Oracle's optimization

Lowering the water level line

As the database table space is used for a long time, the amount of data continues to increase, and periodically delete some unimportant data information

Of course, the data can be deleted using the DELETE statement, but the tablespace is not freed

This is because the use will have traces in, so when the delete operation is completed,

Re-use

ALTER TABLE TABLENAME move

Refactoring a data table

Restore normal watermark

Data Table 0 Data

Space remaining in table space (unit: M)

After adding n data

Space remaining in table space (unit: M)

It's clear that the table space is starting to be used

Periodically delete unimportant data to free up tablespace

Delete data

is deleting

But after deletion, the table space is not released

Workaround

Use ALTER TABLE TABLENAME move to refactor the table

After the table is refactored,

Table space water level is naturally restored.

SQL statements

Query spents 1.796 seconds

Query spents 1.598 seconds

Oracle's optimization