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  1. #1
    Join Date
    Apr 2004
    Posts
    190

    Unanswered: Tablespace Question

    Is the block and page buffer completely seperate, or can a block scan use page buffer if the record is already there? (i.e. will the block pool need to be the table size)

  2. #2
    Join Date
    Jan 2007
    Location
    Jena, Germany
    Posts
    2,721
    I don't really understand your question...

    DB2 has its own buffer pool(s) to cache pages that are accessed and potentially modified by DB2. Additionally, the underlying operating system may have a file system cache. Both are not related. For some platforms, you can tell DB2 to use direct I/O and, thus, bypass the file system cache.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  3. #3
    Join Date
    Jan 2008
    Posts
    88
    Or Are you asking about block based bufferpools...Block based bufferpoools are the small part of the bufferpool (depends on u how much % of that u can give to block ) used to read in blocks and it has the same page size of the tablespace

  4. #4
    Join Date
    Apr 2004
    Posts
    190
    Yes I'm talking about a table space that I have designated NUMBLOCKPAGES 75000. This is 50% of the total tablespace size. Are the 2 areas treated as separate entities ?

  5. #5
    Join Date
    Jan 2008
    Posts
    88
    you cannot have NUMBLOCKPAGES for a tablespace. You can assign a part of bufferpool to be NUMBLOCKPAGES which can make that many pages of bufferpool as Block based . And the tablespaces associated with that bufferpool can have access the NUMBLOCKPAGES. But until your database is executing queries with large result set I dont see any reason to have BLOCK based bufferpool

  6. #6
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    Quote Originally Posted by redwolf
    Yes I'm talking about a table space that I have designated NUMBLOCKPAGES 75000. This is 50% of the total tablespace size. Are the 2 areas treated as separate entities ?
    Block area of a block-based bufferpool is only used for sequential prefetch operations. Page area is used for other types of IO operations. In that sense you can say they are treated as separate entities. If too many pages that are to be read by a sequential prefetch are already in the page area, the block area will not be used.

    By the way, it has little to do with large (or small) result sets, contrary to what azs0309 is saying.
    ---
    "It does not work" is not a valid problem statement.

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