when i logged in mydb, any sql command used to list all the tables in this mydb?

On Thu, Apr 8, 2010 at 6:34 PM, sunpeng <bluevaley@gmail.com> wrote:

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

hi,

You can use the -E option for psql, so it will output all querys
executed behind the scenes when you use meta-commands like \dt.
You can then copy and modify those querys to better suit your needs.

Example

$ psql -E mydb
psql (8.4.3)
Type "help" for help.

mydb=# \dt
.. (the query that gets executed is appears here)..

List of relations
Schema | Name | Type | Owner
--------+--------------------------+-------+--------
public | sometable | table | myname

HTH,

diego

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
================================================

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@ashisuto.co.jp>

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@ashisuto.co.jp
<mailto:ketanaka@ashisuto.co.jp>>

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
================================================