RJDBC wrongly reading bigintegers from database table

问题

I am retrieving a column containing big integers from a data base into R (using RJDBCs dbGetQuery method). For a test case, one can consider the following numbers

1000522010609612 
1000522010609613 
1000522010609614 
1000522010609615 
1000522010609616 
1000522010609617 
**971000522010609612 
1501000522010819466 
971000522010943717 
1501000522010733490**

R seems to be reading the contents wrongly. The way in which it is available to me in R (after I read from the database using RJDBC) is:

1000522010609612
1000522010609613
1000522010609614
1000522010609615
1000522010609616
1000522010609617
**971000522010609664
1501000522010819584
971000522010943744
1501000522010733568**

See the last 4 numbers. They are wrong! It seems to be automatically converting the data into a dataframe (which is fine - but) with the corrupted numbers (for bigints). Any suggestion on how we can solve the above problem particularly when we are using dbGetQuery using RJDBC package?

回答1:

Your data is read in as floating point numbers:

DF <- read.table(text="1000522010609612 
1000522010609613 
1000522010609614 
1000522010609615 
1000522010609616 
1000522010609617 
971000522010609612 
1501000522010819466 
971000522010943717 
1501000522010733490")

class(DF[,1])
#[1] "numeric"
sprintf("%20f", DF[10, 1])
#[1] "1501000522010733568.000000"

You could read it as strings and convert to big integers or read in as big integers directly:

library(bit64)

DF <- read.table(text="1000522010609612 
1000522010609613 
1000522010609614 
1000522010609615 
1000522010609616 
1000522010609617 
971000522010609612 
1501000522010819466 
971000522010943717 
1501000522010733490", colClasses = "integer64")

#                    V1
#1     1000522010609612
#2     1000522010609613
#3     1000522010609614
#4     1000522010609615
#5     1000522010609616
#6     1000522010609617
#7   971000522010609612
#8  1501000522010819466
#9   971000522010943717
#10 1501000522010733490

I can't help you with your database application, but this should provide a starting point for solving your problem.

来源：https://stackoverflow.com/questions/27332693/rjdbc-wrongly-reading-bigintegers-from-database-table

标签

bigint

rjdbc