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
(https://dev.mysql.com/doc/x-devapi-userguide/en/understanding-automatic-document-ids.html)
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 …
Showing entries 1 to 1
Apr
21
2018
Showing entries 1 to 1