Adding +0 or || '' (depending on type of field_A) would make it more likely that the table_B.field_B index will be used. It wouldn't force the optimizer, just be a strong hint...
Select * from table_A a left join table_B b on a.field_A = b.field_A+0 where b.field_B = 1 HTH, Set Den tor. 7. mar. 2019 kl. 12:32 skrev Carsten Schäfer ca_schae...@gmx.de [firebird-support] <firebird-support@yahoogroups.com>: > > > Yes I'm sure. > > With the left join FB does a full scan on Table_A and uses the Foreign Key > index on Table_B. The index on table_B.field_B is not used at all. > > So you get millions of reads if the table contains millions of data > > With the inner join the index on table_B.field_B is used and you only > get 1 read (if It's only 1 row that matches the condition) > > Is it possible to force the optimizer tu use the index on table_B.field_B? > > > Regards > Carsten > > > Am 06.03.2019 um 21:49 schrieb Karol Bieniaszewski > liviusliv...@poczta.onet.pl [firebird-support]: > > > > Are you sure that this query looks like this? > > > > For me such query use indexes in both cases left and inner. > > Show full example with plans > > > > Regards, > > Karol Bieniaszewski > > > >
