Record matching rules are used when importing MARC records into Koha.

The rules that you set up here will be referenced with you Stage MARC Records for Import.

It is important to understand the difference between Match Points and Match Checks before adding new matching rules to Koha.

Match Points are the criteria that you enter that must be met in order for an incoming record to match an existing MARC record in your catalog. You can have multiple match points on an import rule each with its own score. An incoming record will be compared against your existing records (‘one record at a time’) and given a score for each match point. When the total score of the matchpoints matches or exceeds the threshold given for the matching rule, Koha assumes a good match and imports/overlays according your specifications in the import process. An area to watch out for here is the sum of the match points. Doublecheck that the matches you want will add up to a successful match.

Example:

Threshold of 1000

Match Point on 020$a 1000

Match Point on 022$a 1000

Match Point on 245$a 500

Match Point on 100$a 100

In the example above, a match on either the 020$a or the 022$a will result in a successful match. A match on 245$a title and 100$a author (and not on 020$a or 022$a) will only add up to 600 and not be a match. And a match on 020$a and 245$a will result in 1500 and while this is a successful match, the extra 500 point for the 245$a title match are superfluous. The incoming record successfully matched on the 020$a without the need for the 245$a match. However, if you assigned a score of 500 to the 100$a Match Point, a match on 245$a title and 100$a author will be considered a successful match (total of 1000) even if the 020$a is not a match.

Match Checks are not commonly used in import rules. However, they can serve a couple of purposes in matching records. First, match checks can be used as the matching criteria instead of the match points if your indexes are stale and out of date. The match checks go right for the data instead of relying on the data in the indexes. (If you fear your indexes are out of date, a rebuild of your indexes would be a great idea and solve that situation!) The other use for a Match Check is as a “double check” or “veto” of your matching rule. For example, if you have a matching rule as below:

Threshold of 1000

Match Point on 020$a 1000

Match Check on 245$a

Koha will first look at the 020$a tag/subfield to see if the incoming record matches an existing record. If it does, it will then move on to the Match Check and look directly at the 245$a value in the incoming data and compare it to the 245$a in the existing ‘matched’ record in your catalog. If the 245$a matches, Koha continues on as if a match was successful. If the 245$a does not match, then Koha concludes that the two records are not a match after all. The Match Checks can be a really useful tool in confirming true matches.

When looking to create matching rules for your authority records the following indexes will be of use:

4.7.2. Sample Bibliographic Record Matching Rule: Control Number

• Match threshold: 100

• Record type: Bibliographic

  Note

  If you'd like a rule to match on the 001 in authority records you will need the repeat all of these values and change just the record type to 'Authority record'

• Matchpoints (just the one):

• Search index: Control-number

• Score: 101

• Tag: 001

  Note

  this field is for the control number assigned by the organization creating, using, or distributing the record

• Subfields: a

• Offset: 0

• Length: 0

• Normalization rule: Control-number

• Required Match checks: none (remove the blank one)