On Thu, Oct 24, 2024 at 12:53 PM Sbob <sbob@xxxxxxxxxxxxxxxxxxxxx> wrote:
All;
I created a table that includes a lastname column that is a varchar(50) :
CREATE TABLE customers (
cust_id bigint,
custinfo text,
cust_dob date,
lastname varchar(50),
firstname varchar(50),
custaddr varchar(200),
city varchar(100),
state varchar(100),
zipcode varchar(5)
) PARTITION BY LIST (lastname) ;
Then we created 4,000 partitions with each partition hosting a specific
set of lastname's (each partition has 100 lastname's)
The partitions are all based on UPPER(lastname) like this:
CREATE TABLE cust_part1
PARTITION OF customer
FOR VALUES IN ('SMITH', 'JONES','REX', 'ROBINSON', 'ROBINSON JR' ... )
and all the partitions have been loaded up with all the data that lines
up with the partition key (100 lastnames per partition)
Each partition has an INDEX on upper(lastname)
When I run something like :
EXPLAIN SELECT * FROM customers where lastname = 'BORRIS';
The explain plan does an index scan on each partition even though
constraint_exclusion os set to "partition"
Thanks in advance for any advice
Since your index is functional, in order to use the index, the queries must use that same function in the condition. Try doing
EXPLAIN SELECT * FROM customers where lastname = upper('BORRIS');
EXPLAIN SELECT * FROM customers where lastname = upper('BORRIS');
or this should give the same result
EXPLAIN SELECT * FROM customers where lastname = upper('borris');
