Project: Flink (App Definition and Development / Streaming & Messaging)
File: csv.md

title: CSV weight: 2 type: docs aliases: /dev/table/connectors/formats/csv.html <!-- 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. --> {{< label "Format: Serialization Schema" >}} {{< label "Format: Deserialization Schema" >}} The format allows to read and write CSV data based on an CSV schema. Currently, the CSV schema is derived from table schema. Dependencies {{< sqldownloadtable "csv" >}} How to create a table with CSV format Here is an example to create a table using Kafka connector and CSV format. ```sql CREATE TABLE user_behavior ( user_id BIGINT, item_id BIGINT, category_id BIGINT, behavior STRING, ts TIMESTAMP(3) ) WITH ( 'connector' = 'kafka', 'topic' = 'user_behavior', 'properties.bootstrap.servers' = 'localhost:9092', 'properties.group.id' = 'testGroup', 'format' = 'csv', 'csv.ignore-parse-errors' = 'true', 'csv.allow-comments' = 'true' ) ``` Format Options <table class="table table-bordered"> <thead> <tr> <th class="text-left" style="width: 25%">Option</th> <th class="text-center" style="width: 8%">Required</th> <th class="text-center" style="width: 8%">Forwarded</th> <th class="text-center" style="width: 7%">Default</th> <th class="text-center" style="width: 10%">Type</th> <th class="text-center" style="width: 42%">Description</th> </tr> </thead> <tbody> <tr> <td><h5>format</h5></td> <td>required</td> <td>no</td> <td style="word-wrap: break-word;">(none)</td> <td>String</td> <td>Specify what format to use, here should be <code>'csv'</code>.</td> </tr> <tr> <td><h5>csv.field-delimiter</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;"><code>,</code></td> <td>String</td> <td>Field delimiter character (<code>','</code> by default), must be single character. You can use backslash to specify special characters, e.g. <code>'\t'</code> represents the tab character. You can also use unicode to specify them in plain SQL, e.g. <code>'csv.field-delimiter' = U&'\0001'</code> represents the <code>0x01</code> character. </td> </tr> <tr> <td><h5>csv.disable-quote-character</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;">false</td> <td>Boolean</td> <td>Disabled quote character for enclosing field values (false by default). If true, option

can not be set.</td> </tr> <tr> <td><h5>csv.quote-character</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;"><code>"</code></td> <td>String</td> <td>Quote character for enclosing field values (<code>"</code> by default).</td> </tr> <tr> <td><h5>csv.allow-comments</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;">false</td> <td>Boolean</td> <td>Ignore comment lines that start with <code>'#'</code> (disabled by default). If enabled, make sure to also ignore parse errors to allow empty rows.</td> </tr> <tr> <td><h5>csv.ignore-parse-errors</h5></td> <td>optional</td> <td>no</td> <td style="word-wrap: break-word;">false</td> <td>Boolean</td> <td>Skip fields and rows with parse errors instead of failing. Fields are set to null in case of errors.</td> </tr> <tr> <td><h5>csv.array-element-delimiter</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;"><code>;</code></td> <td>String</td> <td>Array element delimiter string for separating array and row element values (<code>';'</code> by default).</td> </tr> <tr> <td><h5>csv.escape-character</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;">(none)</td> <td>String</td> <td>Escape character for escaping values (disabled by default).</td> </tr> <tr> <td><h5>csv.null-literal</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;">(none)</td> <td>String</td> <td>Null literal string that is interpreted as a null value (disabled by default).</td> </tr> <tr> <td><h5>csv.write-bigdecimal-in-scientific-notation</h5></td> <td>optional</td> <td>yes</td> <td style="word-wrap: break-word;">true</td> <td>Boolean</td> <td>Enables representation of BigDecimal data type in scientific notation (default is true). For example, 100000 is encoded as 1E+5 by default, and will be written as 100000 if set this option to false. Note: Only when the value is not 0 and a multiple of 10 is converted to scientific notation.</td> </tr> </tbody> </table> Data Type Mapping Currently, the CSV schema is always derived from table schema. Explicitly defining an CSV schema is not supported yet. Flink CSV format uses to parse and generate CSV string. The following table lists the type mapping from Flink type to CSV type. <table class="table table-bordered"> <thead> <tr> <th class="text-left">Flink SQL type</th> <th class="text-left">CSV type</th> </tr> </thead> <tbody> <tr> <td><code>CHAR / VARCHAR / STRING</code></td> <td><code>string</code></td> </tr> <tr> <td><code>BOOLEAN</code></td> <td><code>boolean</code></td> </tr> <tr> <td><code>BINARY / VARBINARY</code></td> <td><code>string with encoding: base64</code></td> </tr> <tr> <td><code>DECIMAL</code></td> <td><code>number</code></td> </tr> <tr> <td><code>TINYINT</code></td> <td><code>number</code></td> </tr> <tr> <td><code>SMALLINT</code></td> <td><code>number</code></td> </tr> <tr> <td><code>INT</code></td> <td><code>number</code></td> </tr> <tr> <td><code>BIGINT</code></td> <td><code>number</code></td> </tr> <tr> <td><code>FLOAT</code></td> <td><code>number</code></td> </tr> <tr> <td><code>DOUBLE</code></td> <td><code>number</code></td> </tr> <tr> <td><code>DATE</code></td> <td><code>string with format: date</code></td> </tr> <tr> <td><code>TIME</code></td> <td><code>string with format: time</code></td> </tr> <tr> <td><code>TIMESTAMP</code></td> <td><code>string with format: date-time</code></td> </tr> <tr> <td><code>INTERVAL</code></td> <td><code>number</code></td> </tr> <tr> <td><code>ARRAY</code></td> <td><code>array</code></td> </tr> <tr> <td><code>ROW</code></td> <td><code>object</code></td> </tr> </tbody> </table>