Hi all, PostgreSQL v8.0.0rc1, two variants of a "user_msg" table:
create table user_msg ( message_id integer not null references message(id) on update cascade on delete cascade, user_id integer not null, status smallint not null default 0, is_read boolean not null default false, unique (message_id,user_id) ); create index user_msg_is_read_idx on user_msg(is_read) where is_read=true; create table user_msg ( message_id integer not null references message(id) on update cascade on delete cascade, user_id integer not null, status smallint, is_read boolean, unique (message_id,user_id) ); create index user_msg_is_read_idx on user_msg(is_read) where is_read=true; In both cases, tables are filled with ~10m of rows, "is_read" is false in the 1st case, and "NULL" in the 2nd. I did "VACUUM FULL ANALYSE" after both imports. Here's the problem: in the 2nd case, planner wouldn't choose an index scan using partial index on "is_read" for the following queries: explain select * from user_msg where is_read=true; explain select * from user_msg where is_read is true; explain select * from user_msg where is_read; In the 1st case, partial index was used for the first query. -- Best Regards, Igor Shevchenko ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]