MySQL explains how it would process the statement, including information about how tables are joined and in which order. For information about using EXPLAIN to obtain execution plan information, see Section 8.8.2, “EXPLAIN Output Format”. 当...
To use the information that the openCypher explain feature provides, you need to understand some details about how the DFE query engine works (DFE being the engine that Neptune uses to process openCypher queries). The DFE engine translates every query into a pipeline of operators. Starting from...
SORT:Operators and steps used when queries have to sort or merge result sets. SortsortSort performs the sorting specified by the ORDER BY clause as well as other operations such as UNIONs and joins. Can operate from disk. MergemergeProduces final sorted results of a query based on intermediate...
It reduces the amount of back-and-forth requests for information by capturing a great deal of commonly useful data about the performance of a SQL statement.DiffStats 和ExplainFull 可以生成详细的报告,这些报告对于解决SQL 语句的性能问题非常有用。 安装很简单,1分钟搞定,因为是几个纯文本函数,所以 ...
Join method – The method (e.g., hash, sort-merge, etc.) used to join tables with each other. Join type – The type of join (e.g., outer, anti, semi, etc.). Join order – The order in which the tables are joined to each other. Partition pruning – Are...
See Batched Key Access Joins, for information about the Batched Key Access algorithm. Using MRR (JSON property: message) Tables are read using the Multi-Range Read optimization strategy. See Section 10.2.1.11, “Multi-Range Read Optimization”. Using sort_union(...), Using union(...)...
TheEXPLAINstatement provides information about how MySQL executes statements: EXPLAIN常常可以与SELECT、DELETE、INSERT、REPLACE和UPDATE语句一起结合执行。 当EXPLAIN与可解释语句一起使用时,MySQL将显示优化器关于语句执行计划的信息。也就是说,MySQL解释了它将如何处理语句,包括关于表如何联接和顺序的信息。
See Batched Key Access Joins, for information about the Batched Key Access algorithm. Using MRR (JSON property: message) Tables are read using the Multi-Range Read optimization strategy. See Section 10.2.1.11, “Multi-Range Read Optimization”. Using sort_union(...), Using union(...)...
Using sort_union(...), Using union(...), Usingintersect(...) (JSON property: message) Theseindicate how index scans are merged for the index_merge jointype. See Section 9.2.1.4, “Index MergeOptimization”. Using temporary (JSON property: using_temporary_table) ...
Data operations like filter, sort, or aggregation In addition to the row source tree, the plan table contains information about the following: Optimization, such as the cost and cardinality of each operation Partitioning, such as the set of accessed partitions Parallel execution, such as the...