Model.aggregate(..).explain(callback) you don't find anyone saying something good. This is a little strange, because, for example on that code with where(), or if you put find() and then explain(), you don't need to wrap the whole code in a console, to get the explain() output...
? rows │ Group by: {} │ Aggregates: expr#sum(total_bytes):=AggNull(sum)(total_bytes) └─ TableScan system.tables Est. ? rows Outputs: [total_bytes] SQL EXPLAIN 类型 AST— 抽象语法树 SYNTAX— 经过 AST-level 优化后的查询文本。 QUERY TREE— 优化后的查询树。 PLAN— 查询计划 ...
GroupByOperator (AGGREGATE): describes the logic of aggregate operations. This operator is displayed if an aggregate function is used in a query statement. The content of the aggregate function is displayed in the execution results of the EXPLAIN statement. ReduceSinkOperator (RS): describes the ...
For example, an inner join query with predicate on one table can be rewritten into a CrossJoin. This pushes the predicate down to the scanning phase of the table so that fewer data are scanned. Join distribution types Distribution types define how data is exchanged between worker nodes when ...
1. What is the purpose of setting the first derivative equal to zero in the optimization process? 2. Suppose you are optimizing a function with the highest power of 3, describe how you would determin What is the difference between use and non-use va...
Explain the aggregate demand. Describe demand function. What are the characteristics of the law of demand and supply? Briefly explain Supply and Demand. Are there any situations where the law of demand fails, and therefore with an increase in price, the demand still increases? Explain. ...
Replace invalid characters with dashes, * so that for example "I/O Read Time" becomes "I-O-Read-Time". */static voidExplainXMLTag(const char *tagname, int flags, ExplainState *es){ const char *s; const char *valid = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_."; ...
unionM,N: The row refers to the union of the rows with id values of M and N. derivedN: The row refers to the derived table result for the row with an id value of N. A derived table may result, for example, from a subquery in the FROM clause. ...
For example, join conditions and WHERE clause restrictions are included in this column. Sample queries Consider the following EXPLAIN output for an aggregate join query: explain select avg(datediff(day, listtime, saletime)) as avgwait from sales, listing where sales.listid = listing.listid...
In the following example, you can see the CPU time that is spent in each stage, along with the relative cost of each plan node in the stage. The relative cost of the plan nodes is based on wall time, which might or might not be correlated to CPU time. For each plan node you can...