10053トレースの Level 1 と 2 の違い

Oracle Database の 10053 トレースの Level は 1 と 2 があり、2 のうほうが情報量が少ない（オプティマイザに使われた初期化パラメータなどが出力されない）。

You have a choice of two levels with the 10053 trace event. Level 1 is more comprehensive than level 2. What is collected in the trace file includes:

1. Parameters used by the optimizer (level 1 only)
2. Index statistics (level 1 only)
3. Column statistics
4. Single Access Paths
5. Join Costs
6. Table Joins Considered
7. Join Methods Considered (NL/MS/HA)

10053 Trace Tips

Cost-Based Oracle Fundamentals

CHAPTER 14 The 10053 Trace File

To enable the 10053 trace, you need to issue one of these statements:

alter session set events '10053 trace name context forever';
alter session set events '10053 trace name context forever, level 1';
alter session set events '10053 trace name context forever, level 2';

The first two do exactly the same thing—the last option produces a slightly shorter trace file because it doesn't include the optimizer parameter listing that is normally at the start of the trace file.

関連

• クエリ・オプティマイザによってビューを参照している SQL が書換えられているか確認する - ablog