From 5e5f48559ec060ed6b018515f33977dee0ada397 Mon Sep 17 00:00:00 2001
From: Peng Huo <penghuo@gmail.com>
Date: Thu, 9 Apr 2020 09:58:56 -0700
Subject: [PATCH] Bug fix, support subquery in from doesn't have alias (#418)

---
 .../sql/parser/SubQueryParser.java            |  5 ++--
 .../sql/esintgtest/SubqueryIT.java            | 26 +++++++++++++++++++
 .../unittest/parser/SubQueryParserTest.java   | 15 +++++++++++
 3 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/amazon/opendistroforelasticsearch/sql/parser/SubQueryParser.java b/src/main/java/com/amazon/opendistroforelasticsearch/sql/parser/SubQueryParser.java
index ddf1ad4ead..7b0e19c947 100644
--- a/src/main/java/com/amazon/opendistroforelasticsearch/sql/parser/SubQueryParser.java
+++ b/src/main/java/com/amazon/opendistroforelasticsearch/sql/parser/SubQueryParser.java
@@ -71,8 +71,9 @@ private Select pushSelect(List<SQLSelectItem> selectItems, Select subquerySelect
              * for example, subquerySelectItem is "SUM(emp.empno) as TEMP",
              * and final select list is TEMP. then return true.
              */
-            if (fieldAliasRewriter.containsKey(field.getAlias())) {
-                field.setAlias(fieldAliasRewriter.get(field.getAlias()).apply(field.getAlias()));
+            String fieldIdentifier = Strings.isNullOrEmpty(field.getAlias()) ? field.getName() : field.getAlias();
+            if (fieldAliasRewriter.containsKey(fieldIdentifier)) {
+                field.setAlias(fieldAliasRewriter.get(fieldIdentifier).apply(fieldIdentifier));
             } else {
                 fieldIterator.remove();
             }
diff --git a/src/test/java/com/amazon/opendistroforelasticsearch/sql/esintgtest/SubqueryIT.java b/src/test/java/com/amazon/opendistroforelasticsearch/sql/esintgtest/SubqueryIT.java
index 0c10d7ee84..b006b7a229 100644
--- a/src/test/java/com/amazon/opendistroforelasticsearch/sql/esintgtest/SubqueryIT.java
+++ b/src/test/java/com/amazon/opendistroforelasticsearch/sql/esintgtest/SubqueryIT.java
@@ -36,6 +36,10 @@
 import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.hitAll;
 import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.kvInt;
 import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.kvString;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.rows;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.schema;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.verifyDataRows;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.verifySchema;
 import static org.hamcrest.Matchers.both;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.core.Is.is;
@@ -353,4 +357,26 @@ public void selectFromSubqueryCountAndSum() throws IOException {
         assertThat(result.query("/aggregations/count/value"), equalTo(1000));
         assertThat(result.query("/aggregations/balance/value"), equalTo(25714837.0));
     }
+
+    @Test
+    public void selectFromSubqueryWithoutAliasShouldPass() throws IOException {
+        JSONObject response = executeJdbcRequest(
+                StringUtils.format(
+                        "SELECT a.firstname AS my_first, a.lastname AS my_last, a.age AS my_age " +
+                        "FROM (SELECT firstname, lastname, age " +
+                                "FROM %s " +
+                                "WHERE age = 40 and account_number = 291) AS a",
+                        TEST_INDEX_ACCOUNT));
+
+        verifySchema(response,
+                schema("firstname", "my_first", "text"),
+                schema("lastname", "my_last", "text"),
+                schema("age", "my_age", "long"));
+        verifyDataRows(response,
+                rows("Lynn", "Pollard", 40));
+    }
+
+    private JSONObject executeJdbcRequest(String query) {
+        return new JSONObject(executeQuery(query, "jdbc"));
+    }
 }
diff --git a/src/test/java/com/amazon/opendistroforelasticsearch/sql/unittest/parser/SubQueryParserTest.java b/src/test/java/com/amazon/opendistroforelasticsearch/sql/unittest/parser/SubQueryParserTest.java
index fd05397ecd..cd0c1168c8 100644
--- a/src/test/java/com/amazon/opendistroforelasticsearch/sql/unittest/parser/SubQueryParserTest.java
+++ b/src/test/java/com/amazon/opendistroforelasticsearch/sql/unittest/parser/SubQueryParserTest.java
@@ -46,6 +46,21 @@ public void selectFromSubqueryShouldPass() throws SqlParseException {
         assertEquals("balance1", select.getFields().get(1).getAlias());
     }
 
+    @Test
+    public void selectFromSubqueryWithoutAliasShouldPass() throws SqlParseException {
+        Select select = parseSelect(
+                StringUtils.format(
+                        "SELECT t.age as finalAge, t.balance as finalBalance " +
+                                "FROM (SELECT age, balance FROM %s/account) t",
+                        TEST_INDEX_ACCOUNT));
+
+        assertEquals(2, select.getFields().size());
+        assertEquals("age", select.getFields().get(0).getName());
+        assertEquals("finalAge", select.getFields().get(0).getAlias());
+        assertEquals("balance", select.getFields().get(1).getName());
+        assertEquals("finalBalance", select.getFields().get(1).getAlias());
+    }
+
     @Test
     public void selectFromSubqueryShouldIgnoreUnusedField() throws SqlParseException {
         Select select = parseSelect(