# First steps in JuliaDB

**URL:** <https://discourse.julialang.org/t/first-steps-in-juliadb/14010>\
**Category:** Data\
**Tags:** question\
**Created:** [August 24, 2018, 6:31pm UTC](https://discourse.julialang.org/t/first-steps-in-juliadb/14010 "2018-08-24T18:31:33Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![jstrube](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jstrube/32/525_2.png) [@jstrube](https://discourse.julialang.org/u/jstrube)\
**Post date:** [August 24, 2018, 6:31pm UTC](https://discourse.julialang.org/t/first-steps-in-juliadb/14010/1 "2018-08-24T18:31:33Z")

</div>

I’m taking first steps with JuliaDB, but I’m already falling on my face. My first stumble was the difference between `loadtable` and `load`. Why do I need a different method name for a different input format? Moving on…  
I’m now trying to perform some simple operations on the table. For example:

```julia
tb = load("Digits") 
Distributed Table with 66889667 rows in 10 chunks:
Columns:
# colname type
───────────────────────
1 idx Int64
2 mcpidx Int64
3 pixelID Int64
4 time Float64
5 x Float64
6 y Float64
7 z Float64
8 px Float64
9 py Float64
10 pz Float64
11 thetaC Float64
12 localTheta Float64
13 localPhi Float64

```

but:

```julia
select(tb, :x)
MethodError: Dagger.distribute(::Dagger.DArray{Int64,1,JuliaDB.##58#60}, ::Dagger.DomainBlocks{1}) is ambiguous. Candidates:
  distribute(source, rowgroups::AbstractArray) in IterableTables at /home/ilc/jstrube/.julia/v0.6/IterableTables/src/integrations/juliadb.jl:19
  distribute(x::AbstractArray, dist) in Dagger at /home/ilc/jstrube/.julia/v0.6/Dagger/src/array/darray.jl:390
Possible fix, define
  distribute(::AbstractArray, ::AbstractArray)

Stacktrace:
 [1] macro expansion at /home/ilc/jstrube/.julia/v0.6/NamedTuples/src/NamedTuples.jl:289 [inlined]
 [2] _map(::JuliaDB.##39#43, ::NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60}}) at /home/ilc/jstrube/.julia/v0.6/NamedTuples/src/NamedTuples.jl:276
 [3] #table#37(::Void, ::Array{Any,1}, ::Function, ::Val{:distributed}, ::NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60}}) at /home/ilc/jstrube/.julia/v0.6/JuliaDB/src/table.jl:90
 [4] (::IndexedTables.#kw##table)(::Array{Any,1}, ::IndexedTables.#table, ::Val{:distributed}, ::NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60}}) at ./<missing>:0
 [5] #table#104(::Void, ::Array{Any,1}, ::Function, ::NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60}}) at /home/ilc/jstrube/.julia/v0.6/IndexedTables/src/table.jl:247
 [6] (::IndexedTables.#kw##table)(::Array{Any,1}, ::IndexedTables.#table, ::NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Int64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60},Dagger.DArray{Float64,1,JuliaDB.##58#60}}) at ./<missing>:0
 [7] #table#107(::Array{Symbol,1}, ::Array{Any,1}, ::Function, ::Dagger.DArray{Int64,1,JuliaDB.##58#60}, ::Vararg{AbstractArray,N} where N) at /home/ilc/jstrube/.julia/v0.6/IndexedTables/src/table.jl:259
 [8] (::IndexedTables.#kw##table)(::Array{Any,1}, ::IndexedTables.#table, ::Dagger.DArray{Int64,1,JuliaDB.##58#60}, ::Dagger.DArray{Int64,1,JuliaDB.##58#60}, ::Dagger.DArray{Int64,1,JuliaDB.##58#60}, ::Vararg{AbstractArray,N} where N) at ./<missing>:0
 [9] getindex(::IndexedTables.ColDict{JuliaDB.DNextTable{NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Int64,Int64,Int64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64},Tuple{Int64}}}) at /home/ilc/jstrube/.julia/v0.6/IndexedTables/src/table.jl:360
 [10] select(::JuliaDB.DNextTable{NamedTuples._NT_idx_mcpidx_pixelID_time_x_y_z_px_py_pz_thetaC_localTheta_localPhi{Int64,Int64,Int64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64,Float64},Tuple{Int64}}, ::Symbol) at /home/ilc/jstrube/.julia/v0.6/IndexedTables/src/selection.jl:131

```

I don’t dispute that a 66-million-entry vector may not be immediately useful for further exploration, but I don’t understand what this error message is trying to tell me.

---

<div class="post-metadata">

**Author:** ![joshday](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/joshday/32/368_2.png) [@joshday](https://discourse.julialang.org/u/joshday)\
**Post date:** [February 4, 2019, 9:09pm UTC](https://discourse.julialang.org/t/first-steps-in-juliadb/14010/2 "2019-02-04T21:09:31Z")

</div>

Sorry, I wish I hadn’t missed this when you posted.

A lot has happened inside JuliaDB since then. Does the error still occur in the latest release?