);
+        }
+
         if (term instanceof QuerySpecification) {
             // When we have a simple query specification
             // followed by order by, offset, limit, fold the order by and limit
@@ -754,7 +762,7 @@ public Node visitQueryNoWith(SqlBaseParser.QueryNoWithContext context)
                             query.getHaving(),
                             orderBy,
                             offset,
-                            getTextIfPresent(context.limit)),
+                            limit),
                     Optional.empty(),
                     Optional.empty(),
                     Optional.empty());
@@ -766,7 +774,7 @@ public Node visitQueryNoWith(SqlBaseParser.QueryNoWithContext context)
                 term,
                 orderBy,
                 offset,
-                getTextIfPresent(context.limit));
+                limit);
     }
 
     @Override

presto-parser/src/test/java/com/facebook/presto/sql/parser/TestSqlParser.java

@@ -961,6 +961,22 @@ public void testSelectWithOffset()
                         Optional.empty(),
                         Optional.empty()));
 
+        assertStatement("SELECT * FROM table1 order by x FETCH FIRST 10 ROWS ONLY",
+                new Query(
+                        Optional.empty(),
+                        new QuerySpecification(
+                                selectList(new AllColumns()),
+                                Optional.of(new Table(QualifiedName.of("table1"))),
+                                Optional.empty(),
+                                Optional.empty(),
+                                Optional.empty(),
+                                Optional.of(new OrderBy(ImmutableList.of(new SortItem(new Identifier("x"), ASCENDING, UNDEFINED)))),
+                                Optional.empty(),
+                                Optional.of("10")),
+                        Optional.empty(),
+                        Optional.empty(),
+                        Optional.empty()));
+
         Query valuesQuery = query(values(
                 row(new LongLiteral("1"), new StringLiteral("1")),
                 row(new LongLiteral("2"), new StringLiteral("2"))));

presto-parser/src/test/java/com/facebook/presto/sql/parser/TestSqlParserErrorHandling.java

@@ -49,7 +49,7 @@ public Object[][] getStatements()
                 {"select * from 'oops",
                  "line 1:15: mismatched input '''. Expecting: '(', 'LATERAL', 'UNNEST', <identifier>"},
                 {"select *\nfrom x\nfrom",
-                 "line 3:1: mismatched input 'from'. Expecting: ',', '.', 'AS', 'CROSS', 'EXCEPT', 'FULL', 'GROUP', 'HAVING', 'INNER', 'INTERSECT', 'JOIN', 'LEFT', 'LIMIT', 'NATURAL', 'OFFSET', " +
+                 "line 3:1: mismatched input 'from'. Expecting: ',', '.', 'AS', 'CROSS', 'EXCEPT', 'FETCH', 'FULL', 'GROUP', 'HAVING', 'INNER', 'INTERSECT', 'JOIN', 'LEFT', 'LIMIT', 'NATURAL', 'OFFSET', " +
                          "'ORDER', 'RIGHT', 'TABLESAMPLE', 'UNION', 'WHERE', <EOF>, <identifier>"},
                 {"select *\nfrom x\nwhere from",
                  "line 3:7: mismatched input 'from'. Expecting: <expression>"},
@@ -112,7 +112,7 @@ public Object[][] getStatements()
                 {"SELECT foo(*) filter (",
                  "line 1:23: mismatched input '<EOF>'. Expecting: 'WHERE'"},
                 {"SELECT * FROM t t x",
-                 "line 1:19: mismatched input 'x'. Expecting: '(', ',', 'CROSS', 'EXCEPT', 'FULL', 'GROUP', 'HAVING', 'INNER', 'INTERSECT', 'JOIN', 'LEFT', 'LIMIT', 'NATURAL', 'OFFSET', 'ORDER', " +
+                 "line 1:19: mismatched input 'x'. Expecting: '(', ',', 'CROSS', 'EXCEPT', 'FETCH', 'FULL', 'GROUP', 'HAVING', 'INNER', 'INTERSECT', 'JOIN', 'LEFT', 'LIMIT', 'NATURAL', 'OFFSET', 'ORDER', " +
                          "'RIGHT', 'TABLESAMPLE', 'UNION', 'WHERE', <EOF>"},
                 {"SELECT * FROM t WHERE EXISTS (",
                  "line 1:31: mismatched input '<EOF>'. Expecting: <query>"},