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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
.... The "right", "left", "inner" and "outer" strings may be more amenable to SQL users.
The "both" and "not.both" strings are my best suggestion at the moment -- but someone may have better string suggestions for the inner join and exclusive join. (I'm not sure if "exclusive" is the right terminolog...
Grouping functions (tapply, by, aggregate) and the *apply family
...ly of functions. For me, ddply() was very intuitive as I was familiar with SQL aggregation functions. ddply() became my hammer for solving many problems, some of which could have been better solved with other commands.
– JD Long
Aug 17 '10 at 19:23
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Tactics for using PHP in a high-load site
...you measure and compare your changes.
For example, for many years, the MySQL query cache was the solution to all of our performance problems. If your site was slow, MySQL experts suggested turning the query cache on. It turns out that if you have a high write load, the cache is actually crippling....
Difference between CouchDB and Couchbase
...uments) and 'out-of-box' REST endpoints compared to CouchDB, CouchBase has sql like language i.e. N1QL ( sometimes pronounced a Nickel). This is one of the reason why I don't really like / recommend using the term 'NoSQL'. I personally like term 'Non-relational'.
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Optimise PostgreSQL for fast testing
I am switching to PostgreSQL from SQLite for a typical Rails application.
2 Answers
2
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Is either GET or POST more secure than the other?
... be covered in a single answer. You need to use HTTPS, HSTS, CSP, mitigate SQL injection, script injection (XSS), CSRF, and a gazillion of other things that may be specific to your platform (like the mass assignment vulnerability in various frameworks: ASP.NET MVC, Ruby on Rails, etc.). There is no ...
Where do you store your salt strings?
...rks as long as it stays secret (opposite to the salt). A typical attack is SQL-injection, when someone gains access to the database but not to the code, a pepper stored in the database will be useless then. Most BCrypt implementations will add the salt automatically to the resulting hash-value, so t...
What are some (concrete) use-cases for metaclasses?
...with it.
For other real-world examples, take a look at various ORMs, like sqlalchemy's ORM or sqlobject. Again, the purpose is to interpret defintions (here SQL column definitions) with a particular meaning.
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Difference between reduce and foldLeft/fold in functional programming (particularly Scala and Scala
... doesn't shuffle and doesn't use HashPartitioner.
import org.apache.spark.sql.SparkSession
/* Note: standalone (non-local) mode */
val master = "spark://...:7077"
val spark = SparkSession.builder.master(master).getOrCreate()
/* Note: deterministic order */
val rdd = sc.parallelize(Seq("a", "b"...
PHP parse/syntax errors; and how to solve them
... statement and variable.
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if ($var = pdo_query($sql) {
$result = …
The curly { brace does not open the code block, without closing the if expression with the ) closing parenthesis first.
Else does not expect conditions
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else ($var >= 0)
Solution: Remo...