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Object size relationship to partition size?

User_L0XYY
User_L0XYY Member Posts: 8 Red Ribbon
edited Oct 18, 2017 12:05AM in Coherence Support

Do the partitions within a cache have a size limit?

For example:

cluster size 25 (all local storage enabled)

high unit limit: 1000MB (per cluster node)

partition count: 257

backup count: 1

For the example above, there will be 10 partitions per node.  Will each partition be internally limited to store 100MB (i.e. 1000MB high unit limit / 10 partitions)?  Or is the 1000MB high unit limit only applied at the node-level?  If it is the former, then my assumption is that I will not be able to store any single object larger than 100MB.  If it is the latter AND the object sizes vary by a lot, my assumption is that although the individual partitions may contain the same number of objects they will vary widely in units consumed.  Either way, I may face some challenges if my objects are huge, but I would like to know what I am up against.

Thanks,

Answers

  • Tmiddlet-Oracle
    Tmiddlet-Oracle Member Posts: 125
    edited Oct 17, 2017 10:22PM

    Hi.

    The high-unit is per cache per partition.

    So if you had 10 caches then they could store 100MB per cache per partition.

    Hope this helps.

  • User_L0XYY
    User_L0XYY Member Posts: 8 Red Ribbon
    edited Oct 17, 2017 11:50PM

    >> The high-unit is per cache per partition.

    I don't think so...  Assume that for my example above, there is a single named cache distributed across 25 instances.  So understanding is that the partition count applies to the whole cache (e.g. 257 partitions spread across the 25 instances, or about 10 partitions per instance).  The high units is per cache per instance (e.g. 1000MB on each of 25 instances)

  • Tmiddlet-Oracle
    Tmiddlet-Oracle Member Posts: 125
    edited Oct 18, 2017 12:05AM

    Yes my mistake, it is high-unit per cache per storage-enabled server (25 instances as you are calling them). Each storage-enabled server manages, n-partitions or approx 10 in your case.

    So if you are setting high-units for a cache then it will apply for all the partitions owned by that storage-enabled member, eg. high-units / owned partitions.

    One thing to note is that for partitioned backing maps (https://docs.oracle.com/middleware/1221/coherence/develop-applications/cache_back.htm#COHDG1379 then the high-units is by partition as each partition has its own backing map.

    Thanks

    Tim

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