Why using bind variables?
When bind variables are used, Oracle can cache the execution plan for a SQL query. The execution plan is the series of steps Oracle takes to execute the query. By using bind variables, Oracle can reuse the same plan even if the literal values in the query change. This minimizes the overhead of generating a new execution plan for every query with different literal values. When queries are executed with bind variables, Oracle does not need to parse the query repeatedly when different values are passed, as the SQL query structure remains the same. This reduces the "parse time" that would otherwise be needed for every execution with different literals. Bind variables help prevent SQL injection attacks because the user input is treated as a parameter rather than part of the SQL query string. The input is not directly inserted into the query, but instead passed as a separate entity, reducing the risk of malicious code execution. Since the execution plan is cached and reused, it reduces memory usage on the database. This is because the SQL statement itself (with bind variables) is stored in the shared pool, and the specific query execution plan is reused when the same query is executed with different values.
Oracle can hash the SQL execution plans that are generated by queries using bind variables. When the same query (with different bind variable values) is executed, Oracle uses the hash of the execution plan to check if it can reuse an existing plan from the Shared Pool. Why this is important? Using bind variables increases the likelihood that the same execution plan is reused. Oracle hashes the execution plan and stores it in the Shared Pool, making it easier to retrieve and avoid recalculating the plan for each unique query execution with different bind values.
VMware SDDC Specialist | Tanzu Architect | HPE Server & Storage Expert | DELL Storage Expert
1 个月Interesting