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Fast way to discover the row count of a table in PostgreSQL
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I did this once in a postgres app by running:
EXPLAIN SELECT * FROM foo;
Then examining the output with a regex, or similar logic. For a simple SELECT *, the first line of output should look something like this:
Seq Scan on uids (cost=0.00..1.21 rows=8 width=75)
You can use the rows=(\d...
What is the advantage of using abstract classes instead of traits?
...xtend, all the others get with, that's it. Think of with as a comma: class Foo extends Bar, Baz, Qux.
– Jörg W Mittag
May 20 '19 at 8:23
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Using the HTML5 “required” attribute for a group of checkboxes?
...h_payment_type_1" name="wish[payment_type][]" type="checkbox" value="1">Foo
</label>
</span>
<span class="checkbox payment-radio">
<label for="wish_payment_type_2">
<input class="check_boxes required" id="wish_payment_type_2" name="wish[payme...
Appending to an existing string
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You can use << to append to a string in-place.
s = "foo"
old_id = s.object_id
s << "bar"
s #=> "foobar"
s.object_id == old_id #=> true
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Plot a legend outside of the plotting area in base graphics?
...dianred"), pch=20)
Then add the legend
add_legend("topright", legend=c("Foo", "Bar"), pch=20,
col=c("steelblue", "indianred"),
horiz=TRUE, bty='n', cex=0.8)
Resulting in:
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impro...
Libraries not found when using CocoaPods with iOS logic tests
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Although this solution may create an error: Class Foo is implemented in both MyApp and MyAppTestCase. One of the two will be used. Which one is undefined. This seems to be caused by a bug in Cocoapods; see @JRV answer below.
– Richard
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How to determine the memory footprint (size) of a variable?
... is a bit hacky, but it should work.
$start_memory = memory_get_usage();
$foo = "Some variable";
echo memory_get_usage() - $start_memory;
Note that this is in no way a reliable method, you can't be sure that nothing else touches memory while assigning the variable, so this should only be used as ...
How do I call ::std::make_shared on a class with only protected or private constructors?
... A &operator =(const A &) = delete;
};
::std::shared_ptr<A> foo()
{
return A::create();
}
::std::shared_ptr<A> bar()
{
return A::create("George", 5);
}
::std::shared_ptr<A> errors()
{
::std::shared_ptr<A> retval;
// Each of these assignments to retval ...
How to get ID of the last updated row in MySQL?
...D of every row affected by an update statement:
SET @uids := null;
UPDATE footable
SET foo = 'bar'
WHERE fooid > 5
AND ( SELECT @uids := CONCAT_WS(',', fooid, @uids) );
SELECT @uids;
This will return a string with all the IDs concatenated by a comma.
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What does an underscore in front of an import statement mean?
...erface in your code like in the example:
db, err := sql.Open("sqlite3", "./foo.db")
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