Re: How the Planner in PGStrom differs from PostgreSQL?

On 11/14/2016 9:25 PM, Mark Anns wrote:
> I am just curious about this planning factors in GPU.
>
> There can be more than one appropriate paths in query plan tree. How the
> decision for particular path has been made considering those planning
> factors?

the postgresql planner considers a number of alternate execution plans,
assigns each step of each plan a estimated cost and for each plan sums
up those costs, the plan with the lowest cost wins.

the documentation on EXPLAIN [1] [2] goes into the basics of planning.
Chapter 67 [3] goes into some more detail.

[1] https://www.postgresql.org/docs/current/static/using-explain.html
[2] https://www.postgresql.org/docs/current/static/planner-stats.html
[3]
https://www.postgresql.org/docs/current/static/row-estimation-examples.html

--
john r pierce, recycling bits in santa cruz