TysonStanley opened a new issue, #43742:
URL: https://github.com/apache/arrow/issues/43742
### Describe the bug, including details regarding any error messages,
version, and platform.
When a data.table object is indexed (e.g., with `setindex()`), this can
cause problems in reading the parquet back in (`Error: IOError: Couldn't
deserialize thrift: TProtocolException: Exceeded size limit`) and it explodes
the size of the file (e.g., from 400MB to 2GB with the only change being the
index). See reprex below:
```r
library(data.table)
library(arrow)
dt<-data.table(x=c(1:1e8), y = round(runif(n=1:1e8, min=1, max=5)))
#Looking at rows where y == 3
dt[y == 3,]
#Creating a new variable, which is done uniformly across all rows
(suggesting the previous row index isn't applicable?)
dt[, z := 1]
#Save the dt
write_parquet(dt, "example.parquet")
gc()
#Cannot open the dt
dt_open<-read_parquet("example.parquet")
#Removing indexing that was created when looking at the y==3 subset before
saving allows
#the file to be opened after re-saving.
setindex(dt, NULL)
write_parquet(dt, "example2.parquet")
dt_open<-read_parquet("example2.parquet")
```
### Component(s)
Parquet, R
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