[postmodern-devel] Postgres transaction warnings and save-dao

[Peter Stiernström]

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Hi all,

I'm using postmodern with great success but I keep seeing these two
warnings in my log:

 - "Postgres warning: there is no transaction in progress"
 - "Warning while processing connection: Postgres warning: there is
already a transaction in progress"

As far as I can tell these are merely warnings but they're filling up my
logs so I had a look at what was causing it and I found that save-dao
has a (with-transaction () ...) wrapping an insert-dao and I was calling
save-dao from within my own transaction block.

Now if just remove the with-transaction from save-dao an duplicate key
violation will ruin the outer transaction by just aborting it
(regardless of the error handling code. However if I add  a savepoint
just before trying insert-dao and in the error handling code use
rollback-savepoint to restore to this savepoint I can make the warnings
go away.

The problem now being that save-dao expects to be called within a
with-transaction form. So I was wondering if there is some way to tell
if we are within a transaction (e.g. within-transaction-p)? Then I would
be able to make a modification that handles both cases.

It might then look something like this:

(defun save-dao (dao)
  (if (within-transaction-p)
    (with-savepoint save-dao
      (handler-case (progn (insert-dao dao) t)
        (cl-postgres-error:unique-violation ()
          (rollback-savepoint save-dao)
          (update-dao dao)
          nil))))
     (handler-case (with-transaction () (insert-dao dao) t)
        (cl-postgres-error:unique-violation ()
          (update-dao dao)
          nil)))
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