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Very large matrices using Python and NumPy
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PyTables and NumPy are the way to go.
PyTables will store the data on disk in HDF format, with optional compression. My datasets often get 10x compression, which is handy when dealing with tens or hundreds of millions of rows....
Is “double hashing” a password less secure than just hashing it once?
...broken with a pre-computed dictionary attack (for example, using a Rainbow Table). Otherwise, the attacker must spend time to compute a hash for each password and see if it matches the stored hash.
All passwords are not equally likely. Attackers might exhaustively search all short passwords, but th...
How to repair a serialized string which has been corrupted by an incorrect byte count length?
... will cause this error.
Solution: store serialized data into BLOB in your table.
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Why does calling a method in my derived class call the base class method?
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You can imagine, that a class, when instantiated, is nothing more than a table of pointers, pointing to the actual implementation of its methods. The following image should visualize this pretty well:
Now there are different ways, a method can be defined. Each behaves different when it is used ...
boost Composite keys - C/C++ - 清泛网 - 专注C/C++及内核技术
...lational databases, composite keys depend on two or more fields of a given table The analogous concept in Boost MultiIndex is Composite keys
In relational databases, composite keys depend on two or more fields of a given table. The analogous concept in Boost.MultiIndex is modeled by means of com...
Rails 3 migrations: Adding reference column?
...class AddUserToTester < ActiveRecord::Migration
def change
change_table :testers do |t|
t.references :user, index: true
end
end
def down
change_table :testers do |t|
t.remove :user_id
end
end
end
c.f.: http://apidock.com/rails/ActiveRecord/ConnectionAdapters...
Syntax of for-loop in SQL Server
...teger in their work (iterating from row to row or result to result in temp tables) and may be thrown off if the increment happens at the beginning of the cycle rather than the end.
– CSS
Feb 3 '16 at 15:22
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Avoid line break between html elements
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nobr is too unreliable, use tables
<table>
<tr>
<td> something </td>
<td> something </td>
</tr>
</table>
It all goes on the same line, everything is level with eachother,...
Command line CSV viewer? [closed]
...ropriate width of each column, and displays the text as a nicely formatted table.
Note: whenever you have empty fields, you need to put some kind of placeholder in it, otherwise the column gets merged with following columns. The following example demonstrates how to use sed to insert a placeholder:...
SQL Server Text type vs. varchar data type [closed]
...NTEXT. You'll need to enable large value types out of row for them with sp_tableoption if you want them to be always stored out of row.
As mentioned above and here, TEXT is going to be deprecated in future releases:
The text in row option will be removed in a future version of SQL Server. Avoid usi...