| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | ZongtianHou <zongtianhou(at)icloud(dot)com> |
| Cc: | pgsql-admin <pgsql-admin(at)postgresql(dot)org> |
| Subject: | Re: Schema and Namespace Oid confusion |
| Date: | 2018-12-28 15:36:14 |
| Message-ID: | 201812281536.wlr7arvxlfsk@alvherre.pgsql |
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| Thread: | |
| Lists: | pgsql-admin |
Hello
On 2018-Dec-28, ZongtianHou wrote:
> I get somehow confused when I learn about namespace here, there are two questions,
> First, what is the difference between namespace and schema?
None. Schema is the user-visible name for the feature; namespace is the
source code and system catalog level.
> Second, why the Oid of public namespace is 2200, the same between
> databases?
Not necessarily. That's the initial value, but it's possible to drop
the public schema and create it afresh.
> Does oid is unique for every object across cluster?
No, only inside each individual catalog are OIDs guaranteed unique.
> Does someone know about these clearly?
Yes.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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