It seems CREATE AGGREGATE was expanded in 9.6 to support parallelization of
aggregate functions using transitions, with the addition of serialfunc and
deserialfunc to the aggregate definitions.
https://www.postgresql.org/docs/10/static/sql-createaggregate.html
I was looking at the PostgreSQL 10 source code for some example usages of
this and was hoping that array_agg and string_agg would support the feature.
At a cursory glance, it seems they do not use this.
Examples I see that do support it are the average and standard deviation
functions.
Is there a reason for this or it just wasn't gotten to?
Thanks,
Regina
