On 6/4/20 11:00 AM, Kyotaro Horiguchi wrote:
Removed a useless variable PgFdwScanState.result_ready.
Removed duplicate code from remove_async_node() by using move_to_next_waiter().
Done some minor cleanups.
I am reviewing your code.
A couple of variables are no longer needed (see changes.patch in attachment.
Something about the cost of an asynchronous plan:
At the simple query plan (see below) I see:
1. Startup cost of local SeqScan is equal 0, ForeignScan - 100. But
startup cost of Append is 0.
2. Total cost of an Append node is a sum of the subplans. Maybe in the
case of asynchronous append we need to use some reduce factor?
explain select * from parts;
With Async Append:
=====================
Append (cost=0.00..2510.30 rows=106780 width=8)
Async subplans: 3
-> Async Foreign Scan on part_1 parts_2 (cost=100.00..177.80
rows=2260 width=8)
-> Async Foreign Scan on part_2 parts_3 (cost=100.00..177.80
rows=2260 width=8)
-> Async Foreign Scan on part_3 parts_4 (cost=100.00..177.80
rows=2260 width=8)
-> Seq Scan on part_0 parts_1 (cost=0.00..1443.00 rows=100000 width=8)
Without Async Append:
=====================
Append (cost=0.00..2510.30 rows=106780 width=8)
-> Seq Scan on part_0 parts_1 (cost=0.00..1443.00 rows=100000 width=8)
-> Foreign Scan on part_1 parts_2 (cost=100.00..177.80 rows=2260
width=8)
-> Foreign Scan on part_2 parts_3 (cost=100.00..177.80 rows=2260
width=8)
-> Foreign Scan on part_3 parts_4 (cost=100.00..177.80 rows=2260
width=8)
--
Andrey Lepikhov
Postgres Professional
https://postgrespro.com
The Russian Postgres Company
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index b04b6a0e54..4406a9c3b3 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -1632,9 +1632,6 @@ remove_async_node(ForeignScanState *node)
if (leader == node)
{
- /* It's the leader */
- ForeignScanState *next_leader;
-
if (leader_state->s.commonstate->busy)
{
/*
@@ -1769,7 +1766,7 @@ postgresIterateForeignScan(ForeignScanState *node)
node->ss.ps.asyncstate = AS_AVAILABLE;
else
node->ss.ps.asyncstate = AS_WAITING;
-
+elog(WARNING, "No tuple result %d", fsstate->cursor_number);
return ExecClearTuple(slot);
}
@@ -3703,7 +3700,7 @@ request_more_data(ForeignScanState *node)
snprintf(sql, sizeof(sql), "FETCH %d FROM c%u",
fsstate->fetch_size, fsstate->cursor_number);
-
+elog(WARNING, "FETCH: %s", sql);
if (!PQsendQuery(conn, sql))
pgfdw_report_error(ERROR, NULL, conn, false, sql);
@@ -3769,7 +3766,6 @@ fetch_received_data(ForeignScanState *node)
PG_TRY();
{
PGconn *conn = fsstate->s.conn;
- char sql[64];
int addrows;
size_t newsize;
int i;
@@ -3798,7 +3794,7 @@ fetch_received_data(ForeignScanState *node)
node,
fsstate->temp_cxt);
}
-
+elog(WARNING, "fetch cursor: %d (%d %d)", fsstate->cursor_number, fsstate->num_tuples, addrows);
/* Update fetch_ct_2 */
if (fsstate->fetch_ct_2 < 2 && fsstate->next_tuple == 0)
fsstate->fetch_ct_2++;
