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Why does PostgreSQL perform sequential scan on indexed column?
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If the SELECT returns more than approximately 5-10% of all rows in the table, a sequential scan is much faster than an index scan.
This is because an index scan requires several IO operations for each row (look up the row in the index, then retrieve the row from the heap). Whe...
How do I update zsh to the latest version?
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If you have Homebrew installed, you can do this.
# check the zsh info
brew info zsh
# install zsh
brew install --without-etcdir zsh
# add shell path
sudo vim /etc/shells
# add the following line into the very end of the file(/etc/shells)
/usr/loc...
Why does PEP-8 specify a maximum line length of 79 characters? [closed]
... and get on with writing good, consistently formatted code. Sure, no one really thinks that 79 is optimal, but there's no obvious gain in changing it to 99 or 119 or whatever your preferred line length is. I think the choices are these: follow the rule and find a worthwhile cause to battle for, or p...
CSS How to set div height 100% minus nPx
...28px;
left: 0px;
bottom: 0px;
right: 0px;
}
i tested this in all known browsers and is working fine. Are there any drawbacks using this way?
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Replace multiple characters in a C# string
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And \s is actually equivalent to [ \f\n\r\t\v] so you are including some stuff there that wasn't in the original question. Addtionally, the original question asks for Replace("\n\n", "\n") which your regex doesn't handle.
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Error in : object of type 'closure' is not subsettable
I was finally able to work out the code for my scraping . It seemed to be working fine and then all of a sudden when I ran it again, I got the following error message:
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Float vs Decimal in ActiveRecord
...r that is how the IEEE specification defines floats in binary format. Basically, it stores sign, fraction and exponent to represent a Float. It's like a scientific notation for binary (something like +1.43*10^2). Because of that, it is impossible to store fractions and decimals in Float exactly.
Th...
How to use MySQL DECIMAL?
...et in trouble if you use DOUBLE columns for financial data.
DOUBLE is actually just a double precision (64 bit instead of 32 bit) version of FLOAT. Floating point numbers are approximate representations of real numbers and they are not exact. In fact, simple numbers like 0.01 do not have an exact r...
What Product Flavor does Android Studio build by default in build.gradle?
...e , we notice that Android Studio builds the first one specified alphabetically. Is there a way to tell Android Studio to build and test only a specific product flavor during development?
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How to compare arrays in C#? [duplicate]
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@Orace: actually, Enumerable.SequenceEqual gives an exception if either argument is null.
– ToolmakerSteve
May 10 '16 at 22:08
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