I have a partitioned table out of main table using range.
CREATE TABLE public.partition1 PARTITION OF public.maintable
FOR VALUES FROM ('2017-01-01 00:00:00') TO ('2050-01-01 00:00:00')
How can i get the Values range information using a query to postgres.
I have used a query that at least gives me information for the main and partitioned tables, but i cannot seem to find a way to access the value range
FROM ('2017-01-01 00:00:00') TO ('2050-01-01 00:00:00')
assigned to table partition1
Query used to get partition table information
WITH RECURSIVE partition_info
(relid,
relname,
relsize,
relispartition,
relkind) AS
(
(SELECT oid AS relid,
relname,
pg_relation_size(oid) AS relsize,
relispartition,
relkind
FROM pg_catalog.pg_class
WHERE relname = 'completedorders' AND
relkind = 'p')
UNION ALL
(SELECT
c.oid AS relid,
c.relname AS relname,
pg_relation_size(c.oid) AS relsize,
c.relispartition AS relispartition,
c.relkind AS relkind
FROM partition_info AS p,
pg_catalog.pg_inherits AS i,
pg_catalog.pg_class AS c
WHERE p.relid = i.inhparent AND
c.oid = i.inhrelid AND
c.relispartition = true)
)
SELECT * FROM partition_info;
The following query provides the information about partitions as well. From there on its just string manipulation in order to get further information.
Note: you will have to change the name of the table in the query.
with recursive inh as (
select i.inhrelid, null::text as parent
from pg_catalog.pg_inherits i
join pg_catalog.pg_class cl on i.inhparent = cl.oid
join pg_catalog.pg_namespace nsp on cl.relnamespace = nsp.oid
where nsp.nspname = 'public' ---<< change table schema here
and cl.relname = 'tablename' ---<< change table name here
union all
select i.inhrelid, (i.inhparent::regclass)::text
from inh
join pg_catalog.pg_inherits i on (inh.inhrelid = i.inhparent)
)
select c.relname as partition_name,
n.nspname as partition_schema,
pg_get_expr(c.relpartbound, c.oid, true) as partition_expression,
pg_get_expr(p.partexprs, c.oid, true) as sub_partition,
parent,
case p.partstrat
when 'l' then 'LIST'
when 'r' then 'RANGE'
end as sub_partition_strategy
from inh
join pg_catalog.pg_class c on inh.inhrelid = c.oid
join pg_catalog.pg_namespace n on c.relnamespace = n.oid
left join pg_partitioned_table p on p.partrelid = c.oid
order by n.nspname, c.relname
I am trying to user a trigger to return the 'data_type' of a column from my table. SQL FIDDLE has the whole trigger...but the ket bits are:
FOR each_column IN
SELECT
attname as column_name,
format_type(atttypid, atttypmod) AS data_type
FROM
pg_attribute
WHERE
attrelid =
(
SELECT
oid
FROM
pg_class
WHERE
relname = tg_relname
LIMIT 1 )
AND attnum > 0
LOOP
The error I am getting (at the end of this query is):
ERROR: column "data_type" of relation does not exist Where: PL/pgSQL function log.insert_history() line 94 at SQL statement
I'm not sure what I'm missing...does anyone see it?
You can use SQL below to get all columns from table YOUR_SCHEMA.YOUR_TABLE_NAME:
SELECT
a.attname, LOWER(format_type(a.atttypid, a.atttypmod)) AS type, d.adsrc,
a.attnotnull, a.atthasdef
FROM
pg_attribute a
LEFT JOIN pg_attrdef d ON (a.attrelid = d.adrelid AND a.attnum = d.adnum)
WHERE
a.attnum > 0 AND NOT a.attisdropped
AND a.attrelid = (SELECT oid FROM pg_catalog.pg_class WHERE relname = 'YOUR_TABLE_NAME'
AND relnamespace = (SELECT oid FROM pg_catalog.pg_namespace WHERE nspname = 'YOUR_SCHEMA'))
ORDER BY
a.attnum;
#Abelisto was correct - I forgot to add the statement in 'create table'. Oops!
