From 247b65d63e9864b7dee707dc5151e3972405472c Mon Sep 17 00:00:00 2001
From: Yuya Ebihara <ebyhry@gmail.com>
Date: Thu, 13 Feb 2025 08:51:01 +0900
Subject: [PATCH] Fix duplicate key due to non-lowercase collections in MongoDB

---
 .../io/trino/plugin/mongodb/MongoSession.java |  4 ++-
 .../mongodb/TestMongoConnectorTest.java       | 35 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/plugin/trino-mongodb/src/main/java/io/trino/plugin/mongodb/MongoSession.java b/plugin/trino-mongodb/src/main/java/io/trino/plugin/mongodb/MongoSession.java
index cbd592597d9d..a98045b15f0f 100644
--- a/plugin/trino-mongodb/src/main/java/io/trino/plugin/mongodb/MongoSession.java
+++ b/plugin/trino-mongodb/src/main/java/io/trino/plugin/mongodb/MongoSession.java
@@ -247,7 +247,9 @@ public Set<String> getAllTables(String schema)
                 .collect(toSet()));
         builder.addAll(getTableMetadataNames(schemaName));
 
-        return builder.build();
+        return builder.build().stream()
+                .map(name -> name.toLowerCase(ENGLISH))
+                .collect(toImmutableSet());
     }
 
     public MongoTable getTable(SchemaTableName tableName)
diff --git a/plugin/trino-mongodb/src/test/java/io/trino/plugin/mongodb/TestMongoConnectorTest.java b/plugin/trino-mongodb/src/test/java/io/trino/plugin/mongodb/TestMongoConnectorTest.java
index 8131a8c28445..324cffb39163 100644
--- a/plugin/trino-mongodb/src/test/java/io/trino/plugin/mongodb/TestMongoConnectorTest.java
+++ b/plugin/trino-mongodb/src/test/java/io/trino/plugin/mongodb/TestMongoConnectorTest.java
@@ -57,6 +57,7 @@
 import static io.trino.testing.TestingNames.randomNameSuffix;
 import static java.lang.String.format;
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Locale.ENGLISH;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.junit.jupiter.api.Assumptions.abort;
@@ -149,6 +150,40 @@ public void testSortItemsReflectedInExplain()
                 "TopNPartial\\[count = 5, orderBy = \\[nationkey DESC");
     }
 
+    @Test
+    void testNonLowercaseCollection()
+    {
+        String suffix = randomNameSuffix();
+        String schema = "test_db_" + suffix;
+        String table = "test_collection_" + suffix;
+        String mixedTable = "Test_Collection_" + suffix;
+        try {
+            MongoDatabase db = client.getDatabase(schema);
+
+            db.createCollection(table);
+            db.getCollection(table).insertOne(new Document("lowercase", 1));
+
+            db.createCollection(mixedTable);
+            db.getCollection(mixedTable).insertOne(new Document("mixed", 2));
+
+            assertThatThrownBy(() -> client.getDatabase(schema.toUpperCase(ENGLISH)).createCollection(table))
+                    .hasMessageContaining("db already exists with different case");
+
+            db.createCollection(table.toUpperCase(ENGLISH));
+            db.getCollection(table.toUpperCase(ENGLISH)).insertOne(new Document("uppercase", 3));
+
+            assertThat(query("SELECT * FROM information_schema.tables WHERE table_catalog = 'mongodb' AND table_schema = '" + schema + "'"))
+                    .matches("VALUES (VARCHAR 'mongodb', VARCHAR '" + schema + "', VARCHAR '" + table + "', VARCHAR 'BASE TABLE')");
+            assertThat(query("SELECT table_name, column_name FROM information_schema.columns WHERE table_catalog = 'mongodb' AND table_schema = '" + schema + "'"))
+                    .matches("VALUES (VARCHAR '" + table + "', VARCHAR 'lowercase')");
+            assertThat(query("SELECT * FROM " + schema + "." + table))
+                    .matches("VALUES BIGINT '1'");
+        }
+        finally {
+            client.getDatabase(schema).drop();
+        }
+    }
+
     @Override
     protected Optional<DataMappingTestSetup> filterDataMappingSmokeTestData(DataMappingTestSetup dataMappingTestSetup)
     {