Ulrich Kramer created CALCITE-6236:
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Summary: EnumerableBatchNestedLoopJoin uses wrong row count for
cost calculation
Key: CALCITE-6236
URL: https://issues.apache.org/jira/browse/CALCITE-6236
Project: Calcite
Issue Type: Bug
Reporter: Ulrich Kramer
{{EnumerableBatchNestedLoopJoin}} always adds a {{Filter}} on the right
relation.
This filter reduces the number of rows by it's selectivity (in our case by a
factor of 4).
Therefore, {{RelMdUtil.getJoinRowCount}} returns a value 4 times lower compared
to the one returned for a {{JdbcJoin}}.
This leads to the fact that in most cases {{EnumerableBatchNestedLoopJoin}} is
preferred over {{JdbcJoin}}.
This is an example for the different costs
{code}
EnumerableProject rows=460.0 self_costs=460.0 cumulative_costs=1465.0
EnumerableBatchNestedLoopJoin rows=460.0 self_costs=687.5
cumulative_costs=1005.0
JdbcToEnumerableConverter rows=100.0 self_costs=10.0 cumulative_costs=190.0
JdbcProject rows=100.0 self_costs=80.0 cumulative_costs=180.0
JdbcTableScan rows=100.0 self_costs=100.0 cumulative_costs=100.0
JdbcToEnumerableConverter rows=25.0 self_costs=2.5 cumulative_costs=127.5
JdbcFilter rows=25.0 self_costs=25.0 cumulative_costs=125.0
JdbcTableScan rows=100.0 self_costs=100.0 cumulative_costs=100.0
{code}
vs.
{code}
JdbcToEnumerableConverter rows=1585.0 self_costs=158.5 cumulative_costs=2023.5
JdbcJoin rows=1585.0 self_costs=1585.0 cumulative_costs=1865.0
JdbcProject rows=100.0 self_costs=80.0 cumulative_costs=180.0
JdbcTableScan rows=100.0 self_costs=100.0 cumulative_costs=100.0
JdbcTableScan rows=100.0 self_costs=100.0 cumulative_costs=100.0
{code}
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