How can I create an External Catalog Table in Apache Flink

问题

I tried to create and ExternalCatalog to use in Apache Flink Table. I created and added to the Flink table environment (here the official documentation). For some reason, the only external table present in the 'catalog', it is not found during the scan. What I missed in the code above?

  val catalogName = s"externalCatalog$fileNumber"
  val ec: ExternalCatalog = getExternalCatalog(catalogName, 1, tableEnv)
  tableEnv.registerExternalCatalog(catalogName, ec)
  val s1: Table = tableEnv.scan("S_EXT")

  def getExternalCatalog(catalogName: String, fileNumber: Int, tableEnv: BatchTableEnvironment): ExternalCatalog = {
    val cat = new InMemoryExternalCatalog(catalogName)
    // external Catalog table
    val externalCatalogTableS = getExternalCatalogTable("S")
    // add external Catalog table
    cat.createTable("S_EXT", externalCatalogTableS, ignoreIfExists = false)
    cat
  }

  private def getExternalCatalogTable(fileName: String): ExternalCatalogTable = {
    // connector descriptor
    val connectorDescriptor = new FileSystem()
    connectorDescriptor.path(getFilePath(fileNumber, fileName))
    // format
    val fd = new Csv()
    fd.field("X", Types.STRING)
    fd.field("Y", Types.STRING)
    fd.fieldDelimiter(",")
    // statistic
    val statistics = new Statistics()
    statistics.rowCount(0)
    // metadata
    val md = new Metadata()
    ExternalCatalogTable.builder(connectorDescriptor)
      .withFormat(fd)
      .withStatistics(statistics)
      .withMetadata(md)
      .asTableSource()
  }

The example above is part of this test file in git.

回答1:

This is probably a namespace issue. Tables in external catalogs are identified by a list of names of the catalog, (potentially schemas,) and finally the table name.

In your example, the following should work:

val s1: Table = tableEnv.scan("externalCatalog1", "S_EXT")

You can have a look at the ExternalCatalogTest to see how external catalogs can be used.

来源：https://stackoverflow.com/questions/54278508/how-can-i-create-an-external-catalog-table-in-apache-flink

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