in:当B表的数据集小于A表的数据集时,in优于exists select*fromAwhereidin(selectidfromB) #等价于:for(selectidfromB){select*fromAwhereA.id=B.id } exis`ts:当A表的数据集小于B表的数据集时,exists优于in 将主查询A的数据,放到子查询B中做条件验证,根据验证结果(true或false)来决定主查询的数据是否保...
B:const:使用唯一索引或者主键,返回记录一定是1行记录的等值where条件时,通常type是const。其他数据库也叫做唯一索引扫描 C:eq_ref:出现在要连接过个表的查询计划中,驱动表只返回一行数据,且这行数据是第二个表的主键或者唯一索引,且必须为not null,唯一索引和主键是多列时,只有所有的列都用作比较时才会出现eq_...
SELECT DISTINCT GRANTEE, GRANTEETYPE, 'DATABASE' FROM SYSCAT.DBAUTH UNION SELECT DISTINCT GRANTEE, GRANTEETYPE, 'TABLE ' FROM SYSCAT.TABAUTH UNION SELECT DISTINCT GRANTEE, GRANTEETYPE, 'PACKAGE ' FROM SYSCAT.PACKAGEAUTH UNION SELECT DISTINCT GRANTEE, GRANTEETYPE, 'INDEX ' FROM SYSCAT.INDEXAUTH UNI...
WITH(DATA_COMPRESSION=PAGE);</sql_operation>25</sql_operations>26</dsql_operation>27<dsql_operationoperation_type="BROADCAST_MOVE">28<operation_costcost="0.121431552"accumulative_cost="0.121431552"average_rowsize="16"output_rows="31.6228"/>29SELECT [T1_1].[CustomerKey] AS [CustomerKey], 30 ...
[default_catalog, default_database, alan_ticker2]]) == Optimized Physical Plan == Match(partitionBy=[symbol], orderBy=[rowtime ASC], measures=[FINAL(C.price) AS lastPrice, FINAL(CAST(C.rowtime AS TIMESTAMP(3))) AS rowtime], rowsPerMatch=[ONE ROW PER MATCH], after=[SKIP PAST LAST...
checking a column datatype in a datatable checking for characters in a byte array Checking for exception type in try/catch block in C# checking for non null values in a column checking if a connection is valid Checking if a specific handler exists Checking if an ObservableCollection contains ...
TENANTNM: (Compiled In Tenant Name) SYSTEM Input Streams: --- 2) From Operator #2 Estimated number of rows: 7 Number of columns: 14 Subquery predicate ID: Not Applicable Column Names: --- +Q2.ACTUAL_VALUE+Q2.ACTUAL_TYPE+Q2.HOW_APPLIED +Q2.PREDICATE_ID+Q2.DBPARTITION...
Access method – The way in which the data is being accessed, via either a table scan or index access. 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...
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Cause: The capability in question is not supported when the materialized view uses RAW data type in an expression. Action: Remove the reference to the RAW expression. QSM-02014 GROUP BY expression other than a column Cause: The capability in question is not supported when the materialized view...