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Concurrent vs serial queues in GCD

... First, it's important to know the difference between threads and queues and what GCD really does. When we use dispatch queues (through GCD), we're really queueing, not threading. The Dispatch framework was designed specifically to get us away from thr...
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PostgreSQL: Drop PostgreSQL database through command line [closed]

...elect * from pg_stat_activity;" say? Are the other users besides yourself now connected? If so, you might have to edit your pg_hba.conf file to reject connections from other users, or shut down whatever app is accessing the pg database to be able to drop it. I have this problem on occasion in pro...
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mmap() vs. reading blocks

...able length records. I've got a first implementation up and running and am now looking towards improving performance, particularly at doing I/O more efficiently since the input file gets scanned many times. ...
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SQL, Postgres OIDs, What are they and why are they useful?

... if you don't know what OIDs are used for then you probably don't want to be using them. – vdegenne Jul 9 '16 at 21:26 ...
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How to assign the output of a command to a Makefile variable

...converts my tab into a number of spaces. You, frustrated internet citizen, now copy this, thinking that you now have the same text that I used. The make command, now reads the spaces and finds that the "all" command is incorrectly formatted. So copy the above text, paste it, and then convert the whi...
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Benefits of EBS vs. instance-store (and vice-versa) [closed]

...cost...? Also, is there any metric as to whether more people are using EBS now that it's available, considering it is still relatively new? ...
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“Warning: iPhone apps should include an armv6 architecture” even with build config set

...ode 4.5 or higher, which no longer supports armv6.) That's it. You should now be able to build/archive without generating errors. If it still doesn't work, see this answer from justinxreese, which suggests adding entries for armv6 and armv7 under "Required Device Capabilities" in your info.plist f...
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Specifying column name in a “references” migration

... Do it manually: add_column :post, :author_id, :integer but now, when you create the belongs_to statement, you will have to modify it, so now you have to call def post belongs_to :user, :foreign_key => 'author_id' end ...
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Determine on iPhone if user has enabled push notifications

... hear their response on this issue. How can we develop great apps without knowing such basic info?? – Oded Regev Mar 21 '13 at 11:59 15 ...
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Unknown file type MIME?

... You can use application/octet-stream for unknown types. RFC 2046 states in section 4.5.1: The "octet-stream" subtype is used to indicate that a body contains arbitrary binary data. sh...