Re: Parallel Query

Some aspects of the new feature are explained in sparingly words only.
Maybe, they will not get clear for anybody and need some more explanations.
> 1: What part of the system is parallelized by use of additional
> processes? Is it the I/O activity, or RAM access, or net activity, or
> anything else? The question gets clear if one reads the complete
> chapter. But it may be better to say some words about the basic idea
> as a very first statement, eg: "In order to reduce the elapsed time of
> a query PostgreSQL can create query plans which distribute the query
> execution across multiple concurrent running processes. Each one use
> its own CPU and deals with a different part of the shared buffers. All
> other components of PostgreSQL like disc access or replication are not
> directly involved. The feature is known as parallel query. ..."
>
> 2: In chapter 15.1 there is an example which says: "Workers Planned:
> 2". The fact that 3 processes will execute this part of the query is
> mentioned at the bottom of the chapter. My feeling is, that the number
> "3" shall be expressed more clearly and near to the given example.
> And: the last paragraph of 15.1 uses the two terms "leader" and
> "gather nodes". Are they equivalent terms or is there any difference?
>
> 3: In chapter 15.3: Do we miss the word "be" in the phrase "it must
> (be) constructed so that ..."?
>
> Kind regards, Jürgen Purtz
>

Please find my suggestions for topics 1 and 2 in the attached file -
topic 3 is already patched.

Kind regards, Jürgen Purtz