[Evergreen-dev] Time to deprecate "authoritative" APIs?

[Bill Erickson]

Hi All,

I was recently reviewing some activity logs and found these top 5 API calls
(with counts) for last Thursday:

  46398 open-ils.pcrud.retrieve.au
  41363 open-ils.actor.get_barcodes
  33044 open-ils.pcrud.transaction.begin
  32591 open-ils.pcrud.transaction.rollback
  30549 open-ils.pcrud.search.atc

Way down the list I have:

  452 open-ils.pcrud.transaction.commit

If I take out the ~450 begin/commit pairs, which perform real work, I'm
left with ~65k begin + rollback API calls.  That's roughly 1 of every 10
API calls that hit our system.

Not only are there a lot of them, each results in a begin or rollback call
in the database.  The calls are fast and generally harmless on a per-call
basis, but they do make it to the database every time, so they're not
exactly trivial/superficial.

The begin/rollback pairs are the result of using "authoritative" data
retrieval -- calls that start a database transaction so the caller can be
sure any data retrieved comes from the primary database.  This is useful
when a) data must be up to date to avoid confusion/oddness in the UI and b)
the Evergreen system is running one or more pooled database replicas that
handle live read queries -- live replicas can occasionally lag behind with
replication and return very slightly older data than the primary database.

For sites like KCLS, where all live queries go to one primary database,
these API calls serve no purpose.  (We have replicas, but they are not part
of an active load-balanced pool.  They are used instead for reporting, bulk
data collection, debugging, and of course backups).

Since these begin + rollback pairs (and ".authoritative" APIs) serve no
purpose in our environment, I was considering creating a local patch to
disable them.  However, before I start patching locally, I'm curious if
there is a broader desire for deprecating authoritative APIs?  I suspect
they can be turned into NO-OP's with 2 or 3 well-placed lines of code.

Do many/any of you use live, read-only pooled database replicas?

I'd love to hear your thoughts/concerns/etc.

Thanks,

-b
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.evergreen-ils.org/pipermail/evergreen-dev/attachments/20230320/6d36455d/attachment.htm>