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Re^3: DBI::SQLite slowness

by Anonymous Monk
on Sep 20, 2013 at 04:59 UTC ( #1054957=note: print w/replies, xml ) Need Help??


in reply to Re^2: DBI::SQLite slowness
in thread DBI::SQLite slowness

I imagine BrowserUk is using vec

See Re: vec overflow?, Re: searching a vector array, Re^2: Array vs. Hash for sparsely integer-indexed data (bit vectors)

This takes about 33MB of ram,

perl -e " my $f='' ; vec($f, 2**28,1)=1; "

I think that's marking as seen (as duplicate) the id 268435456 or 268_435_456

I think BrowserUk is probably assuming a minimum starting id, 268_435_456 is a lot of IDs :) 256MiB

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Re^4: DBI::SQLite slowness ( mini vec tutorial )
by Anonymous Monk on Sep 20, 2013 at 13:10 UTC

    Following up on Re: vec overflow? an adjustable example (mini vec tutorial)

    The @ in the output it produces is used for meaning of "@at", its not an actual array :) for example  0@[ 0][ 0] means the number zero is stored in the first(zero-th,0-th) seen_vecs string, and its the first bit of the string (0-th bit) ; neat how that works, id-zero is zero-th bit, is offset-th-ed-bit :)

    This can help with the vec syntax :) Bit::Vector::Minimal - Object-oriented vec wrapper

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[moritz]: seems there's a size limit for hostenum, and the error message just sucks
[vrk]: None, other than the location of the error: auto/NetAddr/IP/ _splitref.al
[vrk]: Aha, there's a reference to "bug report 82719" in NetAddr/IP.pm's sub _splitref.
[moritz]: wow, that's their idea of an "improved error message"
[moritz]: how about "This network is too large to enumerate all host addresses." or so?
[vrk]: Well, there's a call to notcontiguous() before the error, whose description is "counts the bit positions remaining in the mask when the rightmost '0's are removed"
[vrk]: Clear as mud!

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