Computer Genealogy Programs - How Do They Work?

Author: Robert W. Penry @ 2021

Every genealogy program has a database.  It is a file of every individual that you enter in your program. Whenever you enter an individual, the record is created. A record is a collection of information about an individual. 
Within a record are pieces of information.  Each type of information is a field in the record.  The same fields are in every record.  But  the information in the field differs from individual to individual.
The following is an example of three records – with just a few fields.  Actually the number of fields in a genealogy program record are well over a hundred.


NAME: Bodine, John Thomas


DOB: 11Mar1821

POB: Marion, Marion, Ohio, USA

DOM: 05NOV1845

POM: Franklin, Franklin, Ohio, USA

DOD: 14Dec1862

POD: Kinston, Lenoir, North Carolina, CSA


NAME: Clampett, Ellie Mae


DOB: 05Feb2001

POB: Hunnewell, Greenup, Kentucky, USA

DOM: 25Dec2019

POM: Las Vegas, Clark, Nevada, USA




NAME:, Drysdale


DOB:, , 2022

POB:, , England, British Isles



DOD:, Apr2022

POD:, , , Atlantic Ocean

As you view the sample records, you notice that all records in the genealogy database have the same fields.  You should also notice that if a particular piece of information doesn’t exist, then the field is blank.  Is Ellie Mae living? She has no Date of Death (DOD).  She is either still alive, or if she died, we don’t know when or where.  


The individuals in records one and three are certainly deceased.  Record three obviously was never married since he was less than five months old at death. 
Did you notice that John Bodine died in the Confederate States of America?  By the way, the Battle of Kinston was fought on 14th of December, 1862.  Does this mean that we should examine some military records?


Did you notice the place markers in fields? The comma (,) marks show where missing information in the field would appear.  For record three, (, , 2022) the place markers indicate that this is a valid record. As a programmer, I know that this field is right justified. This means that typing 2022 in the field, slides the data to the right, leaving the day and month area of the field blank.  The program does this automatically as part of its edits.  


Note that all fields have a field size.  The DOB field size is 9 digits dd/mmm/yyyy.  Even though the name and date fields have different lengths of information, there is a maximum field size for them.  Actually the field size limit for all name and location fields is 255 characters. 


Are these the field size limits for these fields in GEDCOM?  Absolutely!  In order to import/export GEDCOM.  All genealogy programs have field lengths that match GEDCOM field lengths.  
Source: SlidePlayer
Source: FileMaker Pro
How does the computer identify each record? It can’t use the name because the same name can be used on many records.  How many William Smith’s are the world?  In medieval times, here were no surnames. There were thousands of persons named Edward or Mary.
There are two very important fields that I didn’t include in the sample records above.  
When you start entering a new record, the genealogy program assigns a unique number to the record.  These numbers are assigned sequentially. This field is the Record Indicator Number or RIN.  The very first record you entered was given RIN 1, the next record RIN 2 and so on.  My own file is  now at RIN 85852. Does this match the number of records or people in my file?  Almost.  If a record is deleted, the number is not reused.
The database is the sum total of records in the file. A programmer of one genealogy program told me that the program would run out of room for more records long before it ran out of RIN’s.
The second critical field is the Marriage Record Identification Number, The MRIN.  Every time a marriage is entered, a MRIN is assigned. An individual’s record contains a MRIN pointer linking the individual to his parent’s marriage. 
An individual has only one RIN, but can have Multiple MRIN pointers.  This allows for step-parents, adoption parents and multiple marriages
I have two MRIN pointers.  One is to my birth parents.  My mother divorced by birth father, remarried and my step-father adopted me.  Thus I have two fathers.
The combination of RIN’s and MRIN’s build families in the genealogy program making computer-based genealogy possible.
In FamilySearch, instead of a RIN, a alpha/numeric number call the FamilySearch ID is used.  My Great-Grandfather in FamilySearch has been assigned the ID of KPQR-54S.  How many possible combinations can be made with this ID number? (10³⁶)  it will never run out of ID numbers. Since the beginning of time, approximately 20 billion people have existed on the Earth.  FamilySearch can accommodate many, many more.  
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