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queryverse / QuerySQLite.jl

SQLite backend for Query.jl
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@mapmany missing? #35

Open tlnagy opened 4 years ago

tlnagy commented 4 years ago

Using master, it looks like the @mapmany command is missing. For the groupby and then split approach mapmany is critical, is it just not implemented? I didn't see it mentioned in the codebase.

julia> db = SQLite.DB("data.sqlite3");

julia> getproperty(db, tbl[1]) |>
    @groupby(_.cell_id) |>
     # filter stuff
    @map({cell_id=key(_), rows=_}) |>
    @mapmany(i->i.rows, (i, j)->{j...}) |>
    DataFrame;
MethodError: no method matching mapmany(::QuerySQLite.SourceCode{SQLite.DB}, ::var"#113#123", ::Expr, ::var"#114#124", ::Expr)
Closest candidates are:
  mapmany(!Matched::QueryOperators.Enumerable, ::Function, ::Expr, ::Function, ::Expr) at /home/tlnagy/.julia/packages/QueryOperators/g4G21/src/enumerable/enumerable_mapmany.jl:42

Stacktrace:
 [1] (::var"#112#122")(::QuerySQLite.SourceCode{SQLite.DB}) at /home/tlnagy/.julia/packages/Query/AwBtd/src/standalone_query_macros.jl:205
 [2] |>(::QuerySQLite.SourceCode{SQLite.DB}, ::var"#112#122") at ./operators.jl:823
 [3] top-level scope at In[30]:1
bramtayl commented 4 years ago

Nope, just not implemented, but shouldn't be too hard. Do you happen to know what the corresponding SQL code would look like?

tlnagy commented 4 years ago

I'm pretty new to SQL, but maybe the UNIONALL command is what we're looking for? I'm not sure it covers all of @mapmany's functionality.

bramtayl commented 4 years ago

Hmm, I'm not sure that would do it...do you think you could come up with an example of using @mapmany using the Chinook_Sqlite.sqlite data in the test folder of the package (reading it into julia first, maybe as a dataframe). Then I'll see if I can replicate it in SQL?