flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-4686) Add possibility to get column names
Date Wed, 28 Sep 2016 14:40:20 GMT

    [ https://issues.apache.org/jira/browse/FLINK-4686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15529854#comment-15529854
] 

ASF GitHub Bot commented on FLINK-4686:
---------------------------------------

Github user twalthr commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2553#discussion_r80931476
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/Schema.scala
---
    @@ -0,0 +1,89 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.flink.api.table
    +
    +import org.apache.flink.api.common.typeinfo.TypeInformation
    +
    +/**
    +  * A Schema represents a Table's structure
    +  */
    +class Schema(
    +  val columnNames: Array[String],
    +  val columnTypes: Array[TypeInformation[_]]) {
    +
    +  if (columnNames.length != columnTypes.length) {
    +    throw new TableException(
    +      "Number of column indexes and column names must be equal.")
    +  }
    +
    +  // check uniqueness of field names
    +  if (columnNames.toSet.size != columnTypes.length) {
    +    throw new TableException(
    +      "Table column names must be unique.")
    +  }
    +
    +  val columnNameToIndex: Map[String, Int] = columnNames.zipWithIndex.toMap
    +
    +  /**
    +    * Returns all type informations as an array
    +    */
    +  def getTypes: Array[TypeInformation[_]] = columnTypes
    +
    +  /**
    +    * Returns the specified type information for the given column index
    + *
    +    * @param columnIndex the index of the field
    +    */
    +  def getType(columnIndex: Int): TypeInformation[_] = columnTypes(columnIndex)
    --- End diff --
    
    No index check here.


> Add possibility to get column names
> -----------------------------------
>
>                 Key: FLINK-4686
>                 URL: https://issues.apache.org/jira/browse/FLINK-4686
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: Timo Walther
>            Assignee: Jark Wu
>              Labels: starter
>
> For debugging and maybe for visualization in future (e.g. in a shell) it would be good
to have the possibilty to get the names of {{Table}} columns. At the moment the user has no
idea how the table columns are named; if they need to be matched with POJO fields for example.
> My suggestion:
> {code}
> Schema s = table.schema();
> TypeInformation<?> type = s.getType(1);
> TypeInformation<?> type = s.getType("col");
> String s = s.getColumnName(1);
> String[] s = s.getColumnNames();
> {code}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message