I have a watch T,
This table is a list of the ID column, type number,
There is one to ten million line sequence values, has a unique index;

Write a SQL statement
Select * from t where id=1

Find out how slow, optimization of him

CodePudding user response:

Look at the execution plan

CodePudding user response:

1, see the table below the index of state
2, see the table below have no normal undo processing wait for events

CodePudding user response:

Estimation is not collecting statistics, walked a full table scan, collect the statistics first,
Analyze table t compute statistics;