[SPARK-10981] R semijoin leads to Java errors, R leftsemi leads to Spark errors

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.5.0
• Fix Version/s: 1.5.2, 1.6.0
• Component/s: SparkR
• Labels: easyfix newbie

Environment

SparkR from RStudio on Macbook

• Assignee: Monica Liu
• Reporter: Monica Liu
• Created: 07/Oct/15 20:19
• Updated: 29/Dec/15 09:10
• Resolved: 14/Oct/15 05:26

Description

I am using SparkR from RStudio, and I ran into an error with the join function that I recreated with a smaller example:

joinTest.R

Sys.setenv(SPARK_HOME="/Users/liumo1/Applications/spark/")
.libPaths(c(file.path(Sys.getenv("SPARK_HOME"), "R", "lib"), .libPaths()))
library(SparkR)
sc <- sparkR.init("local[4]")
sqlContext <- sparkRSQL.init(sc) 

n = c(2, 3, 5)
s = c("aa", "bb", "cc")
b = c(TRUE, FALSE, TRUE)
df = data.frame(n, s, b)
df1= createDataFrame(sqlContext, df)
showDF(df1)

x = c(2, 3, 10)
t = c("dd", "ee", "ff")
c = c(FALSE, FALSE, TRUE)
dff = data.frame(x, t, c)
df2 = createDataFrame(sqlContext, dff)
showDF(df2)
res = join(df1, df2, df1$n == df2$x, "semijoin")
showDF(res)

Running this code, I encountered the error:

Error in invokeJava(isStatic = FALSE, objId$id, methodName, ...) :
java.lang.IllegalArgumentException: Unsupported join type 'semijoin'. Supported join types include: 'inner', 'outer', 'full', 'fullouter', 'leftouter', 'left', 'rightouter', 'right', 'leftsemi'.

However, if I changed the joinType to "leftsemi",

res = join(df1, df2, df1$n == df2$x, "leftsemi")

I would get the error:

Error in .local(x, y, ...) :
joinType must be one of the following types: 'inner', 'outer', 'left_outer', 'right_outer', 'semijoin'

Since the join function in R appears to invoke a Java method, I went into DataFrame.R and changed the code on line 1374 and line 1378 to change the "semijoin" to "leftsemi" to match the Java function's parameters. These also make the R joinType accepted values match those of Scala's.

semijoin:

DataFrame.R: join(x, y, joinExpr, joinType)

if (joinType %in% c("inner", "outer", "left_outer", "right_outer", "semijoin")) {
    sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc, joinType)
} 
else {
     stop("joinType must be one of the following types: ",
             "'inner', 'outer', 'left_outer', 'right_outer', 'semijoin'")
}

leftsemi:

DataFrame.R: join(x, y, joinExpr, joinType)

if (joinType %in% c("inner", "outer", "left_outer", "right_outer", "leftsemi")) {
    sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc, joinType)
} 
else {
     stop("joinType must be one of the following types: ",
             "'inner', 'outer', 'left_outer', 'right_outer', 'leftsemi'")
}

This fixed the issue, but I'm not sure if this solution breaks hive compatibility or causes other issues, but I can submit a pull request to change this

Issue Links

• links to: [Github] Pull Request #9029 (mfliu)