Related
I am looking for a pgsql query to pull the last PK for all tables given the db schema.
Need this for my db migration work.
You can do this with a variation of a dynamic row count query:
with pk_list as (
select tbl_ns.nspname as table_schema,
tbl.relname as table_name,
cons.conname as pk_name,
col.attname as pk_column
from pg_class tbl
join pg_constraint cons on tbl.oid = cons.conrelid and cons.contype = 'p'
join pg_namespace tbl_ns on tbl_ns.oid = tbl.relnamespace
join pg_attribute col on col.attrelid = tbl.oid and col.attnum = cons.conkey[1]
join pg_type typ on typ.oid = col.atttypid
where tbl.relkind = 'r'
and cardinality(cons.conkey) = 1 -- only single column primary keys
and tbl_ns.nspname not in ('pg_catalog', 'information_schema')
and typ.typname in ('int2','int4','int8','varchar','numeric','float4','float8','date','timestamp','timestamptz')
and has_table_privilege(format('%I.%I', tbl_ns.nspname, tbl.relname), 'select')
), maxvals as (
select table_schema, table_name, pk_column,
(xpath('/row/max/text()',
query_to_xml(format('select max(%I) from %I.%I', pk_column, table_schema, table_name), true, true, ''))
)[1]::text as max_val
from pk_list
)
select table_schema,
table_name,
pk_column,
max_val
from maxvals;
The first CTE (pk_list ) retrieves the name of the primary key column for each "user" table (that is: tables that are not system tables)
The second CTE (maxvals) then creates a select statement that retrieves the max value for each PK column from the first CTE and runs that query using query_to_xml(). The xpath() function is then used to parse the XML and return the max value as a text value (so it's possible to mix numbers and varchars)
The final select then simply displays the result from that.
The above has the following restrictions:
Only single-column primary keys are considered
It only deals with data types that support using max() on them (e.g. UUID columns are not included)
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
Hello I am trying to retrieve the schema of an existing table. I am mysql developer and am trying to work with amazon redshift. How can I export the schema of an existing table. In mysql we can use the show create table command.
SHOW CREATE TABLE tblName;
Recently I wrote a python script to clone table schemas between redshift clusters. If you only want the columns and column types of a table, you can do it via:
select column_name,
case
when data_type = 'integer' then 'integer'
when data_type = 'bigint' then 'bigint'
when data_type = 'smallint' then 'smallint'
when data_type = 'text' then 'text'
when data_type = 'date' then 'date'
when data_type = 'real' then 'real'
when data_type = 'boolean' then 'boolean'
when data_type = 'double precision' then 'float8'
when data_type = 'timestamp without time zone' then 'timestamp'
when data_type = 'character' then 'char('||character_maximum_length||')'
when data_type = 'character varying' then 'varchar('||character_maximum_length||')'
when data_type = 'numeric' then 'numeric('||numeric_precision||','||numeric_scale||')'
else 'unknown'
end as data_type,
is_nullable,
column_default
from information_schema.columns
where table_schema = 'xxx' and table_name = 'xxx' order by ordinal_position
;
But if you need the compression types and distkey/sortkeys, you need to query another table:
select * from pg_table_def where tablename = 'xxx' and schemaname='xxx';
This query will give you the complete schema definition including the Redshift specific attributes distribution type/key, sort key, primary key, and column encodings in the form of a create statement as well as providing an alter table statement that sets the owner to the current owner. The only thing it can't tell you are foreign keys. I'm working on the latter, but there's a current privilege issue in RS that prevents us from querying the right tables. This query could use some tuning, but I haven't had time or the need to work it further.
