From bbe7fd4cecf745325f48b383b6f86e360ea7d42b Mon Sep 17 00:00:00 2001
From: Piotr Findeisen <piotr.findeisen@gmail.com>
Date: Wed, 28 Jul 2021 09:52:52 +0200
Subject: [PATCH] Avoid redundant metastore calls for non-system Iceberg tables

When table name doesn't look like a system table, we can exit early.
---
 .../io/trino/plugin/iceberg/IcebergMetadata.java |  4 ++++
 .../TestIcebergMetastoreAccessOperations.java    | 16 ++++++++--------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java b/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java
index a9cee57b0d3f..759a37ae380a 100644
--- a/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java
+++ b/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java
@@ -303,6 +303,9 @@ public Optional<SystemTable> getSystemTable(ConnectorSession session, SchemaTabl
     private Optional<SystemTable> getRawSystemTable(ConnectorSession session, SchemaTableName tableName)
     {
         IcebergTableName name = IcebergTableName.from(tableName.getTableName());
+        if (name.getTableType() == DATA) {
+            return Optional.empty();
+        }
 
         Optional<Table> hiveTable = metastore.getTable(new HiveIdentity(session), tableName.getSchemaName(), name.getTableName());
         if (hiveTable.isEmpty() || !isIcebergTable(hiveTable.get())) {
@@ -314,6 +317,7 @@ private Optional<SystemTable> getRawSystemTable(ConnectorSession session, Schema
         SchemaTableName systemTableName = new SchemaTableName(tableName.getSchemaName(), name.getTableNameWithType());
         switch (name.getTableType()) {
             case DATA:
+                // Handled above.
                 break;
             case HISTORY:
                 if (name.getSnapshotId().isPresent()) {
diff --git a/plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergMetastoreAccessOperations.java b/plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergMetastoreAccessOperations.java
index f2cfb9be3e5d..5d4741ef022f 100644
--- a/plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergMetastoreAccessOperations.java
+++ b/plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergMetastoreAccessOperations.java
@@ -83,7 +83,7 @@ public void testCreateTable()
                 ImmutableMultiset.builder()
                         .add(CREATE_TABLE)
                         .add(GET_DATABASE)
-                        .addCopies(GET_TABLE, 2)
+                        .add(GET_TABLE)
                         .build());
     }
 
@@ -94,7 +94,7 @@ public void testCreateTableAsSelect()
                 ImmutableMultiset.builder()
                         .add(GET_DATABASE)
                         .add(CREATE_TABLE)
-                        .addCopies(GET_TABLE, 2)
+                        .add(GET_TABLE)
                         .build());
     }
 
@@ -105,7 +105,7 @@ public void testSelect()
 
         assertMetastoreInvocations("SELECT * FROM test_select_from",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 12)
+                        .addCopies(GET_TABLE, 8)
                         .build());
     }
 
@@ -116,7 +116,7 @@ public void testSelectWithFilter()
 
         assertMetastoreInvocations("SELECT * FROM test_select_from_where WHERE age = 2",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 12)
+                        .addCopies(GET_TABLE, 8)
                         .build());
     }
 
@@ -128,7 +128,7 @@ public void testJoin()
 
         assertMetastoreInvocations("SELECT name, age FROM test_join_t1 JOIN test_join_t2 ON test_join_t2.id = test_join_t1.id",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 24)
+                        .addCopies(GET_TABLE, 16)
                         .build());
     }
 
@@ -139,7 +139,7 @@ public void testExplainSelect()
 
         assertMetastoreInvocations("EXPLAIN SELECT * FROM test_explain",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 11)
+                        .addCopies(GET_TABLE, 7)
                         .build());
     }
 
@@ -150,7 +150,7 @@ public void testShowStatsForTable()
 
         assertMetastoreInvocations("SHOW STATS FOR test_show_stats",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 9)
+                        .addCopies(GET_TABLE, 5)
                         .build());
     }
 
@@ -161,7 +161,7 @@ public void testShowStatsForTableWithFilter()
 
         assertMetastoreInvocations("SHOW STATS FOR (SELECT * FROM test_show_stats_with_filter where age >= 2)",
                 ImmutableMultiset.builder()
-                        .addCopies(GET_TABLE, 9)
+                        .addCopies(GET_TABLE, 5)
                         .build());
     }