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Rails migrations: self.up and self.down versus change
... For example, in your case what is the reverse operation of add_column to call when you rollback? Of course it's remove_column. What is the inverse of create_table? It's drop_table. So in these cases rails know how to rollback and define a down method is superfluous (you can see in the documentation...
How to hide databases that I am not allowed to access
... I connect to my Heroku - Postgresql database via pgAdmin3 , It lists all the tables (about 2600). Every time I open the pgAdmin3 I have to find my own database.
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Rails: Default sort order for a rails model?
...ow use Book.published.confirmed.
With this method, the query is not actually executed until actual results are needed (lazy evaluation), so 7 scopes could be chained together but only resulting in 1 actual database query, to avoid performance problems from executing 7 separate queries.
You can u...
PostgreSQL: Is it better to use multiple databases with one schema each, or one database with multip
... the same as a MySQL "database". Having many databases on a PostgreSQL installation can get problematic; having many schemas will work with no trouble. So you definitely want to go with one database and multiple schemas within that database.
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Automatic prune with Git fetch or pull
... work is over and I don't know, I won't do a git fetch --prune and eventually I will push back the deleted branch.
3 Answ...
About Python's built in sort() method
...mergesort that's still used in Java, and one can hope that Java will eventually switch to his recent port of timsort).
Some explanation of the Java port of timsort is here, the diff is here (with pointers to all needed files), the key file is here -- FWIW, while I'm a better C programmer than Java ...
SignalR: Why choose Hub vs. Persistent Connection?
...persistent connections.
From the highly up-voted comment below:
Partially correct. You can get topics or groups in persistent connections as well. The big difference is dispatching different types of messages. For example you have different kinds of messages and you want to send different kind...
Flattening a shallow list in Python [duplicate]
...st of iterables with a list comprehension, or failing that, what would you all consider to be the best way to flatten a shallow list like this, balancing performance and readability?
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Using .otf fonts on web browsers
...orking on a website that requires font trials online, the fonts I have are all .otf
2 Answers
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How many bytes does one Unicode character take?
...ing, it defines codepoints and a codepoint is a number, associated with usually a character. I say usually because there are concepts like combining characters. You may be familiar with things like accents, or umlauts. Those can be used with another character, such as an a or a u to create a new log...