关于showplan输出
这样看执行计划的输出 它到底有什么用。比如:
QUERY PLAN FOR STATEMENT 80 (at line 236).
STEP 1
The type of query is SELECT (into Worktable1).
GROUP BY
Evaluate Grouped MAXIMUM AGGREGATE.
Evaluate Grouped MAXIMUM AGGREGATE.
FROM TABLE
yy_xshkxx
Nested iteration.
Index : xshkxx_fgsbm_khdm
Ascending scan.
Positioning at index start.
Using I/O Size 2 Kbytes.
With LRU Buffer Replacement Strategy.
TO TABLE
Worktable1.
STEP 2
The type of query is INSERT.
The update mode is direct.
FROM TABLE
Worktable1.
Nested iteration.
Table Scan.
Ascending scan.
Positioning at start of table.
Using I/O Size 2 Kbytes.
With MRU Buffer Replacement Strategy.
TO TABLE
#yf1
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