gaberudy / rcppleveldb

Rcpp bindings for Google's leveldb

RcppLevelDB

RcppLevelDB is a Rcpp based LevelDB binding for R

Support for iterators was added by Gabe Rudy.

Dependencies

• leveldb, leveldb C++ library, e.g. via libleveldb-dev on Debian or Ubuntu
• Rcpp for seamless R and C++ integration
• RApiSerialize for C-level serialization from the R API

Getting Started

library(RcppLevelDB)

ldb <- new(LevelDB, 'my-leveldb') #creates the DB, if not exists

ldb$Put('key1', list(a=c(1,2,3), b='sometext', c=42))
#>[1] TRUE
ldb$Put('anotherkey', 'somevalue')
#>[1] TRUE

#vectorized Get & Delete operations
ldb$Get(c('key1', 'anotherkey'))
#>[[1]]
#>[[1]]$a
#>[1] 1 2 3
#>
#>[[1]]$b
#>[1] "sometext"
#>
#>[[1]]$c
#>[1] 42
#>
#>
#>[[2]]
#>[1] "somevalue"
#>

#Iteration
ldb$StartIteration()
#>[1] TRUE
ldb$IterNext()
#>[[1]]
#>[1] "anotherkey"
#>
#>[[2]]
#>[1] "somevalue"
#>
> ldb$IterNext()
#>[[1]]
#>[1] "key1"
#>
#>[[2]]
#>[[2]]$a
#>[1] 1 2 3
#>
#>[[2]]$b
#>[1] "sometext"
#>
#>[[2]]$c
#>[1] 42
#>
ldb$IterNext()
#>[[1]]
#>[1] NA
#>
#> 

#Deletion
ldb$Delete(c('key1', 'anotherkey'))
#>[1] TRUE TRUE
ldb$Get(c('key1', 'anotherkey'))
#>[[1]]
#>[1] NA
#>
#>[[2]]
#>[1] NA
#>
rm(ldb) #to close the database safely
gc() # remove all handles

TODO

• Expose Options/ReadOptions/WriteOptions structs to R
• Add default arguments to constructor and Put/Get/Delete methods e.g. create_if_missing=TRUE, sync=FALSE etc.
• Add support for BloomFilter policies, WriteBatch, and Iterators
• Add RepairDB and DestroyDB functions
• Something like Structured Get operation: create a data.frame out of values of the given query keys, when the values have a pre-defined structure
• plyvel is a nice leveldb binding example to get some influence regarding new features

Author

Gökcen Eraslan, based on RcppRedis by Dirk Eddelbuettel

License

GPL (>= 2)