a very naive question about table names in Postgres

I know that on my Mac the tables are kept in the data directory

/Users/martinmueller/Library/Application Support/Postgres/var-13. If I go
there I see that internally the tables have numbers. Somewhere in the
system there must be a table that maps the name I gave to table X to the
numerical inside the database.

Check the pg_class table in the system catalog. The numeric value is the
OID.

https://www.postgresql.org/docs/14/catalog-pg-class.html

Craig

On 1/01/22 09:27, Martin Mueller wrote:

I have a very naïve question and don’t know where tp  look for the
answer.  I use Postgres via AquaData Studio as a giant spreadsheet.  I
create tables and give them names. I see the table names  and know how
to manipulate them with simple SQL queries.

I know that on my Mac the tables are  kept in the  data directory
/Users/martinmueller/Library/Application Support/Postgres/var-13.  If
I go there I see that internally the tables have numbers.  Somewhere
in the system there must be a table that maps the name I gave to table
X  to the numerical  inside the database.

Where is that mapping and how can I query it?  On what page of the
documentation do I find the answer?

I much prefer Postgres to Mysql for  a variety of reasons, but mostly
for its elegant string functions. But in Mysql it seems to be much
easier to keep track of tables.

Martin Mueller

Professor emeritus of English and Classics

Northwestern University

Hi Martin.

Don't know why you want the information you appear to be asking!

However, if you are up to learning how to use psql from the command
line, then you have an extremely powerful tool to use to query and
manipulate tables in PostgreSQL!  I set up SQL in text files and get
psql to execute them (\i my_query.sql) -- you can execute SQL directly
in psql, but that is really only good for very simply queries.  I find
that using psql & a text editor a lot easier than using a GUI based tool.

Cheers,
Gavin

I know that on my Mac the tables are kept in the data directory

/Users/martinmueller/Library/Application Support/Postgres/var-13. If I go
there I see that internally the tables have numbers. Somewhere in the
system there must be a table that maps the name I gave to table X to the
numerical inside the database.

Check the pg_class table in the system catalog. The numeric value is the
OID.

https://www.postgresql.org/docs/14/catalog-pg-class.html

Craig

Whoops, spoke too soon. I believe it's actually the relfilenode value that
you want.

Craig

Am Fri, Dec 31, 2021 at 08:27:59PM +0000 schrieb Martin Mueller:

I much prefer Postgres to Mysql for a variety of reasons,
but mostly for its elegant string functions. But in Mysql it
seems to be much easier to keep track of tables.

May I ask for the context of "keep track of tables" ?

Karsten
--
GPG 40BE 5B0E C98E 1713 AFA6 5BC0 3BEA AC80 7D4F C89B

pá 31. 12. 2021 v 21:28 odesílatel Martin Mueller
<martinmueller@northwestern.edu> napsal:

I have a very naïve question and don’t know where tp look for the answer. I use Postgres via AquaData Studio as a giant spreadsheet. I create tables and give them names. I see the table names and know how to manipulate them with simple SQL queries.

I know that on my Mac the tables are kept in the data directory /Users/martinmueller/Library/Application Support/Postgres/var-13. If I go there I see that internally the tables have numbers. Somewhere in the system there must be a table that maps the name I gave to table X to the numerical inside the database.

Where is that mapping and how can I query it? On what page of the documentation do I find the answer?

There is a nice blogpost related.
https://www.2ndquadrant.com/en/blog/postgresql-filename-to-table/

On 12/31/21 12:27 PM, Martin Mueller wrote:

I know that on my Mac the tables are �kept in the �data directory
/Users/martinmueller/Library/Application Support/Postgres/var-13.� If I
go there I see that internally the tables have numbers.� Somewhere in
the system there must be a table that maps the name I gave to table X
to the numerical� inside the database.

Where is that mapping and how can I query it?� On what page of the
documentation do I find the answer?

Dear Prof. Mueller,

This question strikes Postgres people a bit like your teenager asking
where you keep the tallest ladder. There aren't many practical uses for
accessing these files directly, and if you do it's likely to break your
database. Could you speak a bit more about your goal here? Perhaps
someone can suggest a good way to achieve it.

Yours,

--
Paul ~{:-)
pj@illuminatedcomputing.com

On Fri, 31 Dec 2021 at 16:25, Paul Jungwirth <pj@illuminatedcomputing.com>
wrote:

On 12/31/21 12:27 PM, Martin Mueller wrote:

I know that on my Mac the tables are kept in the data directory
/Users/martinmueller/Library/Application Support/Postgres/var-13. If I
go there I see that internally the tables have numbers. Somewhere in
the system there must be a table that maps the name I gave to table X
to the numerical inside the database.

Where is that mapping and how can I query it? On what page of the
documentation do I find the answer?

Dear Prof. Mueller,

Everything you ever wanted to know is here

PostgreSQL: Documentation: 14: Chapter 52. System Catalogs
<https://www.postgresql.org/docs/14/catalogs.html&gt;

Enjoy the journey

Dave