Andreas Kretschmer <andreas@a-kretschmer.de> wrote on 03/28/2019 07:28:53 AM:
> >
> > Ummm... Will it use an index (a BTree index)?
> >
>
> test=# explain select * from emp where ename = 'aaa';
> QUERY PLAN
> -----------------------------------------------------
> Seq Scan on emp (cost=0.00..25.88 rows=6 width=36)
> Filter: (ename = 'aaa'::citext)
> (2 rows)
>
> test=*# set enable_seqscan to off;
> SET
> test=*# explain select * from emp where ename = 'aaa';
> QUERY PLAN
> ------------------------------------------------------------------------
> Seq Scan on emp (cost=10000000000.00..10000000025.88 rows=6 width=36)
> Filter: (ename = 'aaa'::citext)
> (2 rows)
>
> test=*# create index emp_ename on emp(ename);
> CREATE INDEX
> test=*# explain select * from emp where ename = 'aaa';
> QUERY PLAN
> ----------------------------------------------------------------------
> Index Scan using emp_ename on emp (cost=0.13..8.14 rows=1 width=36)
> Index Cond: (ename = 'aaa'::citext)
> (2 rows)
I used citext heavily in a past project and was quite happy with it. It was never a source of performance issues.
Brad.