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Merged
olirice merged 1 commit into from
Feb 13, 2024
Merged

Test the foreign key index coverage lint #1

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101 changes: 49 additions & 52 deletions lints/0001_unindexed_foreign_keys.sql
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Original file line number Diff line number Diff line change
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create view "0001_unindexed_foreign_keys" as

with foreign_keys as (
select
cl.oid::regclass as table_,
ct.conname as fkey_name,
ct.conkey col_attnums
from
pg_constraint ct
join pg_class cl -- fkey owning table
on ct.conrelid = cl.oid
left join pg_depend d
on d.objid = cl.oid
and d.deptype = 'e'
where
ct.contype = 'f' -- foreign key constraints
and d.objid is null -- exclude tables that are dependencies of extensions
and cl.relnamespace::regnamespace::text not in (
'pg_catalog', 'information_schema', 'auth', 'storage', 'vault', 'extensions'
)
),
index_ as (
select
indrelid::regclass as table_,
indexrelid::regclass as index_,
string_to_array(indkey::text, ' ')::smallint[] as col_attnums
from
pg_index
where
indisvalid
)
select
'unindexed_foreign_key' as name,
'WARN' as level,
'INTERNAL' as facing,
'Foreign keys without indexes can degrade performance on joins.' as description,
'0001_unindexed_foreign_keys' as name,
'INFO' as level,
'EXTERNAL' as facing,
'Identifies foreign key constraints without a covering index, which can impact database performance.' as description,
format(
'The foreign key on table %I.%I involving columns (%s) is not indexed.',
ns.nspname,
cl.relname,
string_agg(a.attname, ', ' order by a.attnum)
) as detail,
format(
'create index on %I.%I(%s);',
ns.nspname,
cl.relname,
string_agg(a.attname, ', ' order by a.attnum)
) as remediation,
'{}'::jsonb as metadata,
format(
'unindexed_foreign_key_%s_%s_%s',
ns.nspname,
cl.relname,
string_agg(a.attname, '_' order by a.attnum)
) as cache_key
'Table "%s" has a foreign key "%s" without a covering index. This can lead to suboptimal query performance.',
fk.table_, fk.fkey_name
) as detail,
null as remediation,
jsonb_build_object(
'table', fk.table_,
'fkey_name', fk.fkey_name,
'fkey_columns', fk.col_attnums
) as metadata,
format('0001_unindexed_foreign_keys_%s_%s', fk.table_, fk.fkey_name) as cache_key
from
pg_constraint ct
join pg_class cl
on ct.conrelid = cl.oid
join pg_namespace ns
on cl.relnamespace = ns.oid
join pg_attribute a
on a.attrelid = cl.oid
and a.attnum = any(ct.conkey)
left join pg_index ix
on ix.indrelid = ct.conrelid
left join lateral (
select array_agg(i) as indkeys
from unnest(ix.indkey) with ordinality as u(i, ord)
) ix_keys on true
left join pg_depend d
on d.refobjid = cl.oid
and d.deptype = 'e'
left join pg_extension e
on e.oid = d.objid
foreign_keys fk
left join index_ idx on fk.table_ = idx.table_ and fk.col_attnums = idx.col_attnums
where
ct.contype = 'f' -- foreign key constraints
and ns.nspname not in ('pg_catalog', 'information_schema', 'auth', 'storage', 'vault', 'extensions')
and e.oid is null -- exclude tables that are dependencies of extensions
and (ix.indrelid is null or not (ct.conkey <@ ix_keys.indkeys))
group by
ns.nspname,
cl.relname,
ct.oid
having
bool_or(ix.indrelid is null) -- check if there's no index covering all columns of the foreign key;

idx.index_ is null
order by
fk.table_,
fk.fkey_name;
61 changes: 61 additions & 0 deletions test/expected/0001_unindexed_foreign_keys.out
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begin;
savepoint a;
-- Simple Case
-- No index on bbb.aaa_id produces an error
create table aaa(
id int primary key
);
create table bbb(
id int primary key,
aaa_id int references aaa(id) -- no index
);
select * from "0001_unindexed_foreign_keys";
name | level | facing | description | detail | remediation | metadata | cache_key
-----------------------------+-------+----------+-----------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+-------------+-----------------------------------------------------------------------+-------------------------------------------------
0001_unindexed_foreign_keys | INFO | EXTERNAL | Identifies foreign key constraints without a covering index, which can impact database performance. | Table "bbb" has a foreign key "bbb_aaa_id_fkey" without a covering index. This can lead to suboptimal query performance. | | {"table": "bbb", "fkey_name": "bbb_aaa_id_fkey", "fkey_columns": [2]} | 0001_unindexed_foreign_keys_bbb_bbb_aaa_id_fkey
(1 row)

