The SQL order of execution defines the order in which the clauses of a query are evaluated. Some of the most common query challenges people run into could be easily avoided with a clearer understanding of the SQL order of execution, sometimes called the SQL order of operations. Understanding ...
'fields.id.kind'='sequence','rows-per-second'='10');CREATETABLECustomers(idINT,nameSTRING,countrySTRING,zipSTRING,PRIMARYKEY(id)NOTENFORCED)WITH('connector'='jdbc','url'='jdbc:mysql://mysqlhost:3306/customerdb','table-name'='customers');CREATETABLEOrder...
The Index Merge intersection algorithm performs simultaneous scans on all used indexes and produces the intersection of row sequences that it receives from the merged index scans. If all columns used in the query are covered by the used indexes, full table rows are not retrieved (EXPLAIN output ...
SEQUENCE. If you omit the THROUGH clause entirely, this is the default. THROUGH ... SWITCHOVER: The managed standby recovery process normally stops when it encounters a switchover operation, because these operations produce an "end-of-redo archival" indicator. This clause is useful if you have...
1createsequence my_seq2startwith13nomaxvalue4nocycle; 序列也是 Oracle 数据库对象之一,序列有两个常用的属性:nextval、currval。 1selectmy_seq.nextvalfromdual;--获取下一个序列值2selectmy_seq.currvalfromdual;--查看当前序列值3--在插入数据是使用序列4insertintotable_name5values6(my_seq.nextval,...)...
set odps.sql.executionengine.batch.rowcount=16; divide.nan.or.overflow 旧版MaxCompute不会做除法常量折叠的问题。 比如如下语句,旧版MaxCompute对应的物理执行计划如下: explain select if(false, 0/0, 1.0) from table_name; in task M1_Stg1: Data source: meta_dev.table_name TS: alias: table_name...
The log reader doesn't go beyond the minimum acknowledged Log Sequence Number of the SYNCHRONIZED secondaries. This trace flag applies to the instance of SQL Server, not just an availability group, an availability database, or a log reader instance. This trace flag must be enabled on the ...
The output of the Query Optimizer is an execution plan. For more information, see The SQL Server Query Optimizer. Execution plan An execution plan is a definition that sequences the source tables to access and the methods used to extract data from each table. Optimization i...
函数序列错误(FDW_FUNCTION_SEQUENCE_ERROR) HV021 描述信息不一致(FDW_INCONSISTENT_DESCRIPTOR_INFORMATION) HV024 非法属性值(FDW_INVALID_ATTRIBUTE_VALUE) HV007 非法列名称(FDW_INVALID_COLUMN_NAME) HV008 非法列数(FDW_INVALID_COLUMN_NUMBER) HV004 非法数据类型(FDW_INVALID_DATA_TYPE) HV006 非法数据类型...
val aggExprs = aggregateExprs.filter(_.collect { case a: AggregateExpression => a }.nonEmpty) failAnalysis( s"grouping expressions sequence is empty, " + s"and '${e.sql}' is not an aggregate function. " + s"Wrap '${aggExprs.map(_.sql).mkString("(", ", ", ")")}' in ...