<dsql_query>最上層/文件元素。 <sql>回應SQL_statement。 <params>目前不使用此標記。 <materialized_view_candidates> (預覽)包含建議具體化檢視的 CREATE 陳述式,可讓 SQL 陳述式有較好的效能。 <dsql_operations>摘要說明和包含查詢步驟,並包含查詢的成本資訊。 也包含所
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...
theMySQLoptimizerconsidersmanytechniquestoefficientlyperformthelookupsinvolvedinanSQLquery.Aqueryonahugetablecanbeperformedwithoutreadingalltherows;ajoininvolvingseveraltablescanbeperformedwithoutcomparingeverycombinationofrows.Thesetofoperationsthattheoptimizerchoosestoperformthemostefficientqueryiscalledthe“queryexecution...
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...
If you want to query execution plans with higher readability, we recommend that you upgrade your Hologres instance to V1.3.4x or later. EXPLAIN Syntax You can execute the following EXPLAIN statement to query the execution plan that is estimated by the QO: EXPLAIN <sql>; Example In this ...
(AWR) SQL Tuning Set (STS) SQL Plan Baseline (SPM) Using the EXPLAIN PLAN Command and the DBMS_XPLAN.DISPLAY Function The following examples illustrate how to generate and display an execution plan for our original SQL statement using the different functions provided in the DBMS_...
Query Profiler对于SQL性能分析和诊断非常有用。另外,该命令还有如下参数可以选择: ALL - displays all information BLOCK IO - displays counts for block input and output operations CONTEXT SWITCHES - displays counts for voluntary and involuntary context switches ...
The execution plan for a specific Amazon Redshift query statement breaks down execution and calculation of a query into a discrete sequence of steps and table operations that eventually produce a final result set for the query. For information about query planning, seeQuery processing. ...
probe: The total time consumed by the main IndexJoin thread to perform join operations with the hash table of the outer table rows and the inner table rows. IndexHashJoin The execution process of the IndexHashJoin operator is similar to that of the IndexJoin operator....
For the execution process of HashJoin_27, TiDB performs the following operations in order: Cache the data of the Build side in memory. Construct a Hash Table on the Build side based on the cached data. Read the data at the Probe side. Use the data of the Probe side to probe the Hash...