postgressql——子事务可见性判断 性能问题（8）

子事务可见性判断 & 性能

测试SQL

BEGIN;
PREPARE sel(integer) ASSELECT count(*)FROM contendWHERE id BETWEEN $1 AND $1 + 100;
PREPARE upd(integer) ASUPDATE contend SET val = val + 1WHERE id IN ($1, $1 + 10, $1 + 20, $1 + 30);SAVEPOINT a;
\set rnd random(1,990)
EXECUTE sel(10 * :rnd + :client_id + 1);
EXECUTE upd(10 * :rnd + :client_id);SAVEPOINT a;
\set rnd random(1,990)
EXECUTE sel(10 * :rnd + :client_id + 1);
EXECUTE upd(10 * :rnd + :client_id);...SAVEPOINT a;
\set rnd random(1,990)
EXECUTE sel(10 * :rnd + :client_id + 1);
EXECUTE upd(10 * :rnd + :client_id);DEALLOCATE ALL;
COMMIT;

子事务：tps = 167.382164

pgbench -f subtrans.sql -n -c 6 -T 600transaction type: subtrans.sql
scaling factor: 1
query mode: simple
number of clients: 6
number of threads: 1
duration: 600 s
number of transactions actually processed: 100