Re:MongoDB: How to Use the JSON Schema Validator
by rooam-dev on Tuesday August 21, 2018 @07:40AM
(#17808719)
If that's the case, then one less problem to deal with, however I remember it was a matter of several minutes.
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Re:MongoDB: How to Use the JSON Schema Validator
by anarazel on Tuesday August 21, 2018 @08:06AM
(#17808834)
That's only the case if you add a DEFAULT value for the new column. Up until the soon-to-be-released v11 that required updating existing rows. Without a default it's essentially just inserting a single row in a row into an internal catalog table (pg_attribute). With a default in v11, we basically just store the default for a new column out of line, and reference it when the row is read.
In either case a lock has to be acquired on the table, which means if there's a longrunning transaction, you can end up blocking for a while...