Working solution in SQL FIDDLE is HERE.
I'm running a project on a Postgres database and need to retrieve the comments on columns within the DB to be used as table headings and such. I have seen that there are a couple of built in functions (pg_description and col_description) but i haven't been able to find examples on how to use them and playing around with them has proved pretty futile.
So I was wondering if any has been able to do this before and if so, how?
select
c.table_schema,
c.table_name,
c.column_name,
pgd.description
from pg_catalog.pg_statio_all_tables as st
inner join pg_catalog.pg_description pgd on (
pgd.objoid = st.relid
)
inner join information_schema.columns c on (
pgd.objsubid = c.ordinal_position and
c.table_schema = st.schemaname and
c.table_name = st.relname
);
It all works by oid,
mat=> SELECT c.oid FROM pg_catalog.pg_class c WHERE c.relname = 'customers';
oid
-------
23208
(1 row)
Now, I have the oid for that table, so I can ask :
mat=> select pg_catalog.obj_description(23208);
obj_description
-------------------
Customers
(1 row)
Then, I can ask for the description of the fourth column :
mat=> select pg_catalog.col_description(23208,4);
col_description
-----------------------------------------
Customer codes, CHS, FACTPOST, POWER...
(1 row)
If you want to know which queries does psql run when you do \dt+ or \d+ customers, just run it with -E.
Just to be here if somebody will need it.
There are many answers here, but none of them was as simple as I would like it to be. So, based on previous answers and current postgres 9.4, I have created this query:
SELECT
obj_description(format('%s.%s',isc.table_schema,isc.table_name)::regclass::oid, 'pg_class') as table_description,
pg_catalog.col_description(format('%s.%s',isc.table_schema,isc.table_name)::regclass::oid,isc.ordinal_position) as column_description
FROM
information_schema.columns isc
It fetches table and column descriptions, without any confusing joins and ugly string concatenations.
Take care with schemas, this code considers them:
SELECT
cols.column_name, (
SELECT
pg_catalog.col_description(c.oid, cols.ordinal_position::int)
FROM
pg_catalog.pg_class c
WHERE
c.oid = (SELECT ('"' || cols.table_name || '"')::regclass::oid)
AND c.relname = cols.table_name
) AS column_comment
FROM
information_schema.columns cols
WHERE
cols.table_catalog = 'your_database'
AND cols.table_name = 'your_table'
AND cols.table_schema = 'your_schema';
References:
Postgresql Document Table and Column Description Comments on Table and Column
Determining the OID of a table in Postgres 9.1?
A slight change to one of the other answers which only gives you columns that have comments on them, this gives you all columns whether they have a comment or not.
select c.table_schema, st.relname as TableName, c.column_name,
pgd.description
from pg_catalog.pg_statio_all_tables as st
inner join information_schema.columns c
on c.table_schema = st.schemaname
and c.table_name = st.relname
left join pg_catalog.pg_description pgd
on pgd.objoid=st.relid
and pgd.objsubid=c.ordinal_position
where st.relname = 'YourTableName';
This works for me using the PostBooks 3.2.2 DB:
select cols.column_name,
(select pg_catalog.obj_description(oid) from pg_catalog.pg_class c where c.relname=cols.table_name) as table_comment
,(select pg_catalog.col_description(oid,cols.ordinal_position::int) from pg_catalog.pg_class c where c.relname=cols.table_name) as column_comment
from information_schema.columns cols
where cols.table_catalog='postbooks' and cols.table_name='apapply'
Regards,
Sylnsr
If you just need to show the comments for your columns among other data, you can also use:
\d+ my_table
Enhance for #Nick and #mat suggestions: use
SELECT obj_description('schemaName.tableName'::regclass, 'pg_class');
when you have string name (not oid).
