JDBC

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SparkR连接PostgreSQL数据库

成功安装了SparkR后，让我们来尝试下如何从PostgreSQL读取数据，

Sys.setenv(SPARK_HOME="/Users/steven/Applications/spark2")
.libPaths(c(file.path(Sys.getenv("SPARK_HOME"), "R", "lib"), .libPaths()))

library(SparkR)

d.pg="org.postgresql:postgresql:9.4.1209.jre7"
sc <- sparkR.session(master="local[2]",sparkPackages=c(d.pg))

url<-"jdbc:postgresql://localhost:5432/steven?user=postgres&password="
driver<-"org.postgresql.Driver"
df.pg <- read.jdbc(source="jdbc", url=url, tableName ="public.mtcars",driver=driver)

printSchema(df.pg)

collect(df.pg)
#createOrReplaceTempView(df.pg,"mtcars")
#sql("select * from mtcars")

sparkR.session.stop()

Sys.setenv(SPARK_HOME="/Users/steven/Applications/spark2")

.libPaths(c(file.path(Sys.getenv("SPARK_HOME"), "R", "lib"), .libPaths()))

library(SparkR)

d.pg="org.postgresql:postgresql:9.4.1209.jre7"

sc <- sparkR.session(master="local[2]",sparkPackages=c(d.pg))

url<-"jdbc:postgresql://localhost:5432/steven?user=postgres&password="

driver<-"org.postgresql.Driver"

df.pg <- read.jdbc(source="jdbc", url=url, tableName ="public.mtcars",driver=driver)

printSchema(df.pg)

collect(df.pg)

#createOrReplaceTempView(df.pg,"mtcars")

#sql("select * from mtcars")

sparkR.session.stop()

从代码可以看到，主要指定sparkPackages和read.jdbc命令，这段命令只要稍做修改，同样适用MySQL等支持JDBC连接的数据库。

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