tRecordMatching Standard properties

Schema and Edit schema

A schema is a row description, it defines the number of fields to be processed and passed on to the next component. The schema is either Built-in or stored remotely in the Repository.

Built-in: You create and store the schema locally for this component only. Related topic: see Talend Studio User Guide.

Repository: You have already created and stored the schema in the Repository. You can reuse it in other projects and Job designs. Related topic: see Talend Studio User Guide.

Replace output column with lookup column if matches or possible matches

Select this check box to replace the output column with the lookup column in case of match or possible match values.

Once this check box is selected, the Columns Mapping table appears.

Columns Mapping

Complete this table to define the output columns to be replaced and the corresponding substitute lookup columns. The column to be complete are:

- Output Column: select the column of interest from the drop-down list. On this list, two columns MATCHING_WEIGHT and MATCHING_DISTANCES, are defined by default; the other columns are available only when you have defined them in the schema editor of this component. For further information about these two default columns, see Matching entries using the Q-grams and Levenshtein algorithms;

- Lookup Column: select the column of interest from the drop-down list. This list is available when a lookup link has been defined to provide the corresponding lookup columns to this component.

Click the import icon to select a match rule from the Studio repository.

When you click the import icon, a Match Rule Selector wizard is opened to help you import match rules from the Studio repository and use them in your Job.

You can import rules created with the VSR algorithm. The T-Swoosh algorithm does not work with this component. For further information about importing VSR rules, see Importing match rules from the studio repository

Input Key Attribute

Select the column(s) from the main flow that needs to be checked against the reference (lookup) key column.

Lookup Key Attribute

Select the lookup key columns that you will use as a reference against which to compare the columns from the input flow.

Matching Function

Select the relevant matching algorithm from the list:

Exact Match: matches each processed entry to all possible reference entries with exactly the same value.

Levenshtein: Based on the edit distance theory. It calculates the number of insertion, deletion or substitution required for an entry to match the reference entry.

Metaphone: Based on a phonetic algorithm for indexing entries by their pronunciation. It first loads the phonetics of all entries of the lookup reference and checks all entries of the main flow against the entries of the reference flow.

Double Metaphone: a new version of the Metaphone phonetic algorithm, that produces more accurate results than the original algorithm. It can return both a primary and a secondary code for a string. This accounts for some ambiguous cases as well as for multiple variants of surnames with common ancestry.

Exact - ignore case: matches each processed entry to all possible reference entries with exactly the same value while ignoring the value case.

Soundex: matches processed entries according to a standard English phonetic algorithm.

Soundex FR: matches processed entries according to a standard French phonetic algorithm.

Jaro: matches processed entries according to spelling deviations.

q-grams: matches processed entries by dividing strings into letter blocks of length q in order to create a number of q length grams. The matching result is given as the number of q-gram matches over possible q-grams.

Hamming: calculates the minimum number of substitutions required to transform one string into another string having the same length. For example, the Hamming distance between "masking" and "pairing" is 3.

custom...: enables you to load an external matching algorithm from a Java library. The Custom Matcher column alongside is activated when you selected this option.

For further information about how to load an external Java library, see tLibraryLoad.

Custom Matcher

Type in the path pointing to the custom class (external matching algorithm) you need to use. This path is defined by yourself in the library file (.jar file) which you can import by using the tLibraryLoad component.

For further information, see Creating a custom matching algorithm.

Tokenized measure

Tokenization is the concept of splitting a string into words. Select the method to use to compute a tokenized measure for the selected algorithm:

NO: no tokenization method is used on the string. With this option, "John Doe" and "Jon Doe" should match.

Same place: splits the two strings by words to two lists, list1 and list2. Associates each element from list1 with the element which has the same position in list2. Using this method, "She is red and he is pink" and "Catherine is red and he is pink" should match.

Same order: splits the two strings by words to two lists, list1 and list2 and assumes that list1 is shorter than list2. Tries to associates the elements from list1 with the elements in list2 taken in the same order. Using this method, "John Doe" and "John B. Doe" match.

This method should be used only with strings which has a few words, otherwise the number of possible combinations can be large.

Any order: splits the two strings by words to two lists, list1 and list2 and assumes that list1 is shorter than list2. Tries to assign each word of list1 to a word of list2, in order to have the highest global similarity (with respect to the used similarity).

Using this method, "John Doe" and "Doe John" match.

Weight

Set a numerical weight for each attribute (column) of the key definition. The values can be anything >= 0.

Handle Null

Handle Null

To handle null values, select from the list the null operator you want to use on the column:

Null Match Null: a Null attribute only matches another Null attribute.

Null Match None: a Null attribute never matches another attribute.

Null Match All: a Null attribute matches any other value of an attribute.

For example, if we have two columns, name and firstname where the name is never null, but the first name can be null.

If we have two records:

"Doe", "John"

"Doe", ""

Depending on the operator you choose, these two records may or may not match:

Null Match Null: they do not match.

Null Match None: they do not match.

Null Match All: they match.

And for the records:

"Doe", ""

"Doe", ""

Null Match Null: they match.

Null Match None: they do not match.

Null Match All: they match.

Input Column

If required, select the column(s) from the input flow according to which you want to partition the processed data in blocks, this is usually referred to as "blocking".

Blocking reduces the number of pairs of records that needs to be examined. In blocking, input data is partitioned into exhaustive blocks designed to increase the proportion of matches observed while decreasing the number of pairs to compare. Comparisons are restricted to record pairs within each block.

Using blocking column(s) is very useful when you are processing very big data.

Matching Algorithm

Select an algorithm from the list. Only one algorithm is available for the time being

Simple VSR: This algorithm is based on a Vector Space Retrieval method that specifies how two records may match.

For further information about how to import rules based on the VSR algorithm, see Importing match rules from the studio repository.

Possible match interval

Enter a minimum and a maximum values:

minimum: set the minimum record distance allowed to match the reference (0 <= minimum). maximum: set the maximum distance allowed to match the reference (maximum <=1).

For example, if you set 0.5 as the minimum value and 0.9 as the maximum value, the scores equal or higher than 0.9 indicate match, the scores between 0.5 excluded and 0.9 excluded indicate possible match and the other scores indicate non match.

Store on disk

Select this check box if you want to store processed data blocks on the disk to maximize system performance.

tStatCatcher Statistics

Select this check box to collect log data at the component level.

Global Variables

NB_MATCH_LINE: the number of rows matching the comparison algorithm. This is an After variable and it returns an integer.

NB_POSSIBLE_MATCH_LINE: the number of rows possibly matching the comparison algorithm. This is an After variable and it returns an integer.

NB_NONE_MATCH_LINE: the number of rows not matching the comparison algorithm. This is an After variable and it returns an integer.

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage rule

This component is not startable and it requires two input components and one or more output components.