customNum=100 orderNum=200 rm tmp rm custom.sql for i in `seq $customNum`; do uuid=$(uuidgen) echo $uuid >> tmp done ## custom.sql文件为向t_custom表插入数据的sql awk -v LINE_NUM=$customNum 'BEGIN{ srand(); for(i=1;i<=LINE_NUM;i++) { a[i]=int(rand()*10000%100); ...
the MySQL optimizer considers many techniques to efficiently performthe lookups involved in an SQL query. A query on a huge table can be performedwithout reading all the rows; a join involving several tables can be performedwithout comparing every combination of rows. The set of operations...
(subquery in condition; run only once; shared access) -> Aggregate: sum(`<collector>`.tmp_field_0) (cost=825576.85 rows=1) -> Gather (slice: 1; workers: 256; nodes: 16) (cost=825564.05 rows=256) -> Aggregate: sum((partsupp.PS_SUPPLYCOST * partsupp.PS_AVAILQTY)) (cost=825541.20...
EXPLAIN ANALYZE:代表SQL真实的运行计划,相比EXPLAIN会包含更多的实际运行信息,能准确的反映出SQL的执行算子和算子耗时,可以根据算子耗时去做针对性的SQL优化。 说明 从Hologres V1.3.4x版本开始,支持通过EXPLAIN和EXPLAIN ANALYZE查看更加清晰且阅读性更高的执行计划,本文档基于V1.3.4x版本撰写,建议将实例升级至V1.3....
if (!ji || ji->created_functions == 0) return; /* calculate total time */ INSTR_TIME_SET_ZERO(total_time); INSTR_TIME_ADD(total_time, ji->generation_counter); INSTR_TIME_ADD(total_time, ji->inlining_counter); INSTR_TIME_ADD(total_time, ji->optimization_counter); INSTR_TIME_ADD(...
For example, if a hash aggregate operator is used in the first step of a query plan, full data of downstream operators is required to create a hash table for an aggregate operation. For common queries with filter conditions, data is calculated and returned in real time. In this scenario, ...
doris Aggregate查询rollup explain 查询 1. explain的作用: 例如: 1、id:id的值越大则代表越先执行。 2、select_type:常见的主要有如下六个:主要用于区别普通查询、联合查询、子查询等复杂的查询。 simple:简单的select查询,并且查询中不含子查询或者union。
AggregateaggrOperator/step for scalar aggregate functions. HashAggregateaggrOperator/step for grouped aggregate functions. Can operate from disk by virtue of hash table spilling to disk. GroupAggregateaggrOperator sometimes chosen for grouped aggregate queries if the Amazon Redshift configuration setting for...
也只能启动8个计划工作进程中的7个。1.您正在遇到the documentation中所示的障碍物之一。
The querycontained only aggregate functions (MIN(), MAX()) that were all resolved usingan index, or COUNT(*) for MyISAM, and no GROUP BY clause. The optimizerdetermined that only one row should be returned.2.3.15 Skip_open_table, Open_frm_only,Open_trigger_only, Open_full_table...