标题: 请教高手，望赐教 [打印本页] 作者: 大约在冬季 时间: 2005-07-18 10:03 标题: 请教高手，望赐教 我写这样一个sql：
echo "BEGIN : `date +%H:%M:%S`"
dbaccess cisdb <<EOF
SET EXPLAIN ON;
SET EXPLAIN ON AVOID_EXECUTE;
SET ISOLATION DIRTY READ;
SET PDQPRIORITY HIGH;
insert into tmp_all_savestat select --+ use_hash(a,b)
a.branchno_cr,'99',sum(nvl(b.balance_dc,0))
from t_cif_info a,t_acct_info b
where
a.custno_i=b.custno_i
and b.acctorig_cr !='4' and b.acctstatus_cr !='2'
group by a.branchno_cr;
SET EXPLAIN OFF;
EOF
echo "END : `date +%H:%M:%S`"
执行结果非常慢，跟踪显示两个表都是顺序扫描，根本没用到索引，请问问题出在哪里？
附跟踪结果：
Estimated Cost: 2147483647
Estimated # of Rows Returned: 12
Maximum Threads: 13
DIRECTIVES FOLLOWED:
USE_HASH ( a b )
DIRECTIVES NOT FOLLOWED:
Temporary Files Required For: Group By
1) ccbcis.b: SEQUENTIAL SCAN
Filters: (ccbcis.b.acctorig_cr != '4' AND ccbcis.b.acctstatus_cr != '2'
)