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Date: Sat, 29 Mar 2025 08:09:11 -0700
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Subject: Re: Quesion about querying distributed databases
To: Kevin Stephenson <kjs714@hotmail.com>,
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 3/29/25 02:15, Kevin Stephenson wrote:
> Bumping this old thread to clarify a few points.
> 
> As an initial note on terminology, a "server" can be called a server, an 
> instance, a server instance, or in PostgreSQL's (PG hereafter) case, a 
> "DB Cluster." They all are used interchangeably in the wild to mean the 
> same thing, with perhaps "server" being the most ambiguous. And that 
> thing is a running process that is listening to (typically) a single 
> port and handing connections off to individual threads or processes (or 
> some other construct). The comments below use the word "instance" for 
> consistency and brevity.
> 
> MariaDB
> As mentioned by others, MariaDB (and MySQL proper, both hereafter 
> referred to as MySQL) instances only support a single database. The 
> CREATE DATABASE statement is a de facto synonym for CREATE SCHEMA (it is 
> disappointing that MySQL and MariaDB docs still do not mention this 
> significant fact). To disabuse those who believe MySQL support multiple 

Actually they do:

https://dev.mysql.com/doc/refman/9.2/en/create-database.html

"CREATE DATABASE creates a database with the given name. To use this 
statement, you need the CREATE privilege for the database. CREATE SCHEMA 
is a synonym for CREATE DATABASE."

https://mariadb.com/kb/en/create-database/

"CREATE DATABASE creates a database with the given name. To use this 
statement, you need the CREATE privilege for the database. CREATE SCHEMA 
is a synonym for CREATE DATABASE."

They don't expound on what that means in real terms.


> databases, query any of the INFORMATION_SCHEMA tables and for all those 
> that have the *_CATALOG column (CATALOG is a synonym for DATABASE), 
> notice every row in every table that shows a catalog column, they all 
> say "def", as in default. Further, the identifier used in CREATE 
> DATABASE will show up in INFORMATION_SCHEMA tables in *_SCHEMA columns.


-- 
Adrian Klaver
adrian.klaver@aklaver.com