I seem to have some sort of phantom table in Postgres.
Suppose I do the following:
select * from information_schema.tables where table_schema = 'public';
I get:
table_name | table_type | ...
phantom_table BASE TABLE
...
So, I run:
drop table phantom_table cascade;
And I get:
ERROR: table "phantom_table" does not exist
Things I've tried:
Checking for spelling errors and making sure the schema is correct (I've even copied/pasted table name out of information schema query results).
vacuum
Reconnecting.
Killing other running processes from my user (nobody else is using the DB).
Checking for active locks on the table (there aren't any).
Anybody have any other ideas for things I should try?
You probably have some white space at the end of the name.
The easiest way is to let the format() function generate you the correct table name and statement:
select format('drop table %I.%I;', table_schema, table_name) as drop_statement
from information_schema.tables
where table_schema = 'public'
and table_name like '%phantom%';
Edit: it seems that psql on Windows isn't able to handle an identifier with a new line in a drop statement (it does when creating the table however).
To workaround that, you can use a DO block:
do
$$
declare
l_stmt text;
begin
select format('drop table %I.%I;', table_schema, table_name) as drop_statement
into l_stmt
from information_schema.tables
where table_schema = 'public'
and table_name like '%phantom%';
execute l_stmt;
end;
$$
;
Note this code assumes that only a single table with that name exists.
Related
I want to truncate the whole database while maintaining the sequence identity. I came up with something like this:
WITH tables_to_be_truncated AS (
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
AND table_name NOT IN ('admins', 'admin_roles')
)
TRUNCATE TABLE (SELECT table_name FROM tables_to_be_truncated) CONTINUE IDENTITY RESTRICT;
I get this error:
ERROR: syntax error at or near "TRUNCATE"
LINE 9: TRUNCATE TABLE (SELECT table_name FROM tables_to_be_truncated...
I do have the permissions to truncate the tables and when I run for a single table like TRUNCATE TABLE access_tokens it works fine.
I also tried with this
TRUNCATE TABLE (SELECT string_agg(table_name, ', ') FROM tables_to_be_truncated) CONTINUE IDENTITY RESTRICT
which didn't work as well.
From what I see in other posts, people are doing it with functions. I didn't want to go down this path honestly but if this is the only way...
You don't need a function for that. An anonymous code block will do:
DO $$
DECLARE row RECORD;
BEGIN
FOR row IN SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
AND table_name NOT IN ('admins', 'admin_roles')
LOOP
EXECUTE format('TRUNCATE TABLE %I CONTINUE IDENTITY RESTRICT;',row.table_name);
END LOOP;
END;
$$;
Other than that I don't think you'll be able to run dynamic queries with pure SQL.
Demo: db<>fiddle
I have created the following function to truncate bunch of tables starting with "irm_gtresult". There are no syntax errors in my function, but the function doesn't truncate the tables when I run it. What could be wrong here?
My Postgres db version is 8.4.
create or replace function br()
RETURNS void
LANGUAGE plpgsql
AS
$$
DECLARE
row text;
BEGIN
FOR row IN
select table_name from information_schema.tables where table_name ILIKE 'irm_gtresult%'
LOOP
EXECUTE 'TRUNCATE TABLE ' || row;
END LOOP;
END;
$$;
Call:
select br();
Your code is valid. I tested and it works for me in Postgres 9.4.
Using the outdated and unsupported version 8.4 (like you added) may be the problem. The version is just too old, consider upgrading to a current version.
However, I have a couple of suggestions:
Don't use key word row as variable name.
You don't need to loop, you can TRUNCATE all tables in a single command. Faster, shorter.
You may need to add CASCADE if there are dependencies. Be aware of the effect.
CREATE OR REPLACE FUNCTION br()
RETURNS void AS
$func$
BEGIN
EXECUTE (
SELECT 'TRUNCATE TABLE '
|| string_agg(format('%I.%I', schemaname, tablename), ',')
|| ' CASCADE'
FROM pg_tables t
WHERE tablename ILIKE 'irm_gtresult%'
AND schemaname = 'public'
-- AND tableowner = 'postgres' -- optionaly restrict to one user
);
END
$func$ LANGUAGE plpgsql;
Call:
SELECT br();
I am using the view pg_tables from the system catalog. You can as well use information_schema.tables like you did. Note the subtle differences:
How to check if a table exists in a given schema
Related answers with more explanation:
Can I truncate tables dynamically?
Truncating all tables in a Postgres database
To truncate in postgres you just have to use the TRUNC() function.
Example:
SELECT TRUNC(price, 0) AS truncated_price
FROM product;
I'm trying to create a multi tenent app using Symfony 2.6 and PostgreSQL schemas (namespaces). I would like to know how can I change some entity schema on the pre persist event?
I know that it's possible to set the schema as annotation #Table(schema="schema") but this is static solution I need something more dynamic!
The purpose using PostgreSQL is take advantage of schemas feature like:
CREATE TABLE tenant_1.users (
# table schema
);
CREATE TABLE tenant_2.users (
# table schema
);
So, if I want only users from tenant_2 my query will be something like SELECT * FROM tenant_2.users;
This way my data will be separated and I will have only one database to connect and maintain.
$schema = sprintf('tenant_%d', $id);
$em->getConnection()->exec('SET search_path TO ' . $schema);
You might also want to involve PostgreSQL's row level security instead - that way you can actually prevent the tenant from accessing the data, not just hiding it by prefixing a schema path.
Check this one out: https://www.tangramvision.com/blog/hands-on-with-postgresql-authorization-part-2-row-level-security. I just set a working tenant separation with the information on that page and I'm quite excited about it.
In my case, my tenants are called organisations, and some (not all) tables have an organisation_id that permanently binds a row to it.