select pk.pkey, tm.schemaname||'.'||tm.tablename, 'create table '||tm.schemaname||'.'||tm.tablename
||' ('
||cp.coldef
-- primary key
||decode(pk.pkey,null,'',pk.pkey)
-- diststyle and dist key
||decode(d.distkey,null,') diststyle '||dist_style||' ',d.distkey)
--sort key
|| (select decode(skey,null,'',skey) from (select
' sortkey(' ||substr(array_to_string(
array( select ','||cast(column_name as varchar(100)) as str from
(select column_name from information_schema.columns col where col.table_schema= tm.schemaname and col.table_name=tm.tablename) c2
join
(-- gives sort cols
select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute pa where
pa.attnum > 0 AND NOT pa.attisdropped AND pa.attsortkeyord > 0
) st on tm.tableid=st.tableid and c2.column_name=st.colname order by sort_col_order
)
,'')
,2,10000) || ')' as skey
))
||';'
-- additional alter table queries here to set owner
|| 'alter table '||tm.schemaname||'.'||tm.tablename||' owner to "'||tm.owner||'";'
from
-- t master table list
(
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid ,use2.usename as owner, decode(c.reldiststyle,0,'EVEN',1,'KEY',8,'ALL') as dist_style
FROM pg_namespace n, pg_class c, pg_user use2
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
AND c.relname <> 'temp_staging_tables_1'
and c.relowner = use2.usesysid
) tm
-- cp creates the col params for the create string
join
(select
substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)) as tableid
,substr(replace(replace(str,'ZZZ',''),'QQQ'||substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)),''),2,10000) as coldef
from
( select array_to_string(array(
SELECT 'QQQ'||cast(t.tableid as varchar(10))||'ZZZ'|| ','||column_name||' '|| decode(udt_name,'bpchar','char',udt_name) || decode(character_maximum_length,null,'', '('||cast(character_maximum_length as varchar(9))||')' )
-- default
|| decode(substr(column_default,2,8),'identity','',null,'',' default '||column_default||' ')
-- nullable
|| decode(is_nullable,'YES',' NULL ','NO',' NOT NULL ')
-- identity
|| decode(substr(column_default,2,8),'identity',' identity('||substr(column_default,(charindex('''',column_default)+1), (length(column_default)-charindex('''',reverse(column_default))-charindex('''',column_default) ) ) ||') ', '')
-- encoding
|| decode(enc,'none','',' encode '||enc)
as str
from
-- ci all the col info
(
select cast(t.tableid as int), cast(table_schema as varchar(100)), cast(table_name as varchar(100)), cast(column_name as varchar(100)),
cast(ordinal_position as int), cast(column_default as varchar(100)), cast(is_nullable as varchar(20)) , cast(udt_name as varchar(50)) ,cast(character_maximum_length as int),
sort_col_order , decode(d.colname,null,0,1) dist_key , e.enc
from
(select * from information_schema.columns c where c.table_schema= t.schemaname and c.table_name=t.tablename) c
left join
(-- gives sort cols
select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attsortkeyord > 0
) s on t.tableid=s.tableid and c.column_name=s.colname
left join
(-- gives encoding
select attrelid as tableid, attname as colname, format_encoding(a.attencodingtype::integer) AS enc from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped
) e on t.tableid=e.tableid and c.column_name=e.colname
left join
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname
order by ordinal_position
) ci
-- for the working array funct
), '') as str
from
(-- need tableid
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid
FROM pg_namespace n, pg_class c
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
) t
)) cp on tm.tableid=cp.tableid
-- primary key query here
left join
(select c.oid as tableid, ', primary key '|| substring(pg_get_indexdef(indexrelid),charindex('(',pg_get_indexdef(indexrelid))-1 ,60) as pkey
from pg_index i , pg_namespace n, pg_class c
where i.indisprimary=true
and i.indrelid =c.oid
and n.oid = c.relnamespace
) pk on tm.tableid=pk.tableid
-- dist key
left join
( select
-- close off the col defs after the primary key
')' ||
' distkey('|| cast(column_name as varchar(100)) ||')' as distkey, t.tableid
from information_schema.columns c
join
(-- need tableid
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid
FROM pg_namespace n, pg_class c
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
) t on c.table_schema= t.schemaname and c.table_name=t.tablename
join
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname
) d on tm.tableid=d.tableid
where tm.schemaname||'.'||tm.tablename='myschema.mytable'
If you want to get the table structure with create statement, constraints and triggers, you can use pg_dump utility
pg_dump -U user_name -s -t table_name -d db_name
Note: -s used for schema only dump
if you want to take the data only dump , you can use -a switch.
This will output the create syntax with all the constraints. Hope this will help you.
I did not find any complete solutions out there.
