Help Center/ Cloud Data Migration/ User Guide/ Creating a Job in a CDM Cluster/ Configuring CDM Job Field Mapping
Updated on 2024-10-24 GMT+08:00
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Configuring CDM Job Field Mapping

Scenario

  • After the job parameters are configured, you can configure field mapping. You can click on the Map Field page to customize new fields or click in the Operation column to create a field converter.
  • If files are migrated between FTP, SFTP, OBS, and HDFS and the migration source's File Format is set to Binary, files will be directly transferred, free from field mapping.
  • In other scenarios, CDM automatically maps fields of the source table and the destination table. You need to check whether the mapping and time format are correct. For example, check whether the source field type can be converted into the destination field type.
  • In the auto table creation scenario, you need to add fields to the destination table in advance, and add the fields to the field mapping..

Constraints

  • If Use SQL Statement is set to Yes in the source job configuration, converters cannot be created.
  • On the Map Field tab page, if CDM fails to obtain all columns by obtaining sample values (for example, when data is exported from HBase, CloudTable, or MongoDB, there is a high probability that CDM failed to obtain all columns), you can click and select Add a new field to add new fields to ensure that the data imported to the migration destination is complete.
  • When a relational database, Hive, DLI, or MRS Hudi is used as the migration source, sample values cannot be obtained.
  • When SQLServer is the destination, fields of the timestamp type cannot be written. You must change their type (for example, to datetime) so that they can be written.
  • Column names are displayed when the source of the migration job is OBS, CSV files are to be migrated, and parameter Extract first row as columns is set to Yes.
  • Field mapping is not involved when the binary format is used to migrate files to files.
  • In the automatic table creation scenario, you need to manually add fields to the destination table in advance and then add fields to the field mapping.
  • After a field is added, its sample value is not displayed on the console. This does not affect the field value transmission. CDM directly writes the field value to the destination end.
  • If the field mapping is incorrect, you can adjust the field mapping by dragging fields or clicking to map fields in batches.
  • If the data is imported to DWS, you need to select the distribution columns in the destination fields. You are advised to select the distribution columns according to the following principles:
    1. Use the primary key as the distribution column.
    2. If multiple data segments are combined as primary keys, specify all primary keys as the distribution column.
    3. In the scenario where no primary key is available, if no distribution column is selected, DWS uses the first column as the distribution column by default. As a result, data skew risks exist.
  • If a source field type is not supported, convert the field type to a type supported by CDM by referring to Converting Unsupported Data Types.

Adding a Field

You can click on the Map Field page and select Add to customize a new field. This field is usually used to mark the database source to ensure the integrity of the data imported to the migration destination.
Figure 1 Field mapping
Currently, the following field types are supported:
  • Constant Parameter

    Constant parameters are fixed parameters and do not need to be reconfigured. For example, lable = friends is used to identify a constant value.

  • Variables

    You can use variables such as time macros, table name macros, and version macros to mark database source information. The variable syntax is ${variable}, where variable indicates a variable. For example, input_time = ${timestamp()} indicates the timestamp of the current time.

  • Expression

    You can use the expression language to dynamically generate parameter values based on the running environment. The expression syntax is #{expr}, where expr indicates an expression. For example, time = #{DateUtil.now()} is used to identify the current date string.

Creating a Converter

CDM supports field conversion. Click and then click Create Converter.
Figure 2 Creating a converter

CDM can convert fields during migration. Currently, the following field converters are supported:

  • Anonymization
    This converter is used to hide key information about the character string. For example, if you want to convert 12345678910 to 123****8910, configure the parameters as follows:
    • Set Reserve Start Length to 3.
    • Set Reserve End Length to 4.
    • Set Replace Character to *.
  • Trim

    This converter is used to automatically delete the spaces before and after a string. No parameters need to be configured.

  • Reverse string

    This converter is used to automatically reverse a string. For example, reverse ABC into CBA. No parameters need to be configured.

  • Replace string

    This converter is used to replace a character string. You need to configure the object to be replaced and the new value.

  • Remove line break

    This converter is used to delete the newline characters, such as \n, \r, and \r\n from the field.

  • Expression conversion

    During data conversion, if the content to be replaced contains a special character, use a backslash (\) to escape the special character to a common one.

    • The expression supports the following environment variables:
      • value: indicates the current field value.
      • row: indicates the current row, which is an array type.
    • The expression supports the following Utils:
      1. If the field is of the string type, convert all character strings into lowercase letters, for example, convert aBC to abc.