To avoid to remember 'pg_class' parameter, and to avoid ugly concatenations at the function calls, as (tname||'.'||schema)::regclass, an useful overload for obj_description:
CREATE FUNCTION obj_description(
p_rname text, p_schema text DEFAULT NULL,
p_catalname text DEFAULT 'pg_class'
) RETURNS text AS $f$
SELECT obj_description((CASE
WHEN strpos($1, '.')>0 OR $2 IS NULL OR $2='' THEN $1
ELSE $2||'.'||$1
END)::regclass, $3);
$f$ LANGUAGE SQL IMMUTABLE;
-- USAGE: obj_description('mytable')
-- SELECT obj_description('s.t');
-- PS: obj_description('s.t', 'otherschema') is a syntax error,
-- but not generates exception: returns the same as ('s.t')
Now is easy to use, because the table name (rname parameter) is a varchar and can be expressed with a separated field for schema name, as in the main tables and queries.
See also "Getting list of table comments in PostgreSQL" or the new pg9.3 Guide
This answer is a little late, but it popped up on a google search I did to research this problem. We only needed Table descriptions, but the method would be the same for columns.
The column descriptions are in the pg_description table also, referenced by objoid.
Add this view:
CREATE OR REPLACE VIEW our_tables AS
SELECT c.oid, n.nspname AS schemaname, c.relname AS tablename, d.description,
pg_get_userbyid(c.relowner) AS tableowner, t.spcname AS "tablespace",
c.relhasindex AS hasindexes, c.relhasrules AS hasrules, c.reltriggers > 0 AS hastriggers
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
LEFT JOIN pg_tablespace t ON t.oid = c.reltablespace
LEFT JOIN pg_description d ON c.oid = d.objoid
WHERE c.relkind = 'r'::"char";
ALTER TABLE our_tables OWNER TO postgres;
GRANT SELECT, UPDATE, INSERT, DELETE, REFERENCES, TRIGGER ON TABLE our_tables TO postgres;
GRANT SELECT ON TABLE our_tables TO public;
Then run:
SELECT tablename, description FROM our_tables WHERE schemaname = 'public'
The view is a modified version of the pg_tables view which adds in the description column.
You could also monkey around with the view definition to make it a single query.
I accessed table comments like this:
select c.relname table_name, pg_catalog.obj_description(c.oid) as comment from pg_catalog.pg_class c where c.relname = 'table_name';
and column comments thusly:
SELECT c.column_name, pgd.description FROM pg_catalog.pg_statio_all_tables as st inner join pg_catalog.pg_description pgd on (pgd.objoid=st.relid) inner join information_schema.columns c on (pgd.objsubid=c.ordinal_position and c.table_schema=st.schemaname and c.table_name=st.relname and c.table_name = 'table_name' and c.table_schema = 'public');
I asked a similar question about Postgresql comments last month. If you dig through that, you'll come across some Perl code over on my blog that automates the process of extracting a comment.
To pull out the column names of a table, you can use something like the following:
select
a.attname as "colname"
,a.attrelid as "tableoid"
,a.attnum as "columnoid"
from
pg_catalog.pg_attribute a
inner join pg_catalog.pg_class c on a.attrelid = c.oid
where
c.relname = 'mytable' -- better to use a placeholder
and a.attnum > 0
and a.attisdropped is false
and pg_catalog.pg_table_is_visible(c.oid)
order by a.attnum
You can then use the tableoid,columnoid tuple to extract the comment of each column (see my question).
I just found this here. It will provide you with all kind of metadata on one specific table (type, default value, not null flag, length, comment, foreign key name, primary key name). It seems to work well.
