Re: Re[2]: directory name equal database name - Mailing list pgsql-interfaces

But why «FOO» and «foo» are different just for PostgreSQL? In other DBMS this not happend. Is it historical specific that difficult change?

I try ask in another way. If I will not rename dabases of existing PostgreSQL installation, but i configure PostgreSQL from the beggining, to make directory name equal to database name, or whatever existing installation or preparation before installation from zero i cant change this mechanism?ut 

I try put example for understanding. I use PostgreSQL as backend for another applications. This applications use many people for accounting, hrm, erp, etc. In my case this applications have one vendor, but in the same time they all are separated. I mean in Microsoft SQL Server application called «Accounting» as frontend for users equal to Microsoft SQL Server database name «Accounting» AND equal directory name of database «Accounting». In PostgreSQL the last one is named by OID. Its passable when we have 1-5 bases, not much time waste to understand which database i am looking for, but when its over 10 databases its become difficult support and administrate. As sysadmin i support many companies where i come as remote specialist from time to time. Sometime in companies happen this: server crashed, no one configure backup with pg_dump, left only directory with bases PostgreSQL where inside list of OID databases, over 100 OIDs directory name that nothing mean. Some databases not critical for work, so can be connected later, but some databases asking connect very fast. So when i have 100 databases i even dont know what i need to do for understanding which one of this databases are «Accounting» database for example. In Microsoft SQL Server this never happen, just because database equal directory name.
In this example abstractedly question, how to attach PostgreSQL database when have just directory left from PostgreSQL with databases after server crashed without backup. In Microsoft SQL Server i know how do it in 2 click. Maybe this last paragraph with question i should ask in another mail list, but thanks in advance if answer this too.

select datname,oid from pg_database where oid = 'oidfromfilename'

 

 

 

 

 

Вторник, 4 февраля 2020, 19:20 +03:00 от Tom Lane <tgl@sss.pgh.pa.us>:
 

squid ward <squidw@mail.ru> writes:
> Question is why directory name not equal as database name?

Because (1) it doesn't work for database names that aren't legal as
filenames (according to the none-too-well-standardized rules of your
particular filesystem); (2) SQL requires us to treat "FOO" and "foo"
as distinct names, but the filesystem might not; (3) renaming a database
is dangerous, as there's no way to make the directory rename action
atomic with commit of the system catalog updates; (4) renaming a database
causes problems for concurrent sessions that might be in the middle of
opening files in that database. And probably a few other reasons I
don't recall off the top of my head.

> Can i change it?

No.

regards, tom lane