[doris] 03/05: [fix](olap) dictionary cannot be sorted after inserting some null values (#15829)

[mo...@apache.org]

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morningman pushed a commit to branch branch-1.2-lts
in repository https://gitbox.apache.org/repos/asf/doris.git

commit 915abc8c53414a6169f8018e4cac45cb38a1a9d1
Author: Jerry Hu <mr...@gmail.com>
AuthorDate: Fri Jan 13 09:28:55 2023 +0800

    [fix](olap) dictionary cannot be sorted after inserting some null values (#15829)
---
 be/src/vec/columns/column_dictionary.h             |  6 +++
 .../suites/query_p0/test_dict_with_null.groovy     | 46 ++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/be/src/vec/columns/column_dictionary.h b/be/src/vec/columns/column_dictionary.h
index 422e2fdfbb..95cd848763 100644
--- a/be/src/vec/columns/column_dictionary.h
+++ b/be/src/vec/columns/column_dictionary.h
@@ -240,6 +240,12 @@ public:
     }
 
     void convert_dict_codes_if_necessary() override {
+        // Avoid setting `_dict_sorted` to true when `_dict` is empty.
+        // Because `_dict` maybe keep empty after inserting some null rows.
+        if (_dict.empty()) {
+            return;
+        }
+
         if (!is_dict_sorted()) {
             _dict.sort();
             _dict_sorted = true;
diff --git a/regression-test/suites/query_p0/test_dict_with_null.groovy b/regression-test/suites/query_p0/test_dict_with_null.groovy
new file mode 100644
index 0000000000..a5c84444ae
--- /dev/null
+++ b/regression-test/suites/query_p0/test_dict_with_null.groovy
@@ -0,0 +1,46 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("dict_with_null", "query") {
+    def tableName = "test_dict_with_null"
+    sql "DROP TABLE IF EXISTS ${tableName}"
+    sql """
+        CREATE TABLE IF NOT EXISTS ${tableName} (
+          c_int INT,
+          c_string VARCHAR(10)
+        )
+        DISTRIBUTED BY HASH(c_int) BUCKETS 1
+        PROPERTIES (
+          "replication_num" = "1"
+        )
+    """
+
+    // Here insert all rows in one statement to make sure they are in one same segment.
+    // Insert 100 + 1 rows because `SegmentIterator` will read 100 rows in the first time.
+    // The first 100 rows are all null to make no record be inserted into dictionary at the first read time.
+    def insert_sql = "insert into ${tableName} values "
+    for (int i in 1..100) {
+        if (i != 1) {
+            insert_sql += ", "
+        }
+        insert_sql += "(${i}, null)"
+    }
+    insert_sql += ", (101, 'abc')"
+
+    sql insert_sql
+    sql "select * from test_dict_with_null where c_string > '0'"
+}
\ No newline at end of file


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