Searching each element of array using like - sql

Question

I would like some professional advice regarding my problem.
You see our database is using an ETL to retrieve massive data. Some or rather most of these data are aggregated.
Problem is I need to retrieve a data, base on the selected Stations
For example. I selected MNL.
Now, in aggregated column we have arrays like:
{MNL-CEB,CEB-MNL,DVO-MNL,MNL-DVO,DVO-CEB,CEB-DVO}
Now, given with my selected code (MNL), I should only be able to pick the following elements from the array.
MNL-CEB,
CEB-MNL,
DVO-MNL,
MNL-DVO
I've been trying various where conditions with no success. Hope you guys can help me out. Thanks!
Here's a piece of code I've been using below -
select distinct
unnest(fpd.segment_agg) segments
from daylightreport.f_dailysales_agg fpd
The data is too big to unnest, causing the script to load more.
Edit - I'm also using more than 1 station code. For instance
Where fpd.segment_agg IN ('MNL','CEB') or something similar to this.
Thanks in advance!

Answer 1

One way that avoids unnesting is to convert the array to a string then do a regex match on that string:
select *
from daylightreport.f_dailysales_agg fpd
where array_to_string(fpd.segment_agg, ',') ~ '(-){0,1}(MNL)(-){0,1}';
The regex makes sure the search string doesn't appear as part of another string. If that can't happen anyway, a simple like would probably do as well. This also assumes that the data never contains a ,
This is not going to be fast though, but avoids the unnesting in multiple rows.
Another option (although probably not really that much faster) is to write a function that loops through the array elements and uses the LIKE operator:
create or replace function any_element_like(p_elements text[], p_pattern text)
returns boolean
as
$$
declare
l_word text;
begin
foreach l_word in array p_elements
loop
if l_word like p_pattern then
return true;
end if;
end loop;
return false;
end;
$$
language plpgsql;
That could be used like this:
select *
from daylightreport.f_dailysales_agg fpd
where any_element_like(fpd.segment_agg, '%MNL%');