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What is C collation?
The C collation is a simple set of rules that is available regardless of the database’s encoding, and the behavior should be consistent across encodings (which is made possible by only recognizing the US English alphabet — “a-z” and “A-Z” — as “letters”, and sorting by byte value, which should be the same for the …
What is collation type in MySQL?
A collation is a set of rules that defines how to compare and sort character strings. Each collation in MySQL belongs to a single character set. Every character set has at least one collation, and most have two or more collations. A collation orders characters based on weights. 1, “Collation Implementation Types”.
What does collation support do in PostgreSQL 9.1?
Collation Support The collation feature allows specifying the sort order and character classification behavior of data per-column, or even per-operation. This alleviates the restriction that the LC_COLLATE and LC_CTYPE settings of a database cannot be changed after its creation. 22.2.1.
When to use stripped collation names in PostgreSQL?
Use of the stripped collation names is recommendable, since it will make one less thing you need to change if you decide to change to another database encoding. Note however that the default, C, and POSIX collations can be used regardless of the database encoding.
Which is an equivalent of except in PostgreSQL?
Note that these differ from EXCEPT if the same tuple exists in both relations and contains null. Let a = { (1,1), (2,2), (1,null)} and b = { (1,1), (1,null)} In a sense, EXCEPT considers null to be equal to null, whereas the predicate a.c2 = b.c2 evaluates to null if either a.c2 or b.c2 is null and as a consequence NOT EXISTS evaluates to false.
Why is new collation not compatible with template database?
ERROR: new collation (en_NZ.utf8) is incompatible with the collation of the template database (en_US.UTF-8) HINT: Use the same collation as in the template database, or use template0 as template. That fails because there already could be some data in template1 which is not compatible with the locale specific in the create database command.