Moi Verhole

PostgreSQL uses several memory components for each unique usage. That is, it uses
dedicated memory areas for transactions, sort/join operations, maintenance operations, and
so on. If the configured memory component doesn't fit the usage of the live application,
then we may hit a performance issue, where PostgreSQL tries for more I/O.

The following are the query planning related parameters that usually require tuning:
random_page_cost
seq_page_cost
effective_cache_size
work_mem
constraint_exclusion
These parameters can be set in the postgresql.conf configuration file.

In this case, there will be either a duplicate key violation or two identical entries. Neither
variation of the problem is all that appealing.

Transaction 1
BEGIN;
SELECT max(id) FROM product;
User will see 17；
User will decide to use 18；
INSERT INTO product ... VALUES (18,
...)
COMMIT;

Transaction 2
BEGIN;
SELECT max(id) FROM product;
User will see 17；
User will decide to use 18；
INSERT INTO product ... VALUES (18,
...)
COMMIT;

Given a sorted array of integers a, find an integer x from a such that the value of

abs(a[0] - x) + abs(a[1] - x) + ... + abs(a[a.length - 1] - x)
is the smallest possible (here abs denotes the absolute value).
If there are several possible answers, output the smallest one.

**Example**

For a = [2, 4, 7], the output should be
absoluteValuesSumMinimization(a) = 4.

For a = [2, 4, 7, 6], the output should be
absoluteValuesSumMinimization(a) = 4.