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Lord Raiden is offline Lord Raiden
2009-07-30 , 12:36
Posts: 1,562 | Thanked: 349 times | Joined on Jun 2008
#1
Not sure if anyone else has already seen this or not, but I thought I'd toss this up here as an interesting observation. It appears that, while sqlite format is slightly slower than GDBM, the original format for MM, (not that I've noticed all that much of a difference) SQlite databases appear to be significantly smaller than their GDBM counterparts. I say that because I've got two databases, one GDBM, and one SQlite3, and the GDBM weights in at 1.6gb while the SQlite came in at just over 900mb for the same exact area! That's 700mb less space, even though it's the same number of tiles over the same area!

Anyone else seeing this? Before this I expected to have nearly a 13gb database covering the entire upper northwest. Now it looks like it'll be around 6gb max. That's really kinda cool. It makes me wonder if GDBM is naturally generating this extra bloat in the database, and if so, why?

Anywho, just an interesting observation.
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lma is offline lma
2009-07-30 , 12:44
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#2
Originally Posted by Lord Raiden View Post
It makes me wonder if GDBM is naturally generating this extra bloat in the database, and if so, why?
It probably leaves a lot of holes in the file, which normally wouldn't be an issue but on FAT wastes space.
 
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Lord Raiden is offline Lord Raiden
2009-07-30 , 14:35
Posts: 1,562 | Thanked: 349 times | Joined on Jun 2008
#3
Well, that's the thing. I was seeing that "bloat" on not just fat file systems, but also Ext3 and UFS file systems.
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lma is offline lma
2009-07-30 , 17:50
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#4
Originally Posted by Lord Raiden View Post
I was seeing that "bloat" on not just fat file systems, but also Ext3 and UFS file systems.
How are you checking? ls(1) will show the full length of the file (including holes), but du(1) will show the actual space it uses on the filesystem:

Code:
Nokia-N800-43-7:/mnt/tmp# dd if=/dev/zero of=test bs=1024 count=1 seek=1024
1+0 records in
1+0 records out
Nokia-N800-43-7:/mnt/tmp# ls -l test
-rw-r--r--    1 root     root      1049600 Jul 30 18:46 test
Nokia-N800-43-7:/mnt/tmp# du test
8	test
Last edited by lma; 2009-08-02 at 08:58.
 

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