OID-related error

[daniel-perry]

I have the following database:

https://physionet.org/mimic2/demo/

I can run simple queries fine, when I run a more complicated query like this:

querystr = """select bucket, count(*) from (
select months_between(mimic2v26.admissions.admit_dt::timestamp::date, mimic2v26.d_patients.dob::timestamp::date)/12 from mimic2v26.admissions, mimic2v26.d_patients, 
width_bucket(
months_between(mimic2v26.admissions.admit_dt::timestamp::date,
mimic2v26.d_patients.dob::timestamp::date)/12, 
15, 100, 85) 
as bucket 
where mimic2v26.admissions.subject_id = mimic2v26.d_patients.subject_id 
and 
months_between(mimic2v26.admissions.admit_dt::timestamp::date,
mimic2v26.d_patients.dob::timestamp::date)/12 between 15 and 199
) 
as 
bucket 
group by bucket order by bucket;"""

stmt = prepare(conn, querystr)
result = execute(stmt)

I get the following error:

LoadError: MethodError: `convert` has no method matching convert(::Type{PostgreSQL.PostgresType{Name}}, ::Type{PostgreSQL.OID{2249}})
This may have arisen from a call to the constructor PostgreSQL.PostgresType{Name}(...),
since type constructors fall back to convert methods.
Closest candidates are:
  call{T}(::Type{T}, ::Any)
  convert(::Type{PostgreSQL.PostgresType{Name}}, !Matched::Type{PostgreSQL.OID{16}})
  convert(::Type{PostgreSQL.PostgresType{Name}}, !Matched::Type{Bool})
  ...
while loading In[5], in expression starting on line 17

This query works fine in both psql and via psycopg2.

Digging around it appears OID's are a little used feature of PosgreSQL (http://www.postgresql.org/docs/8.4/interactive/runtime-config-compatible.html#GUC-DEFAULT-WITH-OIDS), which might be why PostgreSQL.jl is having trouble converting a result using OID. But since psycopg2 supports them, I though it was worth opening the issue.

Julia version: Version 0.4.2 (2015-12-06 21:47 UTC)

[iamed2]

OID's are actually used all over PostgreSQL for many things; in this case, OIDs are being used for denoting the type of the data, which is a very common use. Basically I have no type conversion defined for PostgreSQL's RECORD type (which is itself just a placeholder for the type of any record). I'm not sure if I even have a good idea of what to do with record types off the top of my head.

Eventually I do need to address all OIDs so these problems stop happening. I have been unable to work on PostgreSQL due to other projects dominating my time, but this will change March 1 and I'll devote most of my time to PostgreSQL again. In the meantime, I'm open to PRs if you have an idea on how to deal with RECORD types.