SELECT pg_tables.tablename, pg_attribute.attname AS field,
format_type(pg_attribute.atttypid, NULL) AS "type",
pg_attribute.atttypmod AS len,
(SELECT col_description(pg_attribute.attrelid,
pg_attribute.attnum)) AS comment,
CASE pg_attribute.attnotnull
WHEN false THEN 1 ELSE 0
END AS "notnull",
pg_constraint.conname AS "key", pc2.conname AS ckey,
(SELECT pg_attrdef.adsrc FROM pg_attrdef
WHERE pg_attrdef.adrelid = pg_class.oid
AND pg_attrdef.adnum = pg_attribute.attnum) AS def
FROM pg_tables, pg_class
JOIN pg_attribute ON pg_class.oid = pg_attribute.attrelid
AND pg_attribute.attnum > 0
LEFT JOIN pg_constraint ON pg_constraint.contype = 'p'::"char"
AND pg_constraint.conrelid = pg_class.oid AND
(pg_attribute.attnum = ANY (pg_constraint.conkey))
LEFT JOIN pg_constraint AS pc2 ON pc2.contype = 'f'::"char"
AND pc2.conrelid = pg_class.oid
AND (pg_attribute.attnum = ANY (pc2.conkey))
WHERE pg_class.relname = pg_tables.tablename
-- AND pg_tables.tableowner = "current_user"()
AND pg_attribute.atttypid <> 0::oid
AND tablename='your_table'
ORDER BY field ASC
Source: http://golden13.blogspot.de/2012/08/how-to-get-some-information-about_7.html
Ok, so i worked it out to degree...
select col_description(table id, column number)...
ie: select col_description(36698,2);
That worked, but is there an easier way to do this maybe bringing all the comments on all the columns and using the table name instead of the oid???
To display comments from all columns of all table :
SELECT
cols.table_name,
cols.column_name, (
SELECT
pg_catalog.col_description(c.oid, cols.ordinal_position::int)
FROM
pg_catalog.pg_class c
WHERE
c.oid = (SELECT ('"' || cols.table_name || '"')::regclass::oid)
AND c.relname = cols.table_name
) AS column_comment
FROM
information_schema.columns cols
WHERE
cols.table_name IN (SELECT cols.table_name FROM information_schema.columns)
AND cols.table_catalog = 'your_database_name'
AND cols.table_schema = 'your_schema_name';
You need to execute this query outside any schema/catalog/db
This query is based on another answer in this question which display comments from one table only
To extend on the response provided by #amxy; I found that adding a schema filter can help in some environments. As I found #amxy's solution didn't work until I added by schema filters
SELECT
pg_tables.schemaname,
pg_tables.TABLENAME,
pg_attribute.attname AS field,
format_type(pg_attribute.atttypid, NULL) AS "type",
pg_attribute.atttypmod AS len,
(
SELECT col_description(pg_attribute.attrelid, pg_attribute.attnum)) AS COMMENT,
CASE pg_attribute.attnotnull
WHEN FALSE THEN 1
ELSE 0
END AS "notnull",
pg_constraint.conname AS "key", pc2.conname AS ckey,
(
SELECT pg_attrdef.adsrc
FROM pg_attrdef
WHERE pg_attrdef.adrelid = pg_class.oid
AND pg_attrdef.adnum = pg_attribute.attnum) AS def
FROM pg_tables, pg_class
JOIN pg_attribute
ON pg_class.oid = pg_attribute.attrelid
AND pg_attribute.attnum > 0
LEFT JOIN pg_constraint
ON pg_constraint.contype = 'p'::"char"
AND pg_constraint.conrelid = pg_class.oid
AND
(pg_attribute.attnum = ANY (pg_constraint.conkey))
LEFT JOIN pg_constraint AS pc2
ON pc2.contype = 'f'::"char"
AND pc2.conrelid = pg_class.oid
AND (pg_attribute.attnum = ANY (pc2.conkey))
WHERE pg_class.relname = pg_tables.TABLENAME
AND pg_tables.schemaname IN ('op', 'im', 'cs','usr','li')
-- AND pg_tables.tableowner = "current_user"()
