You were using the wrong join.
Your snippet is moving computation from a database
server to a client application, and it's doing that
whitout any particular need.
The canonical way of transforming your query should
go through a table JOIN. However, since you are subquerying
the same table, your nested query is nothing more
than this:
select object_id from mw_export_record
where table_object != 'advertisers'; -- <-- operator change
The inner part of your query is selecting all the IDs
containing 'advertisers', while the outer part is saying
"don't take any record from this list."
Not only you are computing in the client what should
be done in the server, but you are also telling the
server to do something unnecessarily complex and heavy
that it should not have been doing in the first place.
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