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2 replies Latest Post - ‏2012-12-18T09:43:03Z by mortenb
5 Posts

Pinned topic DB2 ExpressC for smaller projects

‏2012-12-17T14:57:49Z |
I'm testing to see if I can use the DB2 ExpressC for a project instead of MySQL.

Below is the linux top output when running at full speed.

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 2360 db2inst1  20   0 3463m 1.3g 1.1g S  7.4 35.3   4:45.93 db2sysc

I'm perfectly happy with the performance. I'm concerning what will happen when data grows?
I do not need much data, but now it is 1mill, I need to store max 30mill rows.
It will take me 14days to reach with the current simulation.

Will memory usage grow with growing tables, or is it just the indexes?
or is this autotuned DB2 internally? I have max 10connections active and I only see a
small fraction increase in cpu load, I've never been above 30%.

When memory usage(RES) reaches 2GB, will connection fails, or just slow down
using the disks more?, will insert fail, or may I get corrupt data?

Morten Bjoernsvik, Developer Evry CardServices AS, Oslo, Norway
Updated on 2012-12-18T09:43:03Z at 2012-12-18T09:43:03Z by mortenb
  • SystemAdmin
    5837 Posts

    Re: DB2 ExpressC for smaller projects

    ‏2012-12-17T20:14:23Z  in response to mortenb
    You may want to use ExpressC version 10 as memory limits for all DB2 instances on the server is 4GB in free version 10. For Express FTL it is 8GB. If you can get the funding for FTL, get the FTL as you can then get current fixpacks and IBM support.

    Probability of Connection failures depends on point in time memory and IO requirements for the concurrent workload thrown at the server at a point in time. This is where you may need to do either manual tuning or have Db2 do the automatic tuning to prevent thrashing and containing workload.

    Probably you are going to see slow down in performance as db and indexes grow as only so many pages of tables and indexes (depending on number of indexes) can fit in allowed memory.

    You are not going to get data corruption at the DB tablespace/page level. Sure if DB2 worker/agent processes cannot allocate memory to process sql and do insert, it will return an error codes which your application should be managing.
    • mortenb
      5 Posts

      Re: DB2 ExpressC for smaller projects

      ‏2012-12-18T09:43:03Z  in response to SystemAdmin
      Thanks dattark

      Excellent feedback.

      I have a simulation going which will probably give me info about the limits and how they are handled.
      Nice to know that ExpressC can be used as an entry stepping stone.