Informix V12 Fragmentation
In previous versions of Informix IDS - I believe that if you included a 'remainder' clause in a table fragmentation statement, that queries over that table would not have any fragment elimination (assuming that a where clause has filters that matched fragmentation scheme). Is that still true in Version 12.x?
A quick test in version 11.70.FC7W1 (see below) shows that fragment
elimination works properly and I am sure it worked fine in 11.50 and very
likely in earlier versions too.
create table test (col1 int
) fragment by expression
col1 = 0 in dbspace1,
col1 between 1 and 3 in dbspace2,
col1=4 in dbspace3,
remainder in dbspace4
;
insert into test values (0);
insert into test values (1);
insert into test values (2);
insert into test values (3);
insert into test values (4);
insert into test values (5);
set explain on;
select * from test where col1=0;
QUERY: (OPTIMIZATION TIMESTAMP: 10-20-2014 16:09:25)
------
select * from test where col1=0
Estimated Cost: 2
Estimated # of Rows Returned: 1
1) ben.test: SEQUENTIAL SCAN (Serial, fragments: 0)
Fragments Scanned: (0) dbspace1
Filters: ben.test.col1 = 0