Обсуждение: A few comparison terms just to be sure.
Hi everyone. For a long time I've been an Oracle developer and administrator but recently I became seduced by what I read about Postgresql. So I downloaded and installed a server and I'm reading the docs right now, ready to start practicing. Just to feel at home, I would like to make a few comparisons between oracle and postgresql and I hope somebody can confirm if I'm right or not. The questions: 1- What I know as an oracle database (a group of schemas), in postgresql is called a cluster. Is that right? 2- what I know as "schema", in postgresql is called a "database"? 3- Every user is the superuser of his own schema/database but is there a SYS/SYSMAN/SYSTEM (DBA) user who has access to all "databases"? I place where I can log in and control what everyone is doing? 4- What in Oracle is the SYSTEM/SYSAUX schema (where all oracle's own objects reside) is the "postgres" database (I didn't find this schema although I read about in the docs: chapter 16.2)? I know these are pretty simple question and I'm really thankful in advance for any comments. Regards. _________________________________________________________________ Regístrate en el nuevo Windows Live Messenger beta. http://imagine-msn.com/minisites/messenger/default.aspx?locale=es-ar
"Dale Cooper" <sa_dale_cooper@hotmail.com> writes: > The questions: > 1- What I know as an oracle database (a group of schemas), in postgresql is > called a cluster. Is that right? No. A group of schemas is a database, a group of databases is a cluster (a/k/a installation). I think the SQL-spec term for what we call a database is a "catalog"; not sure if Oracle uses that terminology. > 2- what I know as "schema", in postgresql is called a "database"? No, it's called a schema. (Or at least it is if Oracle uses the spec terminology.) > 3- Every user is the superuser of his own schema/database but is there a > SYS/SYSMAN/SYSTEM (DBA) user who has access to all "databases"? I place > where I can log in and control what everyone is doing? In the first place, an ordinary user isn't "the superuser" of anything; he may own a table or a schema or a database but that doesn't give him superuser privileges, only the ability to drop or modify that object. The OS user that created the installation is a true superuser --- the documentation always refers to this user as "postgres" but you don't necessarily have to run Postgres under that username. > 4- What in Oracle is the SYSTEM/SYSAUX schema (where all oracle's own > objects reside) is the "postgres" database (I didn't find this schema > although I read about in the docs: chapter 16.2)? Perhaps you are looking for the pg_catalog schema. See chapter 43 (system catalogs). regards, tom lane
>From: Tom Lane <tgl@sss.pgh.pa.us> >To: "Dale Cooper" <sa_dale_cooper@hotmail.com> >CC: pgsql-novice@postgresql.org >Subject: Re: [NOVICE] A few comparison terms just to be sure. Date: Sun, 01 >Jul 2007 17:54:38 -0400 > >"Dale Cooper" <sa_dale_cooper@hotmail.com> writes: > > The questions: > > 1- What I know as an oracle database (a group of schemas), in postgresql >is > > called a cluster. Is that right? > >No. A group of schemas is a database, a group of databases is a cluster >(a/k/a installation). I think the SQL-spec term for what we call a >database is a "catalog"; not sure if Oracle uses that terminology. > > > 2- what I know as "schema", in postgresql is called a "database"? > >No, it's called a schema. (Or at least it is if Oracle uses the spec >terminology.) > > > 3- Every user is the superuser of his own schema/database but is there a > > SYS/SYSMAN/SYSTEM (DBA) user who has access to all "databases"? I place > > where I can log in and control what everyone is doing? > >In the first place, an ordinary user isn't "the superuser" of anything; >he may own a table or a schema or a database but that doesn't give him >superuser privileges, only the ability to drop or modify that object. >The OS user that created the installation is a true superuser --- the >documentation always refers to this user as "postgres" but you don't >necessarily have to run Postgres under that username. > > > 4- What in Oracle is the SYSTEM/SYSAUX schema (where all oracle's own > > objects reside) is the "postgres" database (I didn't find this schema > > although I read about in the docs: chapter 16.2)? > >Perhaps you are looking for the pg_catalog schema. See chapter 43 >(system catalogs). > > regards, tom lane Thanks Tom for your time and really quick answer (it seems I need to keep up reading :)). Regards. _________________________________________________________________ MSN Amor: busca tu ½ naranja http://latam.msn.com/amor/