Table of Contents

PLP: Primary Keys §

In PLP, the primary keys are: 

  • OCLC number (taken from the 001 or 035$a with prefix '(OCoLC)' ) 
  • LCCN (taken from 010 $a) 
  • ISBN (taken from 020 $a) 
  • ISSN (taken from 022 $a) 
  • TITLE (taken from 245 $anphb), and 
  • SYSID (taken from the 035 $a with a user-specified prefix) 

We use the phrase 'match key' interchangeably with 'primary key'. 

A primary key, or match key, is the piece of data that is used to try to match each record in your file with one or more records in the database. It is very much the same idea as you would use when searching any library catalog. 

For each primary key, the following two 'limits' can be set: 

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Max Hits §

If a primary key query matches more than this number of DB records, and no other primary key succeeds in making a match, then the record is output to a 'TooManyHits' file.  

Max Hits can be set to any number from 0 to 99. 

If Max Hits is set to 0 then it is turned off–PLP will not check for Max Hits. 

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MaxFails §

If all DB records retrieved for the matching primary key fail the crosschecks, and if the number of crosschecks failed for each DB record is greater than or equal to the Max Fails setting, then the DB records are discarded and the result for that primary key result is changed to No hit (which will cause the record to go to No Match if no other primary keys Match or Fail) 

Max Fails can be set to any number from 2 to 20. 

If Max Fails is set to 0 then it is turned off–PLP will not check for Max Fails. 

Notes So, there are a few conditions that must be met in order for Max Fails to kick in.  

For example, if the library record matches three DB records on ISBN, and the crosscheck results are– 

DB 1: X260B, X300A, X300C, XDATE DB 2: X260B, X300A, X300C, XDATE, X250A DB 3: X260B, X300A, XDATE 

–If Max Fails is set to 4, then the record still goes to XCFails, because DB record 3 failed only 3 crosschecks, which is less than Max Fails number of crosschecks. 

But if, for the same library record, the TITLE search then runs and matches two DB records, with crosscheck results of– 

DB 1: X260B, X300A, X300C, XDATE DB 2: X260B, X300A, X300C, XDATE, X250A 

Then the record goes to NoMatch, because all DB records retrieved for the matching primary key failed the crosschecks, and the number of crosschecks failed for each is greater than or equal to the Max Fails setting. 

One last note: Max Hits trumps Max Fails. By this I mean that if both Max Hits and Max Fails become true when a library record is being matched, and no other options kick in, the record will always go to TooManyHits instead of NoMatch 

MaxHits takes precedence over MaxFails. 

plp/primary_keys/primary.txt · Last modified: 2013/04/27 09:09 (external edit)
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