Github user jinfengni commented on a diff in the pull request: https://github.com/apache/drill/pull/169#discussion_r40484523 --- Diff: exec/java-exec/src/test/java/org/apache/drill/exec/physical/impl/limit/TestLimitWithExchanges.java --- @@ -26,4 +30,34 @@ public void testLimitWithExchanges() throws Exception{ testPhysicalFromFile("limit/limit_exchanges.json"); } + + @Test + public void testPushLimitPastUnionExchange() throws Exception { + // Push limit past through UnionExchange. + final String WORKING_PATH = TestTools.getWorkingPath(); + final String TEST_RES_PATH = WORKING_PATH + "/src/test/resources"; + + try { + // case 1. single table query. + final String sql = String.format("select * from dfs_test.`%s/tpchmulti/region` limit 1 offset 2", TEST_RES_PATH); + test("alter session set `planner.slice_target` = 1"); + // test(sql); + + // Validate the plan + final String[] expectedPlan = {"(?s)Limit.*UnionExchange.*Limit.*Scan"}; + final String[] excludedPatterns = {}; + PlanTestBase.testPlanMatchingPatterns(sql, expectedPlan, excludedPatterns); + + // case 2: join query. + final String sql2 = String.format("select * from dfs_test.`%s/tpchmulti/region` r, dfs_test.`%s/tpchmulti/nation` n where r.r_regionkey = n.n_regionkey limit 1 offset 2", TEST_RES_PATH, TEST_RES_PATH ); + // Validate the plan + final String[] expectedPlan2 = {"(?s)Limit.*UnionExchange.*Limit.*Join"}; + final String[] excludedPatterns2 = {}; + PlanTestBase.testPlanMatchingPatterns(sql2, expectedPlan2, excludedPatterns2); + } finally { + test("alter session set `planner.slice_target` = " + ExecConstants.SLICE_TARGET_OPTION.getDefault().getValue()); + } + // test(sql2); --- End diff -- Removed that.
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