Tom Lane writes:
> The reason it works in read-committed mode is that the second guy to
> arrive at the row will observe that the row has an update in progress;
> will block waiting for the previous updater to commit or abort; and if
> commit, will use the updated version of the row as the starting point
> for his update. (This is what the EvalPlanQual ugliness in the executor
> is all about.)
Isn't that a violation of the principle that transactions in read
committed mode will look at the data that was committed *before* the
statement had begun?
--
Peter Eisentraut peter_e(at)gmx(dot)net