And wrote a python script:
https://github.com/cxmcc/redshift_show_create_table
It will work like pg_dump, plus dealing with basic redshift features, SORTKEY/DISTKEY/DISTSTYLES etc.
As show table doesn't work on Redshift:
show table <YOUR_TABLE>;
ERROR: syntax error at or near "<YOUR_TABLE>"
We can use pg_table_def table to get the schema out:
select "column", type, encoding, distkey, sortkey, "notnull"
from pg_table_def
where tablename = '<YOUR_TABLE>';
NOTE: If the schema is not on the search path, add it to search path using:
set search_path to '$user', 'public', '<YOUR_SCHEMA>';
For redshift please try
show table <**tablename**> ;
In Postgres, you'd query the catalog.
From with psql use the shorthands to a variety of commands whose list you'll get by using \? (for help). Therefor, either of:
\d yourtable
\d+ yourtable
For use in an app, you'll need to learn the relevant queries involved. It's relatively straightforward by running psql -E (for echo hidden queries) instead of plain psql.
If you need the precise create table statement, see #Anant answer.
One easy way to do this is to use the utility provided by AWS. All you need to do is to create the view in your database and then query that view to get any table ddl. The advantage to use this view is that it will give you the sortkey and distkey as well which was used in original create table command.
https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql
Once the view is created, to get the the ddl of any table. You need to query like this -
select ddl from table where tablename='table_name' and schemaname='schemaname';
Note: Admin schema might not be already there in your cluster. So you can create this view in public schema.
Below query will generate the DDL of the table for you:
SELECT ddl
FROM admin.v_generate_tbl_ddl
WHERE schemaname = '<schemaname>'
AND tablename in (
'<tablename>');
Are you needing to retrieve it programatically or from the psql prompt?
In psql use : \d+ tablename
Programatically, you can query the ANSI standard INFORMATION_SCHEMA views documented here:
http://www.postgresql.org/docs/9.1/static/information-schema.html
The INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.COLUMNS views should have what you need.
You can use admin view provided by AWS Redshift - https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql
once you have created the view you can get schema creation script by running:
select * from <db_schema>.v_generate_tbl_ddl where tablename = '<table_name>'
To get the column data and schema of a particular table:
select * from information_schema.columns where tablename='<<table_name>>'
To get the information of a table metadata fire the below query
select * from information_schema.tables where schema='<<schema_name>>'
In the new "query editor 2", you can right click on a table and select "show definition", this will place the DDL for the table in a query window.
The below command will work:
mysql > show create table test.users_info;
Redshift/postgress >pg_dump -U root-w --no-password -h 62.36.11.547 -p 5439 -s -t test.users_info ;
I have two tables (tbl and tbl_new) that both use the same sequence (tbl_id_seq). I'd like to drop one of those tables. On tbl, I've removed the modifier "not null default nextval('tbl_id_seq'::regclass)" but that modifier remains on tbl_new. I'm getting the following error:
ERROR: cannot drop table tbl because other objects depend on it
DETAIL: default for table tbl_new column id depends on sequence tbl_id_seq
After reviewing http://www.postgresql.org/docs/9.1/static/sql-droptable.html
It looks like there is only CASCADE and RESTRICT as options.
You need to decouple the sequence and the table it "belongs" to:
ALTER SEQUENCE "tbl_id_seq" OWNED BY NONE;
I suppose it was created automatically (and "bound") by defining the tbl_id field of tbl as SERIAL.
To find sequences and all tables that depend on them via column default:
SELECT sn.nspname || '.' || s.relname AS seq
,tn.nspname || '.' || t.relname AS tbl
FROM pg_class s
JOIN pg_namespace sn ON sn.oid = s.relnamespace
LEFT JOIN pg_depend d ON d.refobjid = s.oid AND d.deptype <> 'i'
LEFT JOIN pg_attrdef ad ON ad.oid = d.objid
LEFT JOIN pg_class t ON t.oid = ad.adrelid
LEFT JOIN pg_namespace tn ON tn.oid = t.relnamespace
WHERE s.relkind = 'S'
AND s.relname ~~ '%part_of_seq_name%' -- enter search term here
ORDER BY 1,2;
Now with LEFT JOIN to show "free-standing" sequences as well.
