What is a top K query?
2. Top-k Queries: The top-k query is define as- Given a database D of m objects, each of which is characterized by n attributes, a scoring function f, according to which we rank the objects in D, and the number of expected results k. Then a top-k query Q returns the k objects with the highest rank in f.
What is query processing in distributed database?
Distributed query processing is the procedure of answering queries (which means mainly read operations on large data sets) in a distributed environment where data is managed at multiple sites in a computer network.
What is query processor in DBMS with example?
The query processor is the subcomponent of the data server that processes SQL requests. The SQL requests can access a single database or file system or reference multiple types of databases or file systems.
What is query optimization in distributed database?
Distributed query optimization refers to the process of producing a plan for the processing of a query to a distributed database system. The plan is called a query execution plan. In a distributed database system, schema and queries refer to logical units of data.
What is top K sort?
Overview. Top K Sort is a sorting algorithm which is used to calculate the maximum or the minimum K number of elements in the input stream. The algorithm is quite easy, and we can only get one data per clock due to the design requirements in L2 API.
What are the components of query processor?
Typically, a query processor consists of four sub-components; each of them corresponds to a different stage in the lifecycle of a query. The sub-components are the query parser, the query rewriter, the query optimizer and the query executor [3].
What are the 4 main phases of query processing?
➢ Four main Phases: decomposition, optimization, code generation and execution.
What is the processor in SQL?
The SQL Processor is for continuously processing a data stream. As streaming data can never end, you will have to have ways to bypass this fact when you write certain types (aggregates/joins) of queries over live data.
What are the components of query processor in DBMS architecture?
What is query processing and query optimization in database?
Page 1. Query Optimization. Query Processing: Query processing refers to activities including translation of high level languages (HLL) queries into operations at physical file level, query optimization transformations, and actual evaluation of queries.
What is query processing?
Definition. Query processing denotes the compilation and execution of a query specification usually expressed in a declarative database query language such as the structured query language (SQL). Query processing consists of a compile-time phase and a runtime phase.
What is top K problem?
The Top-K problem is related to the problem of deter- mining order statistics for a collection of numbers. A well- known linear-time algorithm for computing the ith order statistic of a list of numbers is presented in Blum et al. (1973) and Floyd and Rivest (1973).