Github user gparai commented on a diff in the pull request:
https://github.com/apache/drill/pull/817#discussion_r112072391
--- Diff:
contrib/format-maprdb/src/main/java/org/apache/drill/exec/store/mapr/db/MapRDBPushFilterIntoScan.java
---
@@ -137,11 +137,13 @@ protected void
doPushFilterIntoJsonGroupScan(RelOptRuleCall call,
return; //no filter pushdown ==> No transformation.
}
+ // Pass tableStats from old groupScan so we do not go and fetch stats
(an expensive operation) again from MapR DB client.
final JsonTableGroupScan newGroupsScan = new
JsonTableGroupScan(groupScan.getUserName(),
groupScan.getStoragePlugin(),
groupScan.getFormatPlugin(),
newScanSpec,
-
groupScan.getColumns());
+
groupScan.getColumns(),
+
groupScan.getTableStats());
--- End diff --
We should try to use `clone()` here. All we are doing is copying stuff from
one groupscan to another. `JsonTableGroupScan` already has a clone which clones
everything except columns.
`@Override
public GroupScan clone(List<SchemaPath> columns)
{ JsonTableGroupScan newScan = new JsonTableGroupScan(this);
newScan.columns = columns; return newScan; }`
We can create another which would clone everything except scanSpec. This
can be used to pass in the `newScanSpec` generated here. Doing this would also
clone the `regionsToScan` saving the call to `init()`.
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