SQL optimization principles in Oracle

1. The tested statements must be exactly the same as those in the shared pool. Variable names should be the same as 3. Rational Use of Outer Join 4. Use less layer nesting 5. Optimization steps for multi-purpose concurrent statements are generally as follows: 1. Adjust the sga area so that the sga area is optimal. 2. Optimization of SQL statements, including explain and sqltrace. Database Structure

1. The tested statements must be exactly the same as those in the shared pool. Variable names should be the same as 3. Rational Use of Outer Join 4. Use less layer nesting 5. Optimization steps for multi-purpose concurrent statements are generally as follows: 1. Adjust the sga area so that the sga area is optimal. 2. Optimization of SQL statements, including explain and SQL trace. Database Structure

1. The tested statements must be exactly the same as those in the shared pool.

2. Variable names should be as consistent as possible

3. Rational use of external connections

4. Use less multi-layer nesting

5. Multi-purpose concurrency

Statement optimization steps include:

1. Adjust the sga area so that the sga area is optimal.

2. Optimization of SQL statements, including explain and SQL trace tools

3. Database Structure Adjustment

4. Project Structure Adjustment

Statement writing experience:

1. Use indexes for large table queries

2. Use less in and exist

3. Use set operations

1. Do not convert columns in large table queries, such as To_char, to_date, and to_number.

2. Try to use an index if there is an index. The conditions that are useful for the index should be written before. If possible and necessary, create some indexes.

3. Avoid full table scan as much as possible. There are as many restrictions as possible to search for the data to be queried faster.

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