        Expression: StringUtils.lowerCase(value)

      2. Convert all character strings of the current field to uppercase letters.

        Expression: StringUtils.upperCase(value)

      3. Convert the format of the first date field from 2018-01-05 15:15:05 to 20180105.

        Expression: DateUtils.format(DateUtils.parseDate(row[0],"yyyy-MM-dd HH:mm:ss"),"yyyyMMdd")

      4. Convert a timestamp to a date string in yyyy-MM-dd hh:mm:ss format, for example, convert 1701312046588 to 2023-11-30 10:40:46.

        Expression: DateUtils.format(NumberUtils.toLong(value),"yyyy-MM-dd HH:mm:ss")

      5. Convert a date string in the yyyy-MM-dd hh:mm:ss format to a timestamp.

        Expression: DateUtils.getTime(DateUtils.parseDate(value,"yyyy-MM-dd hh:mm:ss"))

      6. If the field value is a date string in yyyy-MM-dd format, extract the year from the field value, for example, extract 2017 from 2017-12-01.

        Expression: StringUtils.substringBefore(value,"-")

      7. If the field value is of the numeric type, convert the value to a new value which is two times greater than the original value:

        Expression: value*2

      8. Convert the field value true to Y and other field values to N.

        Expression: value=="true"?"Y":"N"

      9. If the field value is of the string type and is left empty, convert it to Default. Otherwise, the field value will not be converted.

        Expression: empty value? "Default":value

      10. Convert date format 2018/01/05 15:15:05 to 2018-01-05 15:15:05:

        Expression: DateUtils.format(DateUtils.parseDate(value,"yyyy/MM/dd HH:mm:ss"),"yyyy-MM-dd HH:mm:ss")

      11. Obtain a 36-bit universally unique identifier (UUID):

        Expression: CommonUtils.randomUUID()

      12. If the field is of the string type, capitalize the first letter, for example, convert cat to Cat.

        Expression: StringUtils.capitalize(value)

      13. If the field is of the string type, convert the first letter to a lowercase letter, for example, convert Cat to cat.

        Expression: StringUtils.uncapitalize(value)

      14. If the field is of the string type, use a space to fill in the character string to the specified length and center the character string. If the length of the character string is not shorter than the specified length, do not convert the character string. For example, convert ab to meet the specified length 4.

        Expression: StringUtils.center(value,4)

      15. Delete a newline (including \n, \r, and \r\n) at the end of a character string. For example, convert abc\r\n\r\n to abc\r\n.

        Expression: StringUtils.chomp(value)

      16. If the string contains the specified string, true is returned; otherwise, false is returned. For example, abc contains a so that true is returned.

        Expression: StringUtils.contains(value,"a")

      17. If the string contains any character of the specified string, true is returned; otherwise, false is returned. For example, zzabyycdxx contains either z or a so that true is returned.

        Expression: StringUtils.containsAny(value,"za")

      18. If the string does not contain any one of the specified characters, true is returned. If any specified character is contained, false is returned. For example, abz contains one character of xyz so that false is returned.

        Expression: StringUtils.containsNone(value,"xyz")

      19. If the string contains only the specified characters, true is returned. If any other character is contained, false is returned. For example, abab contains only characters among abc so that true is returned.

        Expression: StringUtils.containsOnly(value,"abc")

      20. If the character string is empty or null, convert it to the specified character string. Otherwise, do not convert the character string. For example, convert the empty character string to null.

        Expression: StringUtils.defaultIfEmpty(value,null)

      21. If the string ends with the specified suffix (case sensitive), true is returned; otherwise, false is returned. For example, if the suffix of abcdef is not null, false is returned.

        Expression: StringUtils.endsWith(value,null)

      22. If the string is the same as the specified string (case sensitive), true is returned; otherwise, false is returned. For example, after strings abc and ABC are compared, false is returned.

        Expression: StringUtils.equals(value,"ABC")

      23. Obtain the first index of the specified character string in a character string. If no index is found, -1 is returned. For example, the first index of ab in aabaabaa is 1.

        Expression: StringUtils.indexOf(value,"ab")

      24. Obtain the last index of the specified character string in a character string. If no index is found, -1 is returned. For example, the last index of k in aFkyk is 4.

        Expression: StringUtils.lastIndexOf(value,"k")

      25. Obtain the first index of the specified character string from the position specified in the character string. If no index is found, -1 is returned. For example, the first index of b obtained after the index 3 of aabaabaa is 5.

        Expression: StringUtils.indexOf(value,"b",3)

      26. Obtain the first index of any specified character in a character string. If no index is found, -1 is returned. For example, the first index of z or a in zzabyycdxx. is 0.

        Expression: StringUtils.indexOfAny(value,"za")

      27. If the string contains any Unicode character, true is returned; otherwise, false is returned. For example, ab2c contains only non-Unicode characters so that false is returned.

