| # 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. |
| |
| # Tests the TABLESAMPLE clause. |
| |
| import pytest |
| |
| from tests.common.impala_test_suite import ImpalaTestSuite |
| from tests.common.test_vector import ImpalaTestDimension |
| |
| class TestTableSample(ImpalaTestSuite): |
| @classmethod |
| def get_workload(cls): |
| return 'functional-query' |
| |
| @classmethod |
| def add_test_dimensions(cls): |
| super(TestTableSample, cls).add_test_dimensions() |
| cls.ImpalaTestMatrix.add_dimension(ImpalaTestDimension('repeatable', *[True, False])) |
| # Tablesample is only supported on HDFS tables. |
| cls.ImpalaTestMatrix.add_constraint(lambda v: |
| v.get_value('table_format').file_format != 'kudu' and |
| v.get_value('table_format').file_format != 'hbase') |
| if cls.exploration_strategy() != 'exhaustive': |
| # Cut down on core testing time by limiting the file formats. |
| cls.ImpalaTestMatrix.add_constraint(lambda v: |
| v.get_value('table_format').file_format == 'parquet' or |
| v.get_value('table_format').file_format == 'text') |
| |
| def test_tablesample(self, vector): |
| # Do not use a .test to avoid making this test flaky. |
| # 1. Queries without the repeatable clause are non-deterministic. |
| # 2. The results of queries without a repeatable clause could change due to |
| # changes in data loading that affect the number or size of files. |
| repeatable = vector.get_value('repeatable') |
| ImpalaTestSuite.change_database(self.client, vector.get_value('table_format')) |
| result = self.client.execute("select count(*) from alltypes") |
| baseline_count = int(result.data[0]) |
| prev_count = None |
| for perc in [5, 20, 50]: |
| rep_sql = "" |
| if repeatable: rep_sql = " repeatable(1)" |
| result = self.client.execute( |
| "select count(*) from alltypes tablesample system(%s)%s" % (perc, rep_sql)) |
| count = int(result.data[0]) |
| assert count < baseline_count |
| if prev_count and repeatable: |
| # May not necessarily be true for non-repeatable samples |
| assert count > prev_count |
| prev_count = count |