Matt I made a much simpler example that only involves the first data.table
Also, although I had a POSIX date before, this example just has the text for the date. It appears that the longer text columns are causing a problem. I'm saving as an RData file, and I also try using Rds at the end, but with no difference. Now I'm more convinced that the problem is in data.table, but I'm not ruling out user error. > ## I was able to reproduce a simpler example > ## without the second data.table > > ## Here is the data (with generic column names) > str(datMod) Classes ‘data.table’ and 'data.frame': 3103314 obs. of 41 variables: $ char1 : chr "http://conradhotels3.hilton.com"; " http://conradhotels3.hilton.com"; "http://conradhotels3.hilton.com"; " http://conradhotels3.hilton.com"; ... $ char2 : chr "/en/index.html" "/en/index.html" "/en/index.html" "/en/index.html" ... $ char3 : chr "" "" "" "" ... $ int1 : int 44903 44903 44903 44903 44903 44903 44903 44903 44903 44903 ... $ int2 : int 411 411 254 254 336 336 118 118 386 386 ... $ char4 : chr "2012-05-09 20:17:40.587" "2012-05-09 21:17:54.427" "2012-05-09 20:10:49.560" "2012-05-09 21:11:05.107" ... $ int3 : int 0 0 0 0 0 0 0 0 0 0 ... $ int4 : int 0 0 0 0 0 0 0 0 0 0 ... $ int5 : int 69 69 69 69 69 69 69 68 68 68 ... $ int6 : int 68 68 68 68 68 68 68 67 67 67 ... $ int7 : int 35 35 37 35 35 35 33 38 38 40 ... $ int8 : int 0 0 0 0 0 0 0 0 0 0 ... $ int9 : int 0 0 0 0 0 0 0 0 0 0 ... $ int10 : int 0 0 0 0 0 0 0 0 0 0 ... $ int11 : int 1 1 1 1 1 1 1 1 1 1 ... $ int12 : int 334830 334847 335102 334838 334836 342687 334521 318626 318578 326800 ... $ int13 : int 36 36 37 36 36 36 35 38 37 39 ... $ int14 : int 44 44 49 47 45 45 45 46 45 48 ... $ char5 : chr "" "" "" "" ... $ int15 : int NA NA NA NA NA NA NA NA NA NA ... $ int16 : int 0 0 0 0 0 0 0 0 0 0 ... $ int17 : int 0 0 0 0 0 0 0 0 0 0 ... $ int18 : int 2 2 2 2 2 2 2 2 2 2 ... $ int19 : int 1381 1152 424 3728 1772 921 385 725 401 314 ... $ int20 : int 36 36 37 36 36 36 35 38 37 39 ... $ int21 : int 2199 2201 1492 1448 2559 2529 1084 1432 1876 1984 ... $ int22 : int 44 44 49 47 45 45 45 46 45 48 ... $ int23 : int 2203 2188 1199 1162 2324 2346 821 897 1386 1189 ... $ int24 : int 13 13 14 13 13 13 12 13 13 14 ... $ int25 : int 5166 5761 3755 3794 5614 7779 2830 3971 4637 5871 ... $ int26 : int 103 103 105 103 103 103 101 105 105 107 ... $ int27 : int 70 183 159 197 217 165 153 232 92 102 ... $ int28 : int 103 103 105 103 103 103 101 105 105 107 ... $ int29 : int 0 0 0 0 0 0 0 0 0 0 ... $ int30 : int 161 146 200 158 150 160 190 161 163 169 ... $ char6 : chr "Limelight" "Limelight" "Fusepoint/Savvis" "Fusepoint/Savvis" ... $ char7 : chr "Paris" "Paris" "Toronto" "Toronto" ... $ char8 : chr "-1" "-1" "-1" "-1" ... $ char9 : chr "FRANCE" "FRANCE" "CANADA" "CANADA" ... $ char10: chr "FR" "FR" "CA" "CA" ... $ char11: chr "FRANCE" "FRANCE" "CANADA" "CANADA" ... - attr(*, ".internal.selfref")=<externalptr> > > ## Here is the size when you save that file > save(datMod, file='test0.Rdata') > originalfilesize = file.info('test0.RData')$size > formatC(originalfilesize, big.mark=',', format='f', digits=0) [1] "71,085,933" > > ## Here is the size after you set the key > setkey(datMod, char4) > save(datMod, file='test1.Rdata') > newfilesize = file.info('test1.RData')$size > formatC(newfilesize, big.mark=',', format='f', digits=0) [1] "195,406,633" > > ## Some of the columns have a large size > datMod[,range(nchar(char2))] [1] 1 1606 > datMod[,range(nchar(char3))] [1] 0 2048 > > ## If I remove the long columns it helps reduce the file size > datMod$char2 = NULL > datMod$char3 = NULL > > save(datMod, file='test2.Rdata') > secondfilesize = file.info('test2.RData')$size > formatC(secondfilesize, big.mark=',', format='f', digits=0) [1] "121,237,355" > > ## Using RDS doesn't matter > saveRDS(datMod, file='test2.Rds') > secondfilesizeRDS = file.info('test2.Rds')$size > formatC(secondfilesizeRDS, big.mark=',', format='f', digits=0) [1] "121,237,288"
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