AND pg_attribute.atttypid <> 0::oid
---AND TABLENAME='your_table'
ORDER BY pg_tables.schemaname,
pg_tables.TABLENAME ASC;
RESULTS:
SELECT
relname table_name,
obj_description(oid) table_description,
column_name,
pgd.description column_description
FROM pg_class
INNER JOIN
information_schema.columns
ON table_name = pg_class.relname
LEFT JOIN
pg_catalog.pg_description pgd
ON pgd.objsubid = ordinal_position
WHERE
relname = 'your_table_name'
SELECT sc.table_schema , sc.table_name, sc.column_name, col_description(pc."oid" , sc.ordinal_position) col_description FROM pg_class pc
INNER JOIN pg_namespace ns ON ns."oid" =pc.relnamespace
INNER JOIN information_schema.COLUMNS sc ON sc.table_name=pc.relname AND sc.table_schema=ns.nspname
WHERE 1=1
AND upper(ns.nspname) = 'TABLE_SCHEMA'
AND upper(pc.relname) = 'TABLE_NAME'
Retrieving Comments from a PostgreSQL DB
I need to query Redshift metadata to get a list of table columns that includes information whether the column is part of primary key or not.
There is a post already List columns with indexes in PostgreSQL that has an answer for PostgreSQL, however unfortunately, it fails on Redshift with "ERROR: 42809: op ANY/ALL (array) requires array on right side"
I figured out how to do it with the help of this https://bitbucket.org/zzzeek/sqlalchemy/pull-request/6/sqlalchemy-to-support-postgresql-80/diff
SELECT attname column_name, attnotnull,
format_type(atttypid, atttypmod) as column_type, atttypmod,
i.indisprimary as primary_key,
col_description(attrelid, attnum) as description
FROM pg_attribute c
LEFT OUTER JOIN pg_index i
ON c.attrelid = i.indrelid AND i.indisprimary AND
c.attnum = ANY(string_to_array(textin(int2vectorout(i.indkey)), ' '))
where c.attnum > 0 AND NOT c.attisdropped AND c.attrelid = :tableOid
order by attnum
The following worked for me:
SELECT n.nspname as schema_name,
t.relname as table_name,
i.relname as index_name,
c.contype as index_type,
a.attname as column_name,
a.attnum AS column_position
FROM pg_class t
INNER JOIN pg_index AS ix ON t.oid = ix.indrelid
INNER JOIN pg_constraint AS c ON ix.indrelid = c.conrelid
INNER JOIN pg_class AS i ON i.oid = ix.indexrelid
INNER JOIN pg_attribute AS a ON a.attrelid = t.oid
AND a.attnum= ANY(string_to_array(textin(int2vectorout(ix.indkey)),' ')::int[])
INNER JOIN pg_namespace AS n ON n.oid = t.relnamespace;
You can leverage the table DDL view AWS published a few months ago (https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql) by picking out the constraint component and parsing out the key columns:
select schemaname,tablename, substring(ddl,charindex('(',ddl)+1, charindex(')',ddl)-1-charindex('(',ddl))
from
(
SELECT
n.nspname AS schemaname
,c.relname AS tablename
,200000000 + CAST(con.oid AS INT) AS seq
,'\t,' + pg_get_constraintdef(con.oid) AS ddl
FROM
pg_constraint AS con
INNER JOIN pg_class AS c
ON c.relnamespace = con.connamespace
AND c.relfilenode = con.conrelid
INNER JOIN pg_namespace AS n
ON n.oid = c.relnamespace
WHERE c.relkind = 'r'
ORDER BY seq
)
Note that this query also gives you foreign key columns. It's easy enough to filter those out by appending the query with
where ddl like '%PRIMARY KEY%'
Use below query:
select * from pg_table_def where tablename = 'mytablename'
This will give you all columns for table along with their data type , encoding and if it has sort key or dist key.
