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Tech Tip: eHealth tablespaces and datafiles

  • 1.  Tech Tip: eHealth tablespaces and datafiles

    Posted Sep 05, 2014 09:45 AM

    Oracle has a concept of database storage called tablespaces. Space for tables. Tablespaces however are virtual.

    They are made up physically of datafiles. We see this quite often when a datafile runs out of space and we have

    to add a datafile to a tablepace. Tablespaces can have more than one datafile. Actually, 1022. We create them with

    nhCreateDb. Here is an example:

     

    create tablespace NH_DATA01

    datafile '/export/tspace/oradata/EHEALTH/NH_DATA01a.dbf'

    size 252M

    autoextend on next 25M

    extent management local uniform size 1000K segment space management auto

     

    How does a datafile get full? The maximum datafile size for the type of tablespaces that eHealth uses is calculated by:

     

    Maximum datafile size = db_block_size * maximum number of blocks

     

    eHealth is always set to an 8k db_block_size and the maximum number of blocks in our Oracle versions is 4194303 (set by Oracle).

     

    So:  8K * 4194303 = 32GB

     

    Note: If you are creating LCF files for install or using nhManageDbSpace to add new datafiles, don't use 32GB as a size, use 31, as 32GB is actually one block or 8K over the limit.



  • 2.  Re: Tech Tip: eHealth tablespaces and datafiles

    Posted Aug 27, 2015 05:23 AM

    Good tip. Helpful.