I just ran into an issue where I thought a query that was being dynamically
built was hanging. After checking the DB for the query, i don't see any of
the where clauses in the one that was hung. What I saw was:
`SELECT * FROM table_name LIMIT 1`
So then I saw this conditional that had me wondering...
`if query.columns.include?(x)`
so I looked at the docs and saw that the columns function does actually run
the query that was being hung. It never actually reached my dynamic query's
execution point.
>From previous experience in postgresql, I found that in largely populated
tables, when running a query with a `LIMIT` clause and no `ORDER BY`, there
are big performance implications. So even if I don't know the potential
columns, or I don't really care about the order, I will still add an ORDER
clause.
`SELECT * FROM my_table ORDER BY RANDOM() LIMIT 1`
I was wondering if anyone had thoughts on this or had any similar issues.
For now I am simply doing a workaround by adding a `column_names()` method
via a plugin to all my models.
```
def column_names
table = self.table_name
columns = DB.fetch("SELECT column_name from information_schema.columns
where table_schema = 'my_schema' and table_name = '#{table}'").all
columns.map { |i| i[:column_name].to_sym }
end
```
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