以下是一个sql的showplan，怎么看它是nested loop join还是merge join，哪个的outer table，哪个是inner table，谢谢
QUERY PLAN FOR STATEMENT 1 (at line 1).
Auxiliary scan descriptors required: 6
STEP 1
The type of query is INSERT.
The update mode is direct.
Worktable1 created for REFORMATTING.
FROM TABLE
opr_nodename
n1
Nested iteration.
Table Scan.
Forward scan.(rowtotal 535)
Positioning at start of table.
Using I/O Size 16 Kbytes for data pages.
With LRU Buffer Replacement Strategy for data pages.
TO TABLE
Worktable1.
STEP 2
The type of query is INSERT.
The update mode is direct.
Worktable2 created for REFORMATTING.
FROM TABLE
pr_help(totalrow 12289)
Nested iteration.
Using Clustered Index.
Index : x1_help
Forward scan.
Positioning by key.
Keys are:
hlp_dom_idASC
hlp_lng_idASC
Using I/O Size 16 Kbytes for data pages.
With LRU Buffer Replacement Strategy for data pages.
TO TABLE
Worktable2.
STEP 3
The type of query is SELECT.
FROM TABLE
pr_pargroup
Nested iteration.
Table Scan.
Forward scan. (rowtotal 5)
Positioning at start of table.
Using I/O Size 2 Kbytes for data pages.
With LRU Buffer Replacement Strategy for data pages.
FROM TABLE
rdm_security_dim
rsd
Nested iteration.
Table Scan.
Forward scan. (rowtotal 3750)
Positioning at start of table.
Using I/O Size 16 Kbytes for data pages.
With LRU Buffer Replacement Strategy for data pages.
FROM TABLE
opr_modeldtl(total 42697)
l
Nested iteration.
Index : x2_modeldtl
Forward scan.
Positioning by key.
Keys are:
secidASC
Using I/O Size 16 Kbytes for index leaf pages.
With LRU Buffer Replacement Strategy for index leaf pages.
Using I/O Size 16 Kbytes for data pages.
With LRU Buffer Replacement Strategy for data pages.
