To learn about important explain result fields and how to interpret them, seeInterpret Explain Plan Results. 重要 explainignores the plan cache. Instead, a set of candidate plans are generated, and a winner is chosen without consulting the plan cache. Furthermore,explainprevents the MongoDB query...
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...
Interestingly, the lower-limit, all the way up to the invention of the airplane, seems to stay at about two metres (around 1881, the lowest marked position seems to be only slightly above 1 metre), which might represent the possibility of there always being at leastsomeoneclimbing up a lad...
Only 41 rows were returned (rows=41) but a sequential scan (Seq Scan on kvstore) was performed on all the rows (Storage Rows Scanned: 10000). Also, the data had to be sorted (viaSort Method: quicksort) on value (viaSort Key: value). You can improve this execution by modifying the...
After sending the payment request to the PSP, the payment service keeps asking the PSP about the payment status. After several rounds, the PSP finally returns with the status. Short polling has two drawbacks: Constant polling of the status requires resources from the payment service. ...
are useful for troubleshooting performance of a SQL statement, and especially for working with third parties who are helping in the process. 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...
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...
FALSEProvides additional information about how MAXPAGES is calculated in the case of a jump scan. A jump scan can be conceptualized as multiple contiguous scans separated by jumps. If the value is 'TRUE', then MAXPAGES is the number of pages that are expected to be accessed by each contiguous...
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...
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 ...