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Date: Wed, 23 Aug 2017 04:40:58 +0000
From: "Tianyi Wang (Code Review)" <gerrit@cloudera.org>
To: Marcel Kornacker <marcelk@gmail.com>, impala-cr@cloudera.com,
        reviews@impala.incubator.apache.org
Message-ID: <gerrit.1503463258000.I7f6efddaea18507482940f5bdab7326b6482b067@gerrit.cloudera.org>
Reply-To: twang@cloudera.com
Subject: =?UTF-8?Q?=5BImpala-ASF-CR=5D_IMPALA-5210=3A_Count_rows_and_collection_items_in_parquet_scanner_separately=0A?=
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archived-at: Wed, 23 Aug 2017 04:41:04 -0000

Tianyi Wang has uploaded a new change for review.

  http://gerrit.cloudera.org:8080/7776

Change subject: IMPALA-5210: Count rows and collection items in parquet scanner separately
......................................................................

IMPALA-5210: Count rows and collection items in parquet scanner separately

This patch addes collection_items_read_counter in scan node, makes
rows_read_counter count top-level rows only, and updates these counters
in a less frequent manner.
When scanning nested columns, current code counts both top-level rows
and nested rows in rows_read_counter, which is inconsistent with
rows_returned_counter. Furthermore, rows_read_counter is updated eagerly
whenever a batch of collection items are read. As a result it spends
around 10% time updating the counter with the following simple query:
> select count(*) from
> customer c,
> c.c_orders o,
> o.o_lineitems l
>where
> c_mktsegment = 'BUILDING'
> and o_orderdate < '1995-03-15'
> and l_shipdate > '1995-03-15' and o_orderkey = 10;

This patch moves collection items couting into
collection_items_read_counter. Both counters are updated every row batch
read. In the query described above, scanning time is decreased by 10.4%.

Change-Id: I7f6efddaea18507482940f5bdab7326b6482b067
---
M be/src/exec/hdfs-parquet-scanner.cc
M be/src/exec/hdfs-parquet-scanner.h
M be/src/exec/parquet-column-readers.cc
M be/src/exec/parquet-column-readers.h
M be/src/exec/scan-node.cc
M be/src/exec/scan-node.h
6 files changed, 77 insertions(+), 48 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/76/7776/1
-- 
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I7f6efddaea18507482940f5bdab7326b6482b067
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tianyi Wang <twang@cloudera.com>