Kunal Khatua created DRILL-6727:
-----------------------------------
Summary: JPPD does not eliminate rows using the bloom filter if a
HashJoin is involved
Key: DRILL-6727
URL: https://issues.apache.org/jira/browse/DRILL-6727
Project: Apache Drill
Issue Type: Improvement
Components: Execution - Flow
Affects Versions: 1.15.0
Environment: When testing a simple join between 2 tables, it appears
that the Bloom-filter based predicate pushdown will work only for broadcast
joins, but not for hash-based joins.
Since the purpose of the filter is to reduce the number of records being hashed
across the fragments, the runtime does not improve.
Join Query (TPCH dataset):
{code:sql}
select
l.l_orderkey
, sum(l.l_extendedprice * (1 - l.l_discount)) as revenue
, o.o_orderdate
, o.o_shippriority
from
orders o
, lineitem l
where
l.l_orderkey = o.o_orderkey
and o.o_orderdate = date '1994-08-26'
and MOD(o.o_custkey,10) = 1
group by
l.l_orderkey
, o.o_orderdate
, o.o_shippriority
order by
revenue desc
, o.o_orderdate limit 10;
{code}
This generates an output of about 6K rows from the build side, with the
expectation of 10M rows being joined from the probe side.
Following are the results of the following query:
|| Join Mode || Profile || Runtime || Status ||
|BCastJoin w/o JPPD | 2477fa68-a31e-3b97-5469-373845c2b763 | 3.148sec | As
expected. 600M rows are scanned and probed against the locally available hash
table. |
|BCastJoin w/ JPPD | 2477fb99-36cb-9bc2-b7fb-c81a52b256d2 | 3.570sec | 04-xx-06
shows a reduction in rows. 600M rows are scanned, but only 10M rows are probed
against the locally available hash table. |
|
|HashJoin w/o JPPD | 2477f5e8-fff2-fc83-d251-d8be8f92820b | 5.861sec | As
expected. 600M rows are scanned and probed against the hash table. |
|HashJoin w/ JPPD | 2477f6f7-14e0-ca23-d9f7-6b0273c20964 | 8.376sec | 03-xx-07
is not seeing a reduction in rows. All 600M rows are scanned and probed against
the hash table. |
There are a few possibilities of why the RuntimeFilter does not eliminate any
rows when a HashJoin is involved.
1. The RuntimeFilter operator does not have a bloom-filter
2. The RuntimeFilter receives the bloom-filter after the scan completes,
because the foreman has not finished building and distributing the global
bloom-filter
3. The RuntimeFilter receives the bloom-filter during the scan, but does not
apply it.
Reporter: Kunal Khatua
Assignee: weijie.tong
Attachments: bcastJoin-JPPD_2477fb99-36cb-9bc2-b7fb-c81a52b256d2.json,
bcastJoin-default_2477fa68-a31e-3b97-5469-373845c2b763.json,
hashJoin-JPPD_2477f6f7-14e0-ca23-d9f7-6b0273c20964.json,
hashJoin-default_2477f5e8-fff2-fc83-d251-d8be8f92820b.json
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