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 SQ
非法转义序列(INVALID_ESCAPE_SEQUENCE) 22P06 非标准使用转义字符(NONSTANDARD_USE_OF_ESCAPE_CHARACTER) 22010 非法指示器参数值(INVALID_INDICATOR_PARAMETER_VALUE) 22023 非法参数值(INVALID_PARAMETER_VALUE) 2201B 非法正则表达式(INVALID_REGULAR_EXPRESSION) 2201W LIMIT子句中行号非法(INVALID_ROW_COUNT_IN_LIMIT...
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...
'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...
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 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...
第十九步:lazy val executedPlan: SparkPlan = prepareForExecution(sparkPlan) 执行前的一些准备工作 protected def prepareForExecution(plan: SparkPlan): SparkPlan = { //将规则遍历应用到plan preparations.foldLeft(plan) { case (sp, rule) => rule.apply(sp) } } /** A sequence of rules that wil...
(OCISnapshot *) 0, OCI_DEFAULT); /* Convert next result set to statement handle */ OCIResultSetToStmt(rset, ERRH); rstmt = (OCIStmt *) rset; /* Now rstmt will point to the second result set returned by the remote stored procedure */ /* Repeat execution of get_next_result_set...
论文中也继承pipeline breaker的思想,将QEP拆解成linear sequence operators ,通过topologically sorting来觉得每个pipeline之间的顺序。 2 compiling simple/complex operators simple: Neumann, generate data-centric data complex: 需要一些复杂的数据结构和算法来实现,论文以Hash-based Grouping & Aggregaton为例,下游的...
从10g开始,v$sql_plan中就包括了SQL语句OUTLINE数据,也就是稳定执行计划的Hints。 从下面可以看到: SELECT t1.*, t2.owner FROM t1, t2 WHERE t1.object_name LIKE '%T1%' AND t1.object_id = t2.object_id; select * from table(dbms_xplan.display_cursor(null,null,'outline')); ...