On Thursday, April 26, 2018 at 7:41:42 AM UTC-7, [email protected]
wrote:
>
> Sorry for my super response here. I actually began work on a sequel-drill
> driver, but this project has sort of been on-again-off-again. Definitely
> committed to seeing this through now and getting this over the finish line:
>
> https://github.com/joeauty/sequel-drill
>
> A question I have for the community:
>
> The above driver is a little crude on account of it being my first go at
> writing this, but also because it sort of generates table names in SQL
> statements in a rather hacky way (regex). Do you have any tips for an
> abstraction layer I can override/plug into that would help? Basically,
> normally a SQL statement would be in the format:
>
> select * from <table name>
>
> where Drill needs this to be:
>
> select * from dfs.<workspace>.`<table name>`
>
> The workspace I'm deriving from the connection string (it is sort of a
> conceptual database), but the big challenge is basically adding this entire
> preface and wrapping it in backticks. My regex does work, but obviously it
> will be messy to keep tacking on new regex for new sort of query support
> (e.g. join statements). It would be lovely to be able to do this in one
> place overriding some sort of abstraction where table names are generated.
>
> Do you have any suggestions for how I might go about this, whether this is
> in the form of a Sequel PR, or something that can be done in my driver
> without modifications to the parent project?
>
I would override Dataset#from and Dataset#join_table.:
DB.extend_datasets do
def from(*sources)
sources.map!{|table| wrap_table(table)}
super
end
def join_table(type, table, *args)
table = wrap_table(table)
super
end
private
def wrap_table(table)
case table
when Symbol, Sequel::SQL::Identifier
Sequel.qualify(Sequel.qualify(Sequel.lit('dfs'),
Sequel.lit(db.opts[:workspace])), table)
else
table
end
end
end
That should handle the most common places where table names are used. If
there are other cases, you can call wrap_table in those cases as well. I
don't want to include direct support for this type of mangling in Sequel.
Thanks,
Jeremy
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