Tuesday, May 10, 2011

Star schema benchmark on MySQL Cluster 7.2

I decided to try the star schema benchmark on our latest 7.2 release (link). Star schema benchmark is an analytics oriented benchmark, and MySQL Cluster has not been developed to address this kind of workload. Nevertheless I couldn't resist trying...

Setup

  • 2 data-nodes each running on a 4-way Xeon E7420 @ 2.13GHx (total 16 cores) 256Gb RAM
  • The mysqld was co-located with one of the data-nodes
  • I used memory tables

Results


Queries: link
Querysf10sf100
Q1.1562
Q1.20.44.6
Q1.30.11.1
Q2.1995
Q2.248495
Q2.351517
Q3.147481
Q3.247476
Q3.3220
Q3.4219
Q4.157572
Q4.257574
Q4.312120

(time in sec, less time is better)

Facts

  • I have done no analysis to why some queries are faster than others
  • This type of queries is currently not in focus of our efforts to improve join performance (nor has it been so far)
  • for lineorder table I specified max_rows=500000000
  • ndb_join_pushdown=on (default in 7.2)

Thoughts and guesses

  • sf100 is almost exactly 10x slower than sf10. So I think a reasonable guess is that sf1000 is 10x slower than sf100
  • Star schema benchmark is an easy benchmark (compared to e.g TPC-H)
  • I think results looks quite good
  • My guess is that scaling out (e.g to 4 nodes) would scale well (although I didn't try) (e.g scale out by running 2 ndbmtd on each machine)
  • Running high write load in parallel doesnt increase query times signficantly (as tested in presentation page 45-46) which is quite cool (although I didn't try this time)

Load procedure for sf100

  • I manually split the 61Gb file (lineorder) into 10 6Gb files (using split(1))
  • Then I loaded these 10 in parallel with 10 clients using load data infile
  • I disabled indexes while loading using ndb_restore --disable-indexes (from an backup made on empty db containing just schema definition)
  • I then rebuilt the indexes using ndb_restore --rebuild-indexes using BuildIndexThreads=15 in config.ini
(for sf10 i did nothing special)

Load time for sf100

  • 4h including rebuilding of indexes

References


Last minute update

  • OleJohn reports that Q2.2 and Q2.3 should be 10x faster if forcing a different join order (e.g by using straight_join or force index). But this I haven't tried

3 comments:

Matty said...

While not designed for data warehousing type workloads, these results demonstrate the possibility of using Cluster into real time analytics workloads on sub 2TB data sets.

Recommendation engines, funnel analysis, etc are all examples of web workloads that could fit

Great job !

Roland Bouman said...

Hi Jonas!

thanks for sharing this!

How many replicas are you using?

Jonas Oreland said...

2 replicas