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Fastest way to count exact number of rows in a very large table?
...ECT COUNT(*) FROM TABLE_NAME will be slow when the table has lots of rows and lots of columns.
25 Answers
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Trying to understand CMTime and CMTimeMake
1) CMTimeMake(1,10) means duration of 1 second and timescale of 10, or 10 frames per second. This means 1s duration of video with 10 frames?
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Is there a reason that Swift array assignment is inconsistent (neither a reference nor a deep copy)?
I'm reading the documentation and I am constantly shaking my head at some of the design decisions of the language. But the thing that really got me puzzled is how arrays are handled.
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Maximum number of records in a MySQL database table
...utoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!
8 Answers
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passing several arguments to FUN of lapply (and others *apply)
...n the lapply call as an argument, like so:
lapply(input, myfun, arg1=6)
and lapply, recognizing that arg1 is not an argument it knows what to do with, will automatically pass it on to myfun. All the other apply functions can do the same thing.
An addendum: You can use ... when you're writing you...
How to track down a “double free or corruption” error
...You can set this from gdb by using the set environment MALLOC_CHECK_ 2 command before running your program; the program should abort, with the free() call visible in the backtrace.
see the man page for malloc() for more information
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Code coverage for Jest
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When using Jest 21.2.1, I can see code coverage at the command line and create a coverage directory by passing --coverage to the Jest script. Below are some examples:
I tend to install Jest locally, in which case the command might look like this:
npx jest --coverage
I assume (tho...
Fastest way to determine if record exists
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@Declan_K: seems like my magic sphere failed in this case and a column entitled as id isn't PK. So +1 to your advice.
– zerkms
Aug 7 '13 at 22:00
4
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Are GUID collisions possible?
...with the same GUID. I know that microsoft uses an algorithm to generate a random GUID that has an extremely low chance of causing collisons, but is a collision still possible?
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What does do?
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October 2015 Update
This answer was posted several years ago and now the question really should be should you even consider using the X-UA-Compatible tag on your site? with the changes Microsoft has made to its browsers (more on those below).
Depending upon what Microsoft browsers you...