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MySQL Document Store Document IDs.

Yesterday I was presenting on the MySQL Document Store and was asked if the _id fields created by the server as an InnoDB primary key is a UUID.  I knew that it was not a UUID but I had to hit the documentations ( to find out what the document ID really is -- a very interesting piece of information.
The Details If you are inserting a document lacking a _id key, the server generates a value. The _id is 32 bits of a unique prefix (4 bytes), a time stamp (8 bytes), and serial number (16 bytes). The prefix is assigned by the InnoDB Cluster to help ensure uniqueness across a cluster. The timestamp is the encoded startup time of the server.  The serial numbers uses the auto increment offset and auto increment increment server variables .  From the manual page:
This document ID format ensures …

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