RE: Parallel Inserts in CREATE TABLE AS

> > I think it makes sense.
> >
> > And if the check about ' ins_cmd == xxx1 || ins_cmd == xxx2' may be
> > used in some places, How about define a generic function with some comment
> to mention the purpose.
> >
> > An example in INSERT INTO SELECT patch:
> > +/*
> > + * IsModifySupportedInParallelMode
> > + *
> > + * Indicates whether execution of the specified table-modification
> > +command
> > + * (INSERT/UPDATE/DELETE) in parallel-mode is supported, subject to
> > +certain
> > + * parallel-safety conditions.
> > + */
> > +static inline bool
> > +IsModifySupportedInParallelMode(CmdType commandType) {
> > + /* Currently only INSERT is supported */
> > + return (commandType == CMD_INSERT); }
>
> The intention of assert is to verify that those functions are called for
> appropriate commands such as CTAS, Refresh Mat View and so on with correct
> parameters. I really don't think so we can replace the assert with a function
> like above, in the release mode assertion will always be true. In a way,
> that assertion is for only debugging purposes. And I also think that when
> we as the callers know when to call those new functions, we can even remove
> the assertions, if they are really a problem here. Thoughts?
Hi

Thanks for the explanation.

If the check about command type is only used in assert, I think you are right.
I suggested a new function because I guess the check can be used in some other places.
Such as:

+ /* Okay to parallelize inserts, so mark it. */
+ if (ins_cmd == PARALLEL_INSERT_CMD_CREATE_TABLE_AS)
+ ((DR_intorel *) dest)->is_parallel = true;

+ if (ins_cmd == PARALLEL_INSERT_CMD_CREATE_TABLE_AS)
+ ((DR_intorel *) dest)->is_parallel = false;

Or

+ if (fpes->ins_cmd_type == PARALLEL_INSERT_CMD_CREATE_TABLE_AS)
+ pg_atomic_add_fetch_u64(&fpes->processed, queryDesc->estate->es_processed);

If you think the above code will extend the ins_cmd type check in the future, the generic function may make sense.

Best regards,
houzj