On 24-2-2018 11:40, [email protected] [firebird-support] wrote: > I am having a doubt that if Foreign Key reduces Query Performance Or not. > > My Environment is > > FirebirdCS2.6 :- > > Item Table :- 10 Records, PK - Itemcode Varchar(5); > > BillDetail Table :- 10 Million Records (FK Selectivity - 0.0076, PK > Selectivity - 0.000000076) > > > I am having FK between BillDetail.Itemcode And Item.Itemcode with FK > every query is slow. but as i remove the FK and added Index with > Itemcode&BillDetail_PK the queries are running lightning fast. But I > prefer FK to be in Database with high performance queries.
It could mean the statistics on the index of the primary key or foreign key are not up-to-date, so Firebird doesn't take the index into consideration. Try updating the index statistics, see also http://www.firebirdfaq.org/faq167/ If it still doesn't work, we need more information, like the full DDL, the query and the execution plan in both situations. Mark -- Mark Rotteveel
