![]() Stk_order_fulfillment | freighter_id | 0 bytes | stk_order_fulfillment_freighter_id_fkey | stk_freighter Stk_order_line | product_id | 0 bytes | stk_order_line_product_id_fkey | cnt_product Stk_order | freighter_id | 0 bytes | stk_order_freighter_id_fkey | stk_freighter Stk_purchase_line | reference_id | 0 bytes | stk_purchase_line_reference_id_fkey | stk_reference Stk_purchase | supplier_id | 0 bytes | stk_purchase_supplier_id_fkey | stk_supplier Stk_purchase | parent_id | 0 bytes | stk_purchase_parent_id_fkey | stk_purchase Stk_product_part | part_id | 0 bytes | stk_product_part_part_id_fkey | stk_part Stk_warehouse_part_log | src_warehouse_id | 0 bytes | stk_warehouse_part_log_src_warehouse_id_fkey | stk_warehouse Stk_warehouse_part_log | part_id | 0 bytes | stk_warehouse_part_log_part_id_fkey | stk_part ![]() Stk_warehouse_part_log | dst_warehouse_id | 0 bytes | stk_warehouse_part_log_dst_warehouse_id_fkey | stk_warehouse Stk_warehouse_part | part_id | 0 bytes | stk_warehouse_part_part_id_fkey | stk_part Stk_part_reference | reference_id | 0 bytes | stk_part_reference_reference_id_fkey | stk_reference Stk_reference | supplier_id | 0 bytes | stk_reference_supplier_id_fkey | stk_supplier Stk_warehouse | supplier_id | 8192 bytes | stk_warehouse_supplier_id_fkey | stk_supplier referencing_table | fk_columns | table_size | fk_constraint | referenced_table Test it this way, select * from missing_fk_indexes() Pg_catalog.pg_relation_size(tc.conrelid) desc the first index columns must be the same as the key columns, but order doesn't matter is there ta matching index for the constraint? Join pg_catalog.pg_attribute ta on ta.attnum = tx.attnum and ta.attrelid = tc.conrelid enumerated key column numbers per foreign keyĬross join lateral unnest(tc.conkey) with ordinality as tx(attnum, n) Tc.confrelid::regclass as referenced_table name of the target or destination table String_agg(ta.attname, ', ' order by tx.n) as fk_columns, Tc.conrelid::regclass as referencing_table, referencing table having ta foreign key declaration author: Based on the work of Laurenz AlbeĬreate or replace function missing_fk_indexes () purpose: List all foreing keys in the database without and index in the referencing table. The size of the table is shown, as for small tables the scanning performance could be superior to the index one. ![]() This function, based on the work by Laurenz Albe at, list all the foreign keys with missing indexes. ORDER BY issue_sort, table_mb DESC, table_name, fk_name Round(pg_relation_size(conrelid)/(1024^2)::numeric) as table_mb,ĪND (indkey::int2) key_cols JOIN pg_class ON indexrelid = pg_class.oidĪrray_length(key_cols, 1) as fk_colcount,Īrray_length(indkey,1) as index_colcount, SELECT fkoid, array_agg(attname) as cols_list JOIN fk_actions AS fk_actions_delete ON confdeltype = fk_actions_de JOIN fk_actions AS fk_actions_update ON confupdtype = fk_actions_de JOIN pg_namespace ON pg_class.relnamespace = pg_namespace.oid SELECT pg_constraint.oid as fkoid, conrelid, confrelid as parentid,įk_actions_update.action as update_action,įk_actions_delete.action as delete_action, check for FKs where there is no matching index This query will list missing indexes on foreign keys, original source.Įdit: Note that it will not check small tables (less then 9 MB) and some other cases. If the index is rarely used it may not be worth having. Each index you add slows DML operations down slightly, so you pay a performance cost on every INSERT, UPDATE or DELETE. While it's usually a good idea to create an index on (or including) your referencing-side foreign key columns, it isn't required. Note that if you use primary-foreign-keys, like 2 FK's as a PK in a M-to-N table, you will have an index on the PK and probably don't need to create any extra indexes. ![]() Therefore you have to create indexes on foreign-keys yourself if you want them. Many choices available on how to index, declaration of a foreign keyĬonstraint does not automatically create an index on the referencing Because this is not always needed, and there are Rows matching the old value, it is often a good idea to index the ![]() Referenced column will require a scan of the referencing table for Since a DELETE of a row from the referenced table or an UPDATE of a Thus, it is not necessary to create an index explicitly for primary key columns.Īnd the documentation on constraints says: PostgreSQL automatically creates an index for each unique constraint and primary key constraint to enforce uniqueness. The documentation on unique indexes says: Automatically created indexes are visible in \d output for a table, too. When Pg creates an implicit index it will emit a NOTICE-level message that you can see in psql and/or the system logs, so you can see when it happens. PostgreSQL automatically creates indexes on primary keys and unique constraints, but not on the referencing side of foreign key relationships. ![]()
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