1. The statement that has been verified and is exactly the same as the statement in the shared pool 2. The variable name is as possible. 3. Reasonably use the outer joint 4. Small multi-layer nested 5. Multi-purpose concurrency
The optimization steps of statements are generally: 1. Adjust the SGA zone so that the SGA area is optimal. 2. The SQL statement itself is optimized, the tool has Explain, SQL TRACE, etc. 3. Database Structure Adjustment 4. Project Structure Adjusts the experience of write statements: 1. Use index for large tables 2. Use less IN, EXIST, etc. Collect operation
1. For the listed in the big table query, try to avoid conversion 2 such as TO_CHAR, TO_DATE, TO_NUMBER, etc.. There is an index to use an index, and the conditional to index is written in front. If necessary, it is possible to establish some index 3. Try to avoid full mete scan, limit conditions as possible, so as quickly as possible to search the data to be queried
