Doctrine supports sequences for generating record identifiers. Sequences are a way of offering unique IDs for data rows. If you do most of your work with e.g. MySQL, think of sequences as another way of doing AUTO_INCREMENT.
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Doctrine knows how to do sequence generation in the background so you don't have to worry about calling database specific queries - Doctrine does it for you, all you need to do
is define a column as a sequence column and optionally provide the name of the sequence table and the id column name of the sequence table.
Doctrine uses column named id as the sequence generator column of the sequence table. If you wish to change this globally (for all connections and all tables)