Optimizing join enumeration in transformation-based query optimizers
نویسندگان
چکیده
منابع مشابه
Optimizing Join Enumeration in Transformation-based Query Optimizers
Query optimizers built on the Volcano/Cascades framework, which is based on transformation rules, are used in many commercial databases. Transformation rulesets proposed earlier for join order enumeration in such a framework either allow enumeration of joins with cross-products (which can significantly increase the cost of optimization), or generate a large number of duplicate derivations. In t...
متن کاملThe Complexity of Transformation-Based Join Enumeration
Query optimizers that explore a search space exhaustively using transformation rules usually apply all possible rules on each alternative, and stop when no new information is produced. A memoizing structure was proposed in [McK93] to improve the re-use of common subexpression, thus improving the efficiency of the search considerably. However, a question that remained open is, what is the comple...
متن کاملOptimizing Join Query In Distributed Databases
Query Optimization is to use the best plan for the query that improves the performance of the query. Query Optimization is difficult in distributed databases as compared to centralized databases. Queries in distributed databases are effected by factors such as insertion methods of the data into the remote server and transmission time between servers. Response time of the query depends upon the ...
متن کاملMeasuring the Complexity of Join Enumeration in Query Optimization
Since relational database management systems typically support only diadic join operators as primitive operations, a query optimizer must choose the “best” scquence of two-way joins to achieve the N-way join of tables requested by a query. The computational complexity of this optimization process is dominated by the number of such possible sequences that must bc evaluated by the optimizer. This...
متن کاملDuplicate-Free Generation of Alternatives in Transformation-Based Optimizers
Transformation-based optimizers that explore a search space exhaustively usually apply all possible transformation rules on each alternative, and stop when no new information is produced. In general, diierent sequences of transformation rules may end up deriving the same element. The optimizer must detect and discard these duplicate elements generated by multiple paths. In this paper we conside...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Proceedings of the VLDB Endowment
سال: 2014
ISSN: 2150-8097
DOI: 10.14778/2732977.2732997