Paul, * Paul Ramsey (pram...@cleverelephant.ca) wrote: > On Mon, Mar 28, 2016 at 9:45 AM, Stephen Frost <sfr...@snowman.net> wrote: > > Would you agree that it'd be helpful to have for making the st_union() > > work better in parallel? > > For our particular situation w/ ST_Union, yes, it would be ideal to be > able to run a worker-side combine function as well as the master-side > one. Although the cascaded union would be less effective spread out > over N nodes, doing it only once per worker, rather than every N > records would minimize the loss of effectiveness.
I chatted with Robert a bit about this and he had an interesting suggestion. I'm not sure that it would work for you, but the serialize/deserialize functions are used to transfer the results from the worker process to the main process. You could possibly do the per-worker finalize work in the serialize function to get the benefit of running that in parallel. You'll need to mark the aggtranstype as 'internal' to have the serialize/deserialize code called. Hopefully that's not too much of an issue. Thanks! Stephen
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