I am using the following query to discover (1) the primary key columns and (2) if the columns have a default value from the information_schema in Postgresql 9.1.
SELECT kcu.column_name, (c.column_default is not null) AS has_default
FROM information_schema.key_column_usage kcu
JOIN information_schema.table_constraints tc ON tc.constraint_name = kcu.constraint_name
JOIN information_schema.columns c on c.column_name = kcu.column_name and c.table_name = kcu.table_name
WHERE tc.constraint_type = 'PRIMARY KEY' AND kcu.table_name like :tablename
It works fine when run as the database owner, but when I run it as a "read-only" user (which I need to do in my application), it returns no data. Some research revealed that the problem is the information.table_constraints view; from the documentation:
The view table_constraints contains all constraints belonging to tables that the current user owns or has some non-SELECT privilege on.
So in order to retrieve table_constraints, my login role needs more than SELECT on the table? Is there no way to get the information from information_schema without giving write permissions to the login role?
Use pg_* views instead of information_schema views. pg_* views display all information regardles of granted privileges.
Try this query:
select
t.relname as table_name,
i.relname as index_name,
a.attname as column_name,
d.adsrc as default_value
from
pg_class t
join pg_attribute a on a.attrelid = t.oid
join pg_index ix on t.oid = ix.indrelid AND a.attnum = ANY(ix.indkey)
join pg_class i on i.oid = ix.indexrelid
left join pg_attrdef d on d.adrelid = t.oid and d.adnum = a.attnum
where
t.relkind = 'r'
and t.relname in ( 'aa', 'bb', 'cc' )
order by
t.relname,
i.relname,
a.attnum;
An example of the query results:
create table aa(
x int primary KEY
);
create table bb(
x int default 1,
constraint pk primary key ( x )
);
create table cc(
x int default 20,
y varchar(10) default 'something',
constraint cc_pk primary key ( x, y )
);
table_name | index_name | column_name | default_value
------------+------------+-------------+--------------------------------
aa | aa_pkey | x |
bb | pk | x | 1
cc | cc_pk | x | 20
cc | cc_pk | y | 'something'::character varying
This is correct, the official postgresql query is below
http://wiki.postgresql.org/wiki/Retrieve_primary_key_columns
if schema is needed the query is as follows
SELECT
pg_attribute.attname,
format_type(pg_attribute.atttypid, pg_attribute.atttypmod)
FROM pg_index, pg_class, pg_attribute, pg_namespace
WHERE
pg_class.oid = 'MY TABLE'::regclass AND
indrelid = pg_class.oid AND
nspname = 'MY CLASS' AND
pg_class.relnamespace = pg_namespace.oid AND
pg_attribute.attrelid = pg_class.oid AND
pg_attribute.attnum = any(pg_index.indkey)
AND indisprimary
The difference can be up to 6000~7000 times. The pg_ one runs often in 0.56ms where the schema based one can run up 6500ms. This is a huge difference especially if you have a high load on the server.
There is another way to provide access for data in information_schema.
A. Envelop SQL in a function with SECURITY DEFINER modifier
CREATE FUNCTION fn_inf(name)
RETURNS TABLE (column_name information_schema.sql_identifier, has_default bool)
LANGUAGE SQL
SECURITY DEFINER
AS $$
SELECT kcu.column_name, (c.column_default is not null) AS has_default
FROM information_schema.key_column_usage kcu
JOIN information_schema.table_constraints tc ON tc.constraint_name = kcu.constraint_name
JOIN information_schema.columns c on c.column_name = kcu.column_name and c.table_name = kcu.table_name
WHERE tc.constraint_type = 'PRIMARY KEY' AND kcu.table_name like $1;
$$;
B. GRANT EXECUTE to user read_only
GRANT EXECUTE ON FUNCTION fn_inf to read_only;
C. Use as user read_only
SELECT * FROM fn_inf('spatial_ref_sys');
column_name
has_default
srid
false