        Expression: StringUtils.isAlpha(value)

      28. If the string contains only Unicode characters and digits, true is returned; otherwise, false is returned. For example, ab2c contains only Unicode characters and digits, so that true is returned.

        Expression: StringUtils.isAlphanumeric(value)

      29. If the string contains only Unicode characters, digits, and spaces, true is returned; otherwise, false is returned. For example, ab2c contains only Unicode characters and digits, so that true is returned.

        Expression: StringUtils.isAlphanumericSpace(value)

      30. If the string contains only Unicode characters and spaces, true is returned; otherwise, false is returned. For example, ab2c contains Unicode characters and digits so that false is returned.

        Expression: StringUtils.isAlphaSpace(value)

      31. If the string contains only printable ASCII characters, true is returned; otherwise, false is returned. For example, for !ab-c~, true is returned.

        Expression: StringUtils.isAsciiPrintable(value)

      32. If the string is empty or null, true is returned; otherwise, false is returned.

        Expression: StringUtils.isEmpty(value)

      33. If the string contains only Unicode digits, true is returned; otherwise, false is returned.

        Expression: StringUtils.isNumeric(value)

      34. Obtain the leftmost characters of the specified length. For example, obtain the leftmost two characters ab from abc.

        Expression: StringUtils.left(value,2)

      35. Obtain the rightmost characters of the specified length. For example, obtain the rightmost two characters bc from abc.

        Expression: StringUtils.right(value,2)

      36. Concatenate the specified character string to the left of the current character string and specify the length of the concatenated character string. If the length of the current character string is not shorter than the specified length, the character string will not be converted. For example, if yz is concatenated to the left of bat and the length must be 8 after concatenation, the character string is yzyzybat after conversion.

        Expression: StringUtils.leftPad(value,8,"yz")

      37. Concatenate the specified character string to the right of the current character string and specify the length of the concatenated character string. If the length of the current character string is not shorter than the specified length, the character string will not be converted. For example, if yz is concatenated to the right of bat and the length must be 8 after concatenation, the character string is batyzyzy after conversion.

        Expression: StringUtils.rightPad(value,8,"yz")

      38. If the field is of the string type, obtain the length of the current character string. If the character string is null, 0 is returned.

        Expression: StringUtils.length(value)

      39. If the field is of the string type, delete all the specified character strings from it. For example, delete ue from queued to obtain qd.

        Expression: StringUtils.remove(value,"ue")

      40. If the field is of the string type, remove the substring at the end of the field. If the specified substring is not at the end of the field, no conversion is performed. For example, remove .com at the end of www.domain.com.

        Expression: StringUtils.removeEnd(value,".com")

      41. If the field is of the string type, delete the substring at the beginning of the field. If the specified substring is not at the beginning of the field, no conversion is performed. For example, delete www. at the beginning of www.domain.com.

        Expression: StringUtils.removeStart(value,"www.")

      42. If the field is of the string type, replace all the specified character strings in the field. For example, replace a in aba with z to obtain zbz.

        Expression: StringUtils.replace(value,"a","z")

        If the content to be replaced contains a special character, the special character must be escaped to a common character. For example, if you want to delete \t from a string, use the following expression: StringUtils.replace(value,"\\t",""), which means escaping the backslash (\) again.

      43. If the field is of the string type, replace multiple characters in the character string at a time. For example, replace h in hello with j and o with y to obtain jelly.

        Expression: StringUtils.replaceChars(value,"ho","jy")

      44. If the string starts with the specified prefix (case sensitive), true is returned; otherwise, false is returned. For example, abcdef starts with abc, so that true is returned.

        Expression: StringUtils.startsWith(value,"abc")

      45. If the field is of the string type, delete all the specified characters at the beginning and end of the field. the field. For example, delete all x, y, z, and b from abcyx to obtain abc.

        Expression: StringUtils.strip(value,"xyzb")

      46. If the field is of the string type, delete all the specified characters at the end of the field, for example, delete the "abc" string at the end of the field.

        Expression: StringUtils.stripEnd(value,"abc")

      47. If the field is of the string type, delete all the specified characters at the beginning of the field, for example, delete all spaces at the beginning of the field.

        Expression: StringUtils.stripStart(value,null)

      48. If the field is of the string type, obtain the substring after the specified position (the index starts from 0, including the character at the specified position) of the character string. If the specified position is a negative number, calculate the position in the descending order. The first digit at the end is -1. For example, obtain the character whose index is 2 from abcde (that is, c) and the string after it, that is, cde.

        Expression: StringUtils.substring(value,2)

      49. If the field is of the string type, obtain the substring in a specified range (the index starts from 0, including the character at the start and excluding the character at the end). If the range is a negative number, calculate the position in the descending order. The first digit at the end is -1. For example, obtain the string between the second character (c) and fourth character (e) of abcde, that is, cd.