Here is a version of my script I run during a schema update, which finds all tables with column organisation_id and enables the row level security with a policy that only shows rows that an org owns, if the org role is set:
CREATE ROLE "org";
-- Find all tables with organisation_id and enable the row level security
DO $$ DECLARE
r RECORD;
BEGIN
FOR r IN (
SELECT
t.table_name, t.table_schema, c.column_name
FROM
information_schema.tables t
INNER JOIN
information_schema.columns c ON
c.table_name = t.table_name
AND c.table_schema = t.table_schema
AND c.column_name = 'organisation_id'
WHERE
t.table_type = 'BASE TABLE'
AND t.table_schema != 'information_schema'
AND t.table_schema NOT LIKE 'pg_%'
) LOOP
EXECUTE 'ALTER TABLE ' || quote_ident(r.table_schema) || '.' || quote_ident(r.table_name) || ' ENABLE ROW LEVEL SECURITY';
EXECUTE 'DROP POLICY IF EXISTS org_separation ON ' || quote_ident(r.table_schema) || '.' || quote_ident(r.table_name);
EXECUTE 'CREATE POLICY org_separation ON ' || quote_ident(r.table_schema) || '.' || quote_ident(r.table_name) || 'FOR ALL to org USING (organisation_id = substr(current_user, 5)::int)';
END LOOP;
END $$;
-- Grant usage on all tables in all schemas to the org role
DO $do$
DECLARE
sch text;
BEGIN
FOR sch IN (
SELECT
schema_name
FROM
information_schema.schemata
WHERE
schema_name != 'information_schema'
AND schema_name NOT LIKE 'pg_%'
) LOOP
EXECUTE format($$ GRANT USAGE ON SCHEMA %I TO org $$, sch);
EXECUTE format($$ GRANT SELECT, UPDATE ON ALL SEQUENCES IN SCHEMA %I TO org $$, sch);
EXECUTE format($$ GRANT SELECT, UPDATE, INSERT, DELETE ON ALL TABLES IN SCHEMA %I TO org $$, sch);
EXECUTE format($$ ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT SELECT, UPDATE ON SEQUENCES TO org $$, sch);
EXECUTE format($$ ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT INSERT, SELECT, UPDATE, DELETE ON TABLES TO org $$, sch);
END LOOP;
END;
$do$;
Step two, when I create a new organisation, I also create a role for it:
CREATE ROLE "org:86" LOGIN;
GRANT org TO "org:86";
Step three, at the beginning of every request that should be scoped to a particular organisation, I call SET ROLE "org:86"; to enable the restrictions.
There is much more happening around what we do with all of this, but the code above should be complete enough to help people get started.
Good luck!
In Postgres, you can link to your other databases using dblink like so:
SELECT *
FROM dblink (
'dbname=name port=1234 host=host user=user password=password',
'select * from table'
) AS users([insert each column name and its type here]);
But this is quite verbose.
I've shortened it up by using dblink_connect and dblink_disconnect to abstract the connection string from my dblink queries. However, that still leaves me with the manual table definition (i.e., [insert each column name and its type here]).
Instead of defining the table manually, is there a way I can define it with a TYPE or anything else that'd be re-usable?
In my case, the number of remote tables I have to join and the number of columns involved makes my query massive.
I tried something along the lines of:
SELECT *
FROM dblink (
'myconn',
'select * from table'
) AS users(postgres_pre_defined_type_here);
But I received the following error:
ERROR: a column definition list is required for functions returning "record"
As you considered creating several types for dblink, you can accept creating several functions as well. The functions will be well defined and very easy to use.
Example:
create or replace function dblink_tables()
returns table (table_schema text, table_name text)
language plpgsql
as $$
begin
return query select * from dblink (
'dbname=test password=mypassword',
'select table_schema, table_name from information_schema.tables')
as tables (table_schema text, table_name text);
end $$;
select table_name
from dblink_tables()
where table_schema = 'public'
order by 1
Is there any query available to list all tables in my Postgres DB.
I tried out one query like:
SELECT table_name FROM information_schema.tables
WHERE table_schema='public'
But this query returns views also.
How can i get only table names only, not views?
What bout this query (based on the description from manual)?
SELECT table_name
FROM information_schema.tables
WHERE table_schema='public'
AND table_type='BASE TABLE';
If you want list of database
SELECT datname FROM pg_database WHERE datistemplate = false;
If you want list of tables from current pg installation of all databases
SELECT table_schema,table_name FROM information_schema.tables
ORDER BY table_schema,table_name;
Open up the postgres terminal with the databse you would like:
psql dbname (run this line in a terminal)
then, run this command in the postgres environment
\d
This will describe all tables by name. Basically a list of tables by name ascending.
Then you can try this to describe a table by fields:
\d tablename.
Hope this helps.
Try this:
SELECT table_name
FROM information_schema.tables
WHERE table_schema='public' AND table_type='BASE TABLE'
this one works!
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public';
For MySQL you would need table_schema='dbName' and for MSSQL remove that condition.
Notice that "only those tables and views are shown that the current user has access to". Also, if you have access to many databases and want to limit the result to a certain database, you can achieve that by adding condition AND table_catalog='yourDatabase' (in PostgreSQL).
If you'd also like to get rid of the header showing row names and footer showing row count, you could either start the psql with command line option -t (short for --tuples-only) or you can toggle the setting in psql's command line by \t (short for \pset tuples_only). This could be useful for example when piping output to another command with \g [ |command ].
How about giving just \dt in psql? See https://www.postgresql.org/docs/current/static/app-psql.html.
select
relname as table
from
pg_stat_user_tables
where schemaname = 'public'
This will not work if track_activities is disabled
select
tablename as table
from
pg_tables
where schemaname = 'public'
Read more about pg_tables