On Sun, Aug 8, 2010 at 6:50 PM, Martin Pitt martin.pitt@ubuntu.com wrote:
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As far as I know you can append files; I'm not sure about "inline" deletion, but even if it would exist, then over time (i. e. upgrades) you would dramatically fragment the file, which reduces or even reverts the initial space saving.
Fortunately fragmentation is not a problem: tar --delete squashes the deleted entry out of the file by rewriting the entire file contents from the point where the deletion occurred ;) Of course, that could be a bit slow, especially if you delete something near the start of the archive...
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On Fri, Aug 6, 2010 at 7:50 PM, Loïc Minier loic.minier@linaro.org wrote: [...]
Yup, Martin Pitt worked on some APT patches to allow keeping these compressed in the local disk.
Out of interest, since these indexes are designed to be used via mmap, do we need to decompress the files when running apt? If so, that suggests that the transient disk footprint actually increases, since we must store both the compressed and decompressed indexes (in addition to any package files apt then downloads). Alternatively apt could stream the data in and store it in memory, though that would raise the ram/swap footprint significantly compared with mmap.
Cheers ---Dave