You can then use the method #Milen posted to make the sequence "free-standing".
I posted a related answer a few days ago.
I can run the following line:
ALTER SEQUENCE seqName OWNED BY table.id;
How can I get the 'owner' set by OWNED BY for a sequence (in this case: table.id)?
You may use following query:
select s.relname as seq, n.nspname as sch, t.relname as tab, a.attname as col
from pg_class s
join pg_depend d on d.objid=s.oid and d.classid='pg_class'::regclass and d.refclassid='pg_class'::regclass
join pg_class t on t.oid=d.refobjid
join pg_namespace n on n.oid=t.relnamespace
join pg_attribute a on a.attrelid=t.oid and a.attnum=d.refobjsubid
where s.relkind='S' and d.deptype='a'
It returns all sequences with owner information. Just filter them in WHERE clause and that's it.
Get the "owning" table and column
ALTER SEQUENCE seqName OWNED BY table.id;
Your ALTER SEQUENCE statement causes an entry in the system catalog pg_depend with the dependency type (deptype) 'a' and a refobjsubid greater than 0, pointing to the attribute number (attnum) in pg_attribute. With that knowledge you can devise a simple query:
SELECT d.refobjid::regclass, a.attname
FROM pg_depend d
JOIN pg_attribute a ON a.attrelid = d.refobjid
AND a.attnum = d.refobjsubid
WHERE d.objid = 'public."seqName"'::regclass -- your sequence here
AND d.refobjsubid > 0
AND d.classid = 'pg_class'::regclass;
Double quotes ("") are only needed for otherwise illegal names (mixed case, reserved words, ...).
No need to assert that refclassid is of type regclass since the join to pg_attribute does that automatically.
No need to assert that the sequence is a sequence since schema-qualified object names are unique across the database.
No need to join to pg_class or pg_namespace at all.
The schema name is only needed to disambiguate or if it's not in the search_path.
The same table name (or sequence name for that matter) can be used in multiple schemas. A cast to the object identifier type regclass observes the current search_path to pick the best match if you omit the schema qualification. If the table is not visible, you get an error message.
What's more, a regclass type is displayed as text to the user automatically. (If not, cast to text.) The schema-name is prepended automatically where necessary to be unambiguous in your session.
Get the actual "owner" (the role)
To get the role owning a specific sequence, as requested:
SELECT c.relname, u.usename
FROM pg_class c
JOIN pg_user u ON u.usesysid = c.relowner
WHERE c.oid = '"seqName"'::regclass; -- your sequence here
I was able to list the table and corresponding sequence for a particular column using the following SQL statement:
SELECT table_schema
, table_name
, column_name
, LTRIM(RTRIM(RTRIM(column_default, '::regclass)'),''''),'nextval(''') AS SEQUENCE_NAME
FROM information_schema.columns
WHERE column_default like '%nextval%';
SELECT c.relname,u.usename
FROM pg_class c, pg_user u
WHERE c.relowner = u.usesysid and c.relkind = 'S'
AND relnamespace IN (
SELECT oid
FROM pg_namespace
WHERE nspname NOT LIKE 'pg_%'
AND nspname != 'information_schema'
);
I use that query for get all queries.
Change CTE to filter the result
WITH table_with_sequence as (
SELECT
d.refobjid::regclass::text tablename,
c.relname::text sequencename,
np.nspname::text schemaname,
a.attname::text attname,
u.usename::text
FROM
pg_depend d
INNER JOIN pg_class c ON c.oid = d.objid
AND c.relkind = 'S'
INNER JOIN pg_namespace np ON np.oid = c.relnamespace
AND (np.nspname NOT LIKE 'pg_%'
AND np.nspname != 'information_schema')
INNER JOIN pg_user u ON u.usesysid = c.relowner
INNER JOIN pg_attribute a ON a.attrelid = d.refobjid
AND a.attnum = d.refobjsubid
)
SELECT
'ALTER SEQUENCE '|| QUOTE_LITERAL(QUOTE_IDENT(schemaname) || '.' || QUOTE_IDENT(sequencename)) ||' OWNED BY ' || tablename || '.' || QUOTE_IDENT(attname)
FROM table_with_sequence