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How does the HyperLogLog algorithm work?
...htforward way of doing it (having a set and adding elements to the set) it does this in an approximate way.
Before looking how the HyperLogLog algorithm does this, one has to understand why you need it. The problem with a straightforward way is that it consumes O(distinct elements) of space. Why th...
Rails and PostgreSQL: Role postgres does not exist
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This message pops up, when the database user does not exist. Compare the manual here.
Multiple local databases cannot be the explanation. Roles are valid cluster-wide. The manual again:
Note that roles are defined at the database cluster level, and so are
valid in...
Does Java read integers in little endian or big endian?
...n-API) way to map some bytes directly into an int in Java.
Every API that does this or something similar defines the behaviour pretty precisely, so you should look up the documentation of that API.
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“git diff” does nothing
...igure out where. Regular git commands appear to work fine, but "git diff" does nothing. To be safe, I removed external diff tools from my .gitconfig file. This was installed via MacPorts and is the lates version (1.7.2.2).
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Does IE9 support console.log, and is it a real function?
...is supported by all major browsers. I just spent a day working out why IE9 doesn't like my script and now I know why - it had a console.log in the very first step. Impossible to debug, since turning debug mode made this bug go away in an instant :P Thanks for clarification!!
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How to redirect to previous page in Ruby On Rails?
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doesn't having several tabs open confuse this logic?
– jones
Jan 22 '13 at 11:19
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Why does ASP.NET webforms need the Runat=“Server” attribute?
..., and HTML Tags have the option of either being runat="server" or not. It doesn't hurt anything to leave the tag in, and it causes a compiler error to take it out. The more things you imply about web language, the less easy it is for a budding programmer to come in and learn it. That's as good a ...
What does the filter parameter to createScaledBitmap do?
... I get the impression (though I'm glad to be corrected) that Android/Skia does simple subsampling when downsizing without filtering, so you are likely to get better results from filtering even when downsizing. (There's an alternate method for getting high quality downsizing with interpolation, inv...
strdup() - what does it do in C?
...d returns NULL immediately. Setting of errno to ENOMEM is something malloc does in POSIX so we don't need to explicitly do it in our strdup. If you're not POSIX compliant, ISO C doesn't actually mandate the existence of ENOMEM so I haven't included that here(b).
Otherwise the allocation worked so we...
Selecting empty text input using jQuery
...nction() { return this.value == ""; });
or
// WARNING: if input element does not have the "value" attribute or this attribute was removed from DOM then such selector WILL NOT WORK!
// For example input with type="file" and file does not selected.
// It's prefer to use "filter()" method.
// Thank...