Oracle 查看表有哪些列在谓词条件过滤中！ 有时候在优化的过程当中，需要查看某个表有哪些列在sql当中用作谓词过滤，我们就可以用如下sql查询。 1. 先创建test表 SQL create table test as select * from dba_objects;Table created. 1 2 3 SQL create table
Oracle 查看表有哪些列在谓词条件过滤中！
有时候在优化的过程当中，需要查看某个表有哪些列在sql当中用作谓词过滤，我们就可以用如下sql查询。
1. 先创建test表
SQL> create table test as select * from dba_objects; Table created.
SQL > create table test as select * from dba_objects;
Table created.
2.通过sql查看这个表是否有其他sql用到了这个表的列当作过滤条件
SQL> select 2 r.name owner, 3 o.name table_name , 4 c.name column_name, 5 equality_preds, ---等值过滤 6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id 7 nonequijoin_preds, ----不等JOIN过滤 8 range_preds, ----范围过滤 > >=
SQL > select
2 r. name owner ,
3 o. name table_name,
4 c. name column_name,
5 equality_preds, ---等值过滤
6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id
7 nonequijoin_preds, ----不等JOIN过滤
8 range_preds, ----范围过滤 > >=
9 like_preds, ----LIKE过滤
10 null_preds, ----NULL 过滤
11 timestamp
12 from
13 sys.col_usage$u,
14 sys.obj$o,
15 sys.col$c,
16 sys. user $r
17 where
18 o.obj#=u.obj#
19 and c.obj#=u.obj#
20 and c.col#=u.intcol#
21 and r. name = 'SCOTT' and o. name = 'TEST' ;
no rows selected
3.执行一个简单的sql，用object_id过滤，执行完成之后，再次查看
SQL> select count(*) from test where object_id=23121; COUNT(*) ---------- 1 SQL> select 2 r.name owner, 3 o.name table_name , 4 c.name column_name, 5 equality_preds, ---等值过滤 6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id 7 nonequijoin_preds, ----不等JOIN过滤 8 range_preds, ----范围过滤 > >=
SQL > select count (*) from test where object_id = 23121;
COUNT (*)
----------
SQL > select
2 r. name owner ,
3 o. name table_name,
4 c. name column_name,
5 equality_preds, ---等值过滤
6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id
7 nonequijoin_preds, ----不等JOIN过滤
8 range_preds, ----范围过滤 > >=
9 like_preds, ----LIKE过滤
10 null_preds, ----NULL 过滤
11 timestamp
12 from
13 sys.col_usage$u,
14 sys.obj$o,
15 sys.col$c,
16 sys. user $r
17 where
18 o.obj#=u.obj#
19 and c.obj#=u.obj#
20 and c.col#=u.intcol#
21 and r. name = 'SCOTT' and o. name = 'TEST' ;
no rows selected
4. 这里可能就有疑问了，在第三步中有sql使用object_id谓词进行过滤，为什么sql还是不查询到呢？因为此时信息还没刷新到磁盘
SQL> select 2 r.name owner, 3 o.name table_name , 4 c.name column_name, 5 equality_preds, ---等值过滤 6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id 7 nonequijoin_preds, ----不等JOIN过滤 8 range_preds, ----范围过滤 > >=
SQL > select
2 r. name owner ,
3 o. name table_name,
4 c. name column_name,
5 equality_preds, ---等值过滤
6 equijoin_preds, ---等值JOIN过滤 比如where a.id=b.id
7 nonequijoin_preds, ----不等JOIN过滤
8 range_preds, ----范围过滤 > >=
9 like_preds, ----LIKE过滤
10 null_preds, ----NULL 过滤
11 timestamp
12 from
13 sys.col_usage$u,
14 sys.obj$o,
15 sys.col$c,
16 sys. user $r
17 where
18 o.obj#=u.obj#
19 and c.obj#=u.obj#
20 and c.col#=u.intcol#
21 and r. name = 'SCOTT' and o. name = 'TEST' ;
OWNER TABLE_NAME COLUMN_NAME EQUALITY_PREDSEQUIJOIN_PREDSNONEQUIJOIN_PREDSRANGE_PREDSLIKE_PREDSNULL_PREDS TIMESTAMP
-------------------- -------------------- -------------------- -------------- -------------- ----------------- ----------- ---------- ---------- ---------
SCOTT TEST OBJECT_ID 1 0 0 0 0 031 - MAR - 14
SCOTT TEST OBJECT_ID 1 0 0 0 0 031 - MAR - 14
在过了一段时间之后，通过这个sql就可以查询到TEST表就有object_id这个列被sql当作谓词条件了。另外可以通过如下sql来刷新当前内存信息到磁盘，这样也可以立即看到信息
SQL> exec dbms_stats.flush_database_monitoring_info; PL/SQL procedure successfully completed.
SQL > execdbms_stats.flush_database_monitoring_info;
PL / SQL procedure successfullycompleted.
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