On 14/09/16 20:50, Andres Freund wrote:
On 2016-09-14 13:20:02 -0500, Peter Eisentraut wrote:
On 9/14/16 11:21 AM, Andres Freund wrote:
+       ExecInsert(NULL, /* mtstate is only used for onconflict handling which 
we don't support atm */
+                          remoteslot,
+                          remoteslot,
+                          NIL,
+                          ONCONFLICT_NONE,
+                          estate,
+                          false);
I have *severe* doubts about just using the (newly) exposed functions
1:1 here.

It is a valid concern, but what is the alternative?  ExecInsert() and
the others appear to do exactly the right things that are required.

They're actually a lot more heavyweight than what's required. If you
e.g. do a large COPY on the source side, we create a single executor
state (if at all), and then insert the rows using lower level
routines. And that's *vastly* faster, than going through all the setup
costs here for each row.

Are your concerns mainly philosophical about calling into internal
executor code, or do you have technical concerns that this will not do
the right thing in some cases?

Well, not about it being wrong in the sene of returning wrong results,
but wrong in the sense of not even remotely being able to keep up in
common cases.

I'd say in common case they will. I don't plan to use these forever btw, but it's simplest to just use them in v1 IMHO instead of trying to reinvent new versions of these that perform better but also behave correctly (in terms of triggers and stuff for example).

  Petr Jelinek                  http://www.2ndQuadrant.com/
  PostgreSQL Development, 24x7 Support, Training & Services

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