Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> writes:
> On Mon, Mar 23, 2015 at 10:51 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Hm? We don't have scan nodes that read more than one table, so I'm
>> not following your point.
> But in the text output you gave
> Update on public.pt1 (cost=0.00..321.05 rows=3541 width=46)
> Update on public.pt1
> Foreign Update on public.ft1
> Remote SQL: UPDATE public.ref1 SET c1 = $2 WHERE ctid = $1
> Foreign Update on public.ft2
> Remote SQL: UPDATE public.ref2 SET c1 = $2 WHERE ctid = $1
> Update on public.child3
> -> Seq Scan on public.pt1 (cost=0.00..0.00 rows=1 width=46)
> Output: (pt1.c1 + 1), pt1.c2, pt1.c3, pt1.ctid
> ... etc ...
> For ft1 there is only Update Remote SQL. whereas for child3 you have
> specified the Seq Scan as well.
I think you're confused by my perhaps-overly-abbreviated example.
Here's the whole output for the example in HEAD:
# explain update pt1 set c1=c1+1; QUERY PLAN
---------------------------------------------------------------------Update on pt1 (cost=0.00..321.05 rows=3541
width=46) Update on pt1 Foreign Update on ft1 Foreign Update on ft2 Update on child3 -> Seq Scan on pt1
(cost=0.00..0.00rows=1 width=46) -> Foreign Scan on ft1 (cost=100.00..148.03 rows=1170 width=46) -> Foreign Scan
onft2 (cost=100.00..148.03 rows=1170 width=46) -> Seq Scan on child3 (cost=0.00..25.00 rows=1200 width=46)
(9 rows)
# explain verbose update pt1 set c1=c1+1; QUERY PLAN
----------------------------------------------------------------------------Update on public.pt1 (cost=0.00..321.05
rows=3541width=46) Update on public.pt1 Foreign Update on public.ft1 Remote SQL: UPDATE public.ref1 SET c1 = $2
WHEREctid = $1 Foreign Update on public.ft2 Remote SQL: UPDATE public.ref2 SET c1 = $2 WHERE ctid = $1 Update on
public.child3 -> Seq Scan on public.pt1 (cost=0.00..0.00 rows=1 width=46) Output: (pt1.c1 + 1), pt1.c2,
pt1.c3,pt1.ctid -> Foreign Scan on public.ft1 (cost=100.00..148.03 rows=1170 width=46) Output: (ft1.c1 + 1),
ft1.c2,ft1.c3, ft1.ctid Remote SQL: SELECT c1, c2, c3, ctid FROM public.ref1 FOR UPDATE -> Foreign Scan on
public.ft2 (cost=100.00..148.03 rows=1170 width=46) Output: (ft2.c1 + 1), ft2.c2, ft2.c3, ft2.ctid Remote
SQL:SELECT c1, c2, c3, ctid FROM public.ref2 FOR UPDATE -> Seq Scan on public.child3 (cost=0.00..25.00 rows=1200
width=46) Output: (child3.c1 + 1), child3.c2, child3.c3, child3.ctid
(17 rows)
regards, tom lane