Page "InterBase" Paragraph 9
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In InterBase, readers do not block writers.
Instead, each record in the database can exist in more than one version.
For instance, when Bob and Jane read the accounts they would both get " version 1 ", reading 1000 dollars.
When Bob then changes the account to make his withdrawal the data is not overwritten, but instead a new " version 2 " will be created with 500 dollars.
Jane's attempt to make her 800 dollar withdrawal will notice that there is a new version 2, and her attempt to make a withdrawal will fail.
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