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Messages 1 to 6 of 6 total |
BlobBlockSize |
Sat, Jul 5 2008 9:39 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | It would help to keep filesizes down if the blockblocksize could be set on a column by column basis.
Roy Lambert |
Sun, Jul 6 2008 8:21 AM | Permanent Link |
Eryk Bottomley | Roy,
> It would help to keep filesizes down if the blockblocksize could be set on a column by column basis. If you want to do that then you can just bounce each column out so that it resides in its own BLB file. Eryk |
Sun, Jul 6 2008 9:07 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Eryk
That would work, but it would also mean maintaining the linkages which I know can be done with triggers and joining/setting up master-detail relationships and I would regard as sub-optimal. Roy Lambert |
Mon, Jul 7 2008 12:52 PM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Roy,
<< It would help to keep filesizes down if the blockblocksize could be set on a column by column basis. >> This will happen with the Enterprise Server. It can't happen with the existing version without using multiple files per BLOB (or sub-allocation, which is not optimal), and most people would be against more files. -- Tim Young Elevate Software www.elevatesoft.com |
Tue, Jul 8 2008 3:35 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Tim
OK I'll suffer the waste space then. Its not to bad as long as I use NULLs as well. What's sub-allocation? Roy Lambert |
Tue, Jul 8 2008 2:16 PM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Roy,
<< What's sub-allocation? >> It's allocating using a main block size, and then sub-allocating the main blocks into smaller block sizes. For example, you would have a table block size of 512, and then the columns could each have block sizes that are smaller than, but still a multiple of, the larger table block size. The reason that it gets messy is that you have to share the main blocks among multiple columns, so you can really experience some severe fragmentation that can kill any performance benefits that you might have been looking to gain. IOW, if you have to read 2 sub-allocated blocks in two different main blocks (think adding some BLOB column data, and then adding more data later to the same BLOB column), then you end up reading two main blocks with the sub-allocation design when you would have only had to read one main block with the existing design. -- Tim Young Elevate Software www.elevatesoft.com |
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