GForce should kick in when `i` is present as well...
Nobody has claimed this yet.
Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 35/100
- Issue type
- Feature
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- r
- Domain
- data-engineering
Research direction
No files or tests are named. Reproduce the supplied data.table example with verbose output, then trace the GForce optimization path for a query with a subset in i. Done means the filtered mean query uses GForce as expected; join behavior remains marked separately in the issue.
Written by the indexing model from the issue text.
Description
require(data.table) # 1.9.5, R v3.1.2
DT = data.table(x=c(1,1,1,2,2,3,3,3), y=1:8)
options(datatable.verbose=TRUE)
# GForce kicks in
DT[, mean(y),by=x]
# Detected that j uses these columns: y
# Finding groups (bysameorder=FALSE) ... done in 0secs. bysameorder=TRUE and o__ is length 0
# lapply optimization is on, j unchanged as 'mean(y)'
# GForce optimized j to 'gmean(y)'
# x V1
#1: 1 2.0
#2: 2 4.5
#3: 3 7.0
# GForce doesn't
DT[x > 1L, mean(y), by=x]
# i clause present and columns used in by detected, only these subset: x
# Detected that j uses these columns: y
# Finding groups (bysameorder=FALSE) ... done in 0secs. bysameorder=TRUE and o__ is length 0
# lapply optimization is on, j unchanged as 'mean(y)'
# Old mean optimization changed j from 'mean(y)' to '.External(Cfastmean, y, FALSE)'
# Starting dogroups ...
# collecting discontiguous groups took 0.000s for 2 groups
# eval(j) took 0.000s for 2 calls
# done dogroups in 0 secs
# x V1
#1: 2 4.5
#2: 3 7.0
- subsets in
i - joins in
i
- Dominant language
- R
- Stars
- 3.9k
- Forks
- 1.1k
- Avg merge
- 14h 4m
- Merged PRs (30d)
- 4
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