Micro-class sql optimization (17), no code change, optimization SQL (1)-summary of optimization methods

1. The problem arises: do not change the code, upgrade the version, or expand the configuration, how to optimize sql? As an Oracle database dba, faced with the bottleneck of system performance in the process of SQL optimization, do you also encounter the following dilemmas: 1. The developer is out of insurance and cannot carry out code-level optimization. 2. The code-level modification cycle is too long for enterprises to bear the performance risk, so optimization is urgently needed. 3. The server cannot be expanded or fully configured in a short period of time, and there are still performance problems. 4. The application software does not support it, and the database version cannot be upgraded. In order to help you solve the above problems smoothly, today our topic is "do not change the code, do not upgrade the version, do not expand the configuration, how to optimize SQL"? Star students first discuss optimization methods with you, and then summarize the advantages and disadvantages, applicable scenarios and optimization results of each method from the actual combat. 2. Optimization method