Uploaded image for project: 'Spark'
  1. Spark
  2. SPARK-24423

Add a new option `query` for JDBC sources

    XMLWordPrintableJSON

    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.3.0
    • Fix Version/s: 2.4.0
    • Component/s: SQL
    • Labels:
      None
    • Target Version/s:

      Description

      Currently, our JDBC connector provides the option `dbtable` for users to specify the to-be-loaded JDBC source table. 

       
       val jdbcDf = spark.read
         .format("jdbc")
         .option("*dbtable*", "dbName.tableName")
         .options(jdbcCredentials: Map)
         .load()
      

       
      Normally, users do not fetch the whole JDBC table due to the poor performance/throughput of JDBC. Thus, they normally just fetch a small set of tables. For advanced users, they can pass a subquery as the option.   

       
       val query = """ (select * from tableName limit 10) as tmp """
       val jdbcDf = spark.read
         .format("jdbc")
         .option("*dbtable*", query)
         .options(jdbcCredentials: Map)
         .load()
      

       
      However, this is straightforward to end users. We should simply allow users to specify the query by a new option `query`. We will handle the complexity for them. 

       
       val query = """select * from tableName limit 10"""
       val jdbcDf = spark.read
         .format("jdbc")
         .option("*{color:#ff0000}query{color}*", query)
         .options(jdbcCredentials: Map)
         .load()
      

       
      Users are not allowed to specify query and dbtable at the same time. 

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                dkbiswal Dilip Biswal
                Reporter:
                smilegator Xiao Li
              • Votes:
                0 Vote for this issue
                Watchers:
                5 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: