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Scalability issue with MySQL Cluster

3292561Oct 11 2016 — edited Oct 14 2016

We are evaluating cluster solutions for high volumes(Several Terabytes of Data) and throughput (several hundreds of thousand SQL requests per second . I would like to assess the scalability factor I can expect from MySQL Cluster.

Starting with a simple table (ID bigint(20) PK, DSC varchar(255)), I ran some "performance" tests. By INSERTing 100k records and SELECTing 100k records. Selects made on PK.

Sharding on Data Nodes done by default (Hash of the PK)

Replication factor set to two.

Hardware (for each node) based on 2 CPU and 16 Gb of RAM.

Request are made from a mutli-threaded java client. 32 java threads having each their connection. Using a jdbc:loadbalance://ip1,ip2 ... URL.

First comparison :

(1) 1 SQL Node + 2 Data Nodes

(2) 1 SQL Node + 4 Data Nodes

Time for inserting and select are quite the same. No differences.

13 seconds for INSERTs. 60 seconds for SELECTs

Second comparison :

(1) 1 SQL Node + 2 Data Nodes

(2) 2 SQL Node + 2 Data Nodes

Tests are running 25 % faster for inserts - No change for SELECTs.

9 seconds for INSERTs. 60 seconds for SELECTs

Can anyone what I am doing wrong and how to achieve better scalability?

Thanks in advance

Comments

What version of cluster are you using? 

The slow speed for the selects is suspect.  Are you running the queries from a single process?

3292561

Thanks for your quick answer.

Currently using version MySQL  5.6.31-ndb-7.4.12-cluster-gpl-log on Linux

The 100k selects are made one by one, from a java client using 32 threads in parallel, having each their own connection - Confirmed by show processlist.

Notice I am also worried about the first comparison (No difference when going from 2 Data Nodes to 4 Data Nodes).

You might want to ask on the Java and/or Cluster  groups on http://forums.mysql.com -- there are too many reasons why i think this could be happening but my MySQL Cluster skills are a bit dated.

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Added on Oct 11 2016
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