-- When a covering index is created, the error goes away
create index on bbb(aaa_id);
select * from "0001_unindexed_foreign_keys";
name | level | facing | description | detail | remediation | metadata | cache_key
------+-------+--------+-------------+--------+-------------+----------+-----------
(0 rows)

rollback to savepoint a;
-- Multi-column Case
-- No index on bbb(foo, bar)
create table aaa(
foo int,
bar int,
primary key (foo, bar)
);
create table bbb(
id int primary key,
foo int,
bar int,
foreign key (foo, bar) references aaa(foo, bar)
);
select * from "0001_unindexed_foreign_keys";
name | level | facing | description | detail | remediation | metadata | cache_key
-----------------------------+-------+----------+-----------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------+-------------+---------------------------------------------------------------------------+--------------------------------------------------
0001_unindexed_foreign_keys | INFO | EXTERNAL | Identifies foreign key constraints without a covering index, which can impact database performance. | Table "bbb" has a foreign key "bbb_foo_bar_fkey" without a covering index. This can lead to suboptimal query performance. | | {"table": "bbb", "fkey_name": "bbb_foo_bar_fkey", "fkey_columns": [2, 3]} | 0001_unindexed_foreign_keys_bbb_bbb_foo_bar_fkey
(1 row)

-- Confirm that an index on the correct columns but in the wrong order
-- does NOT resolve the issue
create index on bbb(bar, foo);
select * from "0001_unindexed_foreign_keys";
name | level | facing | description | detail | remediation | metadata | cache_key
-----------------------------+-------+----------+-----------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------+-------------+---------------------------------------------------------------------------+--------------------------------------------------
0001_unindexed_foreign_keys | INFO | EXTERNAL | Identifies foreign key constraints without a covering index, which can impact database performance. | Table "bbb" has a foreign key "bbb_foo_bar_fkey" without a covering index. This can lead to suboptimal query performance. | | {"table": "bbb", "fkey_name": "bbb_foo_bar_fkey", "fkey_columns": [2, 3]} | 0001_unindexed_foreign_keys_bbb_bbb_foo_bar_fkey
(1 row)

-- When we create a multi-column index in the correct order the issue is resolved
create index on bbb(foo, bar);
select * from "0001_unindexed_foreign_keys";
name | level | facing | description | detail | remediation | metadata | cache_key
------+-------+--------+-------------+--------+-------------+----------+-----------
(0 rows)

rollback;
55 changes: 55 additions & 0 deletions test/sql/0001_unindexed_foreign_keys.sql
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begin;

savepoint a;

-- Simple Case
-- No index on bbb.aaa_id produces an error
create table aaa(
id int primary key
);

create table bbb(
id int primary key,
aaa_id int references aaa(id) -- no index
);

select * from "0001_unindexed_foreign_keys";


-- When a covering index is created, the error goes away
create index on bbb(aaa_id);
select * from "0001_unindexed_foreign_keys";


rollback to savepoint a;


-- Multi-column Case
-- No index on bbb(foo, bar)
create table aaa(
foo int,
bar int,
primary key (foo, bar)
);

create table bbb(
id int primary key,
foo int,
bar int,
foreign key (foo, bar) references aaa(foo, bar)
);

select * from "0001_unindexed_foreign_keys";

-- Confirm that an index on the correct columns but in the wrong order
-- does NOT resolve the issue

create index on bbb(bar, foo);
select * from "0001_unindexed_foreign_keys";

-- When we create a multi-column index in the correct order the issue is resolved
create index on bbb(foo, bar);
select * from "0001_unindexed_foreign_keys";


rollback;