I have inserted a row that i don't touch, runned ANALYZE and tried again but with the same result. I'm using postgres 9.6.3 and EXPLAIN ANALYZE shows this:
Index Scan using users_username_idx on users (cost=0.13..8.14 rows=1 width=4) (actual time=0.020..0.020 rows=0 loops=1) Index Cond: (name = 'bob'::text) 2017-08-30 0:13 GMT+02:00 Thomas Munro <thomas.mu...@enterprisedb.com>: > On Wed, Aug 30, 2017 at 4:28 AM, Luca Looz <luca.loo...@gmail.com> wrote: > > I'm trying to use the serializable isolation but i'm getting read/write > > dependencies error even if i have an unique index on the column used and > the > > transactions are using different keys. > > For an example see this gist: > > https://gist.github.com/nathanl/f98450014f62dcaf0405394a0955e18e > > Is this an expected behavior? > > Take a look at the EXPLAIN plan for the SELECT. You'll get fine > grained SIREAD locks if it's doing a btree index scan, but table-level > SIREAD locks for other kinds of plans. Sometimes simple SSI tests can > show a lot of false positives just because of empty tables or missing > statistics (ANALYZE). > > -- > Thomas Munro > http://www.enterprisedb.com >
