I want to decrease local test execution time by making all tables UNLOGGED
. I want to write sql script, which will run after all conversion and make them UNLOGGED
. But I found problem - tables relate each other with FK
, so postgresql prohibit make table UNLOGGED
(through ALTER
) if it related from other table which is not UNLOGGED
yet.
Is there better way then list all ALTER
in correct order - I have more then 150 tables? For example, apply it on database level.
You have to ALTER them in right order I'm afraid. You can select https://www.postgresql.org/docs/current/static/catalog-pg-constraint.html and loop for referencing tables first and then alter the rest:
begin;
do
$$
declare
_r record;
_t text;
begin
for _r in (
select relname,conrelid
from pg_constraint
join pg_class c on c.oid = conrelid
where confkey is not null
order by conrelid desc
-- Order by oid with logic that you should start from latest added objects to earliest - of course it does not garantee anything
) loop
_t := format('alter table %I set unlogged',_r.relname);
raise info '%',_t;
execute _t;
end loop;
for _r in (select tablename from pg_tables where tablename like 's%' and schemaname = 'public') loop
_t := format('alter table %I set unlogged',_r.tablename);
raise info '%',_t;
execute _t;
end loop;
end;
$$
;
rollback;
By all means it will fail if you have recursive FK:
t=# create table s134(i int primary key, e int);
CREATE TABLE
t=# create table s135(i int references s134(i), e int primary key);
CREATE TABLE
t=# alter table s134 add constraint c1 foreign key (e) references s135(e);
ALTER TABLE
t=# alter table s134 set unlogged;
ERROR: could not change table "s134" to unlogged because it references logged table "s135"
t=# alter table s135 set unlogged;
ERROR: could not change table "s135" to unlogged because it references logged table "s134"
But you would not achieve that any way I believe.
Also don't forget that after unclean shutdown or failure unlogged tables will be truncated.
And lastly you say "after all conversion" - if you create, convert etc, maybe you should just create them unlogged?..
I would drop and re-create all foreign keys. You can automate this.
The following query will generate the necessary DDL statements for all foreign keys. You need to save the output of that into a file, which you can later use to restore all foreign keys.
select format('alter table %I.%I add constraint %I ', ns.nspname, tb.relname, conname)||
pg_get_constraintdef(c.oid, true)||';' as ddl
from pg_constraint c
join pg_class tb on tb.oid = c.conrelid
join pg_namespace ns on ns.oid = tb.relnamespace
where ns.nspname not in ('pg_catalog', 'information_schema')
and ns.nspname not like 'pg_temp%'
and c.contype in ('f')
Then generate a script to drop all constraints:
select format('alter table %I.%I drop constraint %I cascade;', ns.nspname, tb.relname, c.conname) as ddl
from pg_constraint c
join pg_class tb on tb.oid = c.conrelid
join pg_namespace ns on ns.oid = tb.relnamespace
where ns.nspname not in ('pg_catalog', 'information_schema')
and ns.nspname not like 'pg_temp%'
and c.contype in ('f');
Of course you have to run the query to generate the FKs before you drop them ;)
I had difficulties with the accepted answer, because it relies on a heuristic (which may not apply) to get the ordering correct. I have reworked the suggested answer using a (somewhat verbose) recursive query which allows one to get an exact ordering required. I have not tested it with recursive FKs, I suspect that the recursive query will not terminate. Note that I have restricted the query to apply to tables in the public
schema, modify to suit your own needs.
Unlog all tables:
do
$$
declare
_r record;
_t text;
begin
for _r in (
WITH RECURSIVE constraints AS (
SELECT
tc.table_schema
, tc.table_name
, kcu.column_name
, ccu.table_name AS foreign_table_name
FROM
information_schema.table_constraints AS tc
LEFT OUTER JOIN information_schema.key_column_usage AS kcu
ON tc.constraint_name = kcu.constraint_name
AND tc.table_schema = kcu.table_schema
LEFT OUTER JOIN information_schema.constraint_column_usage AS ccu
ON ccu.constraint_name = tc.constraint_name
AND ccu.table_schema = tc.table_schema
WHERE (tc.constraint_type IS NULL OR tc.constraint_type = 'FOREIGN KEY'))
, tables_and_constraints AS (
SELECT
t.table_schema
, t.table_name
, c.foreign_table_name
FROM information_schema.tables AS t
LEFT JOIN constraints AS c USING (table_name)
WHERE t.table_type <> 'VIEW')
, dependent_table_constraints AS (
SELECT tc.table_schema
, tc.table_name
, tc.foreign_table_name
, 0 AS depth
FROM tables_and_constraints AS tc
WHERE foreign_table_name IS NULL
UNION
SELECT tc.table_schema
, tc.table_name
, tc.foreign_table_name
, dtc.depth + 1
FROM tables_and_constraints AS tc
INNER JOIN dependent_table_constraints AS dtc ON tc.foreign_table_name = dtc.table_name
) SELECT table_name, max(depth) as depth FROM dependent_table_constraints
WHERE table_schema = 'public'
GROUP BY table_name
ORDER BY depth DESC
) loop
_t := format('ALTER TABLE %I SET UNLOGGED',_r.table_name);
raise info '%',_t;
execute _t;
end loop;
end;
$$
;
Relog all tables:
do
$$
declare
_r record;
_t text;
begin
for _r in (
WITH RECURSIVE constraints AS (
SELECT
tc.table_schema
, tc.table_name
, kcu.column_name
, ccu.table_name AS foreign_table_name
FROM
information_schema.table_constraints AS tc
LEFT OUTER JOIN information_schema.key_column_usage AS kcu
ON tc.constraint_name = kcu.constraint_name
AND tc.table_schema = kcu.table_schema
LEFT OUTER JOIN information_schema.constraint_column_usage AS ccu
ON ccu.constraint_name = tc.constraint_name
AND ccu.table_schema = tc.table_schema
WHERE (tc.constraint_type IS NULL OR tc.constraint_type = 'FOREIGN KEY'))
, tables_and_constraints AS (
SELECT
t.table_schema
, t.table_name
, c.foreign_table_name
FROM information_schema.tables AS t
LEFT JOIN constraints AS c USING (table_name)
WHERE t.table_type <> 'VIEW')
, dependent_table_constraints AS (
SELECT tc.table_schema
, tc.table_name
, tc.foreign_table_name
, 0 AS depth
FROM tables_and_constraints AS tc
WHERE foreign_table_name IS NULL
UNION
SELECT tc.table_schema
, tc.table_name
, tc.foreign_table_name
, dtc.depth + 1
FROM tables_and_constraints AS tc
INNER JOIN dependent_table_constraints AS dtc ON tc.foreign_table_name = dtc.table_name
) SELECT table_name, max(depth) as depth FROM dependent_table_constraints
WHERE table_schema = 'public'
GROUP BY table_name
ORDER BY depth ASC
) loop
_t := format('ALTER TABLE %I SET LOGGED',_r.table_name);
raise info '%',_t;
execute _t;
end loop;
end;
$$
;
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