[DRILL-1309] Projected columns are not pushed into scan

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.5.0
• Assignee: DrillCommitter
• Reporter: Mehant Baid
• Created: 17/Aug/14 01:12
• Updated: 29/Aug/14 17:55
• Resolved: 29/Aug/14 17:55

Description

While performing the following query on two text files, the projected column does not get pushed into the scan.

explain plan for select t1.columns[1] from dfs.`/tmp/t1.csv` t1, dfs.`/tmp/t2.csv` t2 where t1.columns[0] = t2.columns[0];

00-00 Screen
00-01 Project(EXPR$0=[ITEM($0, 1)])
00-02 HashJoin(condition=[=($1, $2)], joinType=[inner])
00-04 Project(columns=[$0], $f2=[ITEM($0, 0)])
00-06 Scan(groupscan=[EasyGroupScan [selectionRoot=/tmp/t1.csv, columns = [SchemaPath [`columns`], SchemaPath [`columns`[0]]]]])
00-03 Project($f20=[$0])
00-05 Project($f2=[ITEM($0, 0)])
00-07 Scan(groupscan=[EasyGroupScan [selectionRoot=/tmp/t2.csv, columns = [SchemaPath [`columns`[0]]]]])

In the above plan (00-06) we see that the scan contains the following column projections pushed into scan: 'columns' and 'columns[0]'.

We should not push 'columns' into the scan, instead push 'columns[1]' which is the projected column into the scan.