Hi peng
> According to 8.4 document 44.1(Most system catalogs are
> copied from the template database during database creation and are
thereafter database
> -specific.),we know that each created database has their own pg_...
tables
I believe it is right.
> and thus if a superuser administrator wants to list all the tables
in all the
> databases,how do the postgresql interval implement it? will the
postgresql
> interval load all the pg_.... tables in all the databases to get
the final answer?
I think postgresql never interval load all the pg_.... tables in all
the databases.
If administrator want to list all the tables,we heve to create application.
ex.
oid2name -q | awk '{print$2}'|grep -v template0 |xargs -l1 oid2name -d
* oid2name is contrib module.
Thank you
hi,Kenichiro,
Thanks for your answer!
Then another question comes: According to 8.4 document 44.1(Most
system catalogs are copied from the template database during database
creation and are thereafter database-specific.),we know that each
created database has their own pg_... tables and thus if a superuser
administrator wants to list all the tables in all the databases,how do
the postgresql interval implement it? will the postgresql interval
load all the pg_.... tables in all the databases to get the final answer?
Thanks!
peng
2010/4/8 Kenichiro Tanaka <ketanaka@xxxxxxxxxxxxxx
<mailto:ketanaka@xxxxxxxxxxxxxx>>
Hello sunpeng
First,I answer this question.
>another question:how postgresql internal knows which
>relations belongs to which database?
When we use "psql" command ,it means "psql -d postgres".
#you can change default parameter to set PGDATABASE (OS parameter)
"-d" indicate your connecting database and this is the ANSWER.
So, it is natural that pg_class does not have "database" field.
We can not access other database with psql without using dblink.
I think we can display some database's pg_class with following
command,
============================================================
#DISPLAY "test" and "postgres"'s tables
#Your postgresql have to be installed dblink
#1)create dblink
select dblink_connect('test','host=postgres01 port=1843
dbname=test user=p843');
select dblink_connect('postgres','host=postgres01 port=1843
dbname=postgres user=p843');
#2) display
select 'test',* from dblink('test','select oid, relname from
pg_class') t1(oid oid, relname text)
union
select 'postgres',* from dblink('postgres','select oid, relname
from pg_class') t1(oid oid, relname text);
============================================================
Thank you
once i have created mydb and several relations in it,are there
any sql commands used to list all the tables in this mydb?
i noticed there are no database( pg_database.oid) field in
pg_class table,so i can not use
select relname from pg_class,pg_database where
pg_database.datname like 'mydb' and pg_class.database =
pg_database.oid;
anybody knows how to do it?
another question:how postgresql internal knows which relations
belongs to which database?
thanks
--
================================================
Kenichiro Tanaka
K.K.Ashisuto
http://www.ashisuto.co.jp/english/index.html
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Kenichiro Tanaka
K.K.Ashisuto
http://www.ashisuto.co.jp/english/index.html
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