Ioana Delaney created SPARK-17626:
-------------------------------------
Summary: TPC-DS performance improvements using star-schema
heuristics
Key: SPARK-17626
URL: https://issues.apache.org/jira/browse/SPARK-17626
Project: Spark
Issue Type: Umbrella
Components: SQL
Affects Versions: 2.1.0
Reporter: Ioana Delaney
Priority: Critical
*TPC-DS performance improvements using star-schema heuristics*
\\
\\
TPC-DS consists of multiple snowflake schema, which are multiple star schema
with dimensions linking to dimensions. A star schema consists of a fact table
referencing a number of dimension tables. Fact table holds the main data about
a business. Dimension table, a usually smaller table, describes data reflecting
the dimension/attribute of a business.
\\
\\
As part of the benchmark performance investigation, we observed a pattern of
sub-optimal execution plans of large fact tables joins. Manual rewrite of some
of the queries into selective fact-dimensions joins resulted in significant
performance improvement. This prompted us to develop a simple join reordering
algorithm based on star schema detection. The performance testing using *1TB
TPC-DS workload* shows an overall improvement of *19%*.
\\
\\
*Summary of the results:*
{code}
Passed 99
Failed 0
Total q time (s) 14,962
Max time 1,467
Min time 3
Mean time 145
Geomean 44
{code}
*Compared to baseline* (Negative = improvement; Positive = Degradation):
{code}
End to end improved (%) -19%
Mean time improved (%) -19%
Geomean improved (%) -24%
End to end improved (seconds) -3,603
Number of queries improved (>10%) 45
Number of queries degraded (>10%) 6
Number of queries unchanged 48
Top 10 queries improved (%) -20%
{code}
Cluster: 20-node cluster with each node having:
* 10 2TB hard disks in a JBOD configuration, 2 Intel(R) Xeon(R) CPU E5-2680 v2
@ 2.80GHz processors, 128 GB RAM, 10Gigabit Ethernet.
* Total memory for the cluster: 2.5TB
* Total storage: 400TB
* Total CPU cores: 480
Hadoop stack: IBM Open Platform with Apache Hadoop v4.2. Apache Spark 2.0 GA
Database info:
* Schema: TPCDS
* Scale factor: 1TB total space
* Storage format: Parquet with Snappy compression
Our investigation and results are included in the attached document.
There are two parts to this improvement:
# Join reordering using star schema detection
# New selectivity hint to specify the selectivity of the predicates over base
tables.
\\
\\
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
