vlsi commented on a change in pull request #2363:
URL: https://github.com/apache/calcite/pull/2363#discussion_r591334749
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File path: core/src/test/java/org/apache/calcite/test/RelMetadataTest.java
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@@ -3412,4 +3415,41 @@ public String colType(RelNode rel, int column) {
assertThat(columnOrigin.getOriginTable().getRowType().getFieldNames().get(5),
equalTo("SAL"));
}
+
+ @Test void testSortCpuCostOffsetLimit() {
+ final String sql = "select ename from emp order by ename limit 5 offset 5";
+ double cpuCost = EMP_SIZE * Math.log(10) * 4;
+ checkCpuCost(sql, cpuCost);
+ }
+
+ @Test void testSortCpuCostLimit() {
+ final String sql = "select ename from emp limit 10";
+ checkCpuCost(sql, 0d);
+ }
+
+ @Test void testSortCpuCostLimit0() {
+ final String sql = "select ename from emp order by ename limit 0";
+ checkCpuCost(sql, 0d);
+ }
+
+ @Test void testSortCpuCostLargeLimit() {
+ final String sql = "select ename from emp order by ename limit 10000";
+ double cpuCost = EMP_SIZE * Math.log(EMP_SIZE) * 4;
+ checkCpuCost(sql, cpuCost);
+ }
+
+ private void checkCpuCost(String sql, double expected) {
+ RelNode rel = convertSql(sql);
+ RelOptCost cost = computeRelSelfCost(rel);
+ final double result = cost.getCpu();
+ assertEquals(expected, result, () -> "cpu cost is not as expected <"
+ + expected + ">, but <" + result + ">, plan as follow:\n"
+ + RelOptUtil.toString(rel, SqlExplainLevel.ALL_ATTRIBUTES));
Review comment:
You've added `...<" + expected + ">, but <" + result + ">...` to
the exception message. However, it would make the message complicated with no
extra gain.
`assertEquals` would print `expected` vs `actual` on its own, so `message`
parameter (which you write in the test code) *must not* include `expected vs
actual`.
On the other hand, `message` parameter must explain **why** the value is
expected like that.
For instance: "sort limit exceeds table size => cost should be dominated by
table size", "limit is 0, cost must be 0", and so on.
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