Query optimization is an important aspect of database management systems (DBMS) as it aims to improve the performance of queries and reduce the execution time. There are several techniques used in query optimization, such as indexing, query rewriting, and query execution plan generation. However, query translation is not a query optimization technique used in a DBMS.

Indexing:
- Indexing is a technique used to improve the performance of queries by creating data structures called indexes on the columns of a table.
- These indexes allow the DBMS to locate and retrieve the required data more efficiently, as they provide a direct access path to the data.
- By using indexes, the number of disk I/O operations and the amount of data that needs to be scanned can be significantly reduced, resulting in faster query execution.

Query Rewriting:
- Query rewriting involves transforming a given query into an equivalent but more efficient form.
- This technique aims to simplify and optimize the query by applying various rewrite rules and transformations.
- For example, query rewriting can involve eliminating unnecessary subqueries, combining multiple queries into a single query, or reordering join operations for better performance.

Query Execution Plan Generation:
- Query execution plan generation is the process of determining the most efficient way to execute a query.
- The DBMS analyzes the query and generates a plan that outlines the steps and operations required to retrieve the requested data.
- The plan includes information about which tables to access, the order of table access, the join operations to perform, and the access methods to use.
- The goal of query execution plan generation is to minimize the overall cost of executing the query, taking into account factors such as data distribution, available indexes, and system resources.

Query Translation:
- Query translation, also known as query parsing or query analysis, is the initial step in query processing.
- It involves parsing the query statement to understand its syntax and semantics.
- The DBMS checks the query for syntactic errors, resolves references to tables and columns, and verifies the integrity of the query.
- Query translation is essential for ensuring that the query is well-formed and can be executed by the DBMS.
- However, it is not considered a query optimization technique as it does not involve any optimization or performance improvement strategies.

In conclusion, query translation is not a query optimization technique used in a DBMS. It is a necessary step in query processing, but it does not involve any optimization strategies to improve query performance.