        Expression: StringUtils.substring(value,2,4)

      50. If the field is of the string type, obtain the substring after the first specified character. For example, obtain the substring after the first b in abcba, that is, cba.

        Expression: StringUtils.substringAfter(value,"b")

      51. If the field is of the string type, obtain the substring after the last specified character. For example, obtain the substring after the last b in abcba, that is, a.

        Expression: StringUtils.substringAfterLast(value,"b")

      52. If the field is of the string type, obtain the substring before the first specified character. For example, obtain the substring before the first b in abcba, that is, a.

        Expression: StringUtils.substringBefore(value,"b")

      53. If the field is of the string type, obtain the substring before the last specified character. For example, obtain the substring before the last b in abcba, that is, abc.

        Expression: StringUtils.substringBeforeLast(value,"b")

      54. If the field is of the string type, obtain the substring nested within the specified string. If no substring is found, null is returned. For example, obtain the substring between tag in tagabctag, that is, abc.

        Expression: StringUtils.substringBetween(value,"tag")

      55. If the field is of the string type, delete the control characters (char≤32) at both ends of the character string, for example, delete the spaces at both ends of the character string.

        Expression: StringUtils.trim(value)

      56. Convert the character string to a value of the byte type. If the conversion fails, 0 is returned.

        Expression: NumberUtils.toByte(value)

      57. Convert the character string to a value of the byte type. If the conversion fails, the specified value, for example, 1, is returned.

        Expression: NumberUtils.toByte(value,1)

      58. Convert the character string to a value of the double type. If the conversion fails, 0.0d is returned.

        Expression: NumberUtils.toDouble(value)

      59. Convert the character string to a value of the double type. If the conversion fails, the specified value, for example, 1.1d, is returned.

        Expression: NumberUtils.toDouble(value,1.1d)

      60. Convert the character string to a value of the float type. If the conversion fails, 0.0f is returned.

        Expression: NumberUtils.toFloat(value)

      61. Convert the character string to a value of the float type. If the conversion fails, the specified value, for example, 1.1f, is returned.

        Expression: NumberUtils.toFloat(value,1.1f)

      62. Convert the character string to a value of the int type. If the conversion fails, 0 is returned.

        Expression: NumberUtils.toInt(value)

      63. Convert the character string to a value of the int type. If the conversion fails, the specified value, for example, 1, is returned.

        Expression: NumberUtils.toInt(value,1)

      64. Convert the character string to a value of the long type. If the conversion fails, 0 is returned.

        Expression: NumberUtils.toLong(value)

      65. Convert the character string to a value of the long type. If the conversion fails, the specified value, for example, 1L, is returned.

        Expression: NumberUtils.toLong(value,1L)

      66. Convert the character string to a value of the short type. If the conversion fails, 0 is returned.

        Expression: NumberUtils.toShort(value)

      67. Convert the character string to a value of the short type. If the conversion fails, the specified value, for example, 1, is returned.

        Expression: NumberUtils.toShort(value,1)

      68. Convert the IP string to a value of the long type, for example, convert 10.78.124.0 to 172915712.

        Expression: CommonUtils.ipToLong(value)

      69. Read an IP address and physical address mapping file from the network, and download the mapping file to the map collection. url indicates the address for storing the IP mapping file, for example, http://10.114.205.45:21203/sqoop/IpList.csv.

        Expression: HttpsUtils.downloadMap("url")

      70. Cache the IP address and physical address mappings and specify a key for retrieval, for example, ipList.

        Expression: CommonUtils.setCache("ipList",HttpsUtils.downloadMap("url"))

      71. Obtain the cached IP address and physical address mappings.

        Expression: CommonUtils.getCache("ipList")

      72. Check whether the IP address and physical address mappings are cached.

        Expression: CommonUtils.cacheExists("ipList")

      73. Based on the specified offset type (month/day/hour/minute/second) and offset (positive number indicates increase and negative number indicates decrease), convert the time in the specified format to a new time, for example, add 8 hours to 2019-05-21 12:00:00.

        Expression: DateUtils.getCurrentTimeByZone("yyyy-MM-dd HH:mm:ss",value, "hour", 8)

      74. If the value is empty or null, "aaa" is returned. Otherwise, value is returned.

        Expression: StringUtils.defaultIfEmpty(value,"aaa")

Special Links

  • If the source link is a DLI link, and the destination link is a DWS link, fields of the tinyint type of the DLI link are mapped to fields of the smallint type of the DWS link.
  • If the source link is a Hudi link, and the destination link is a DWS link, fields of the Double type of the Hudi link are mapped to fields of the Float type of the DWS link.