Query Text:selectname,settingfromsys_settingswherenamelike'auto_explain%';FunctionScanonpg_show_all_settings a (cost=0.00..12.50rows=1width=64) (actualtime=0.832..0.852rows=12loops=1)Filter: (name~~'auto_explain%'::text)RowsRemovedbyFilter:490-- delete from t1;执行计划,执行了1次2023-10-2...
执行EXPLAIN 命令: 使用你要分析的查询替换 query,然后执行 EXPLAIN 命令。例如: 复制 EXPLAIN SELECT * FROM table_name WHERE column_name = 'value'; 1. 解读查询计划输出: 查询计划输出包含多个部分,每个部分描述了查询计划中的一个操作。以下是一些常见的关键信息: QUERY PLAN:整个查询计划的概述。 ->:表示...
suppressed options COST and BYTES The Note Section In addition to the plan and the predicate information, the DBMS_XPLAN package displays additional information in the NOTE section, such as when dynamic sampling was used during query optimization or that star transformation was applied to the query...
(6) index:the index tree is scanned, MySQL can use this type when the query uses only columns that are part of a single index. 表示全索引扫描(full index scan), 和ALL类型类似, 只不过ALL类型是全表扫描, 而index类型则仅仅扫描所有的索引, 而不扫描数据. mysql> explain select book_name from...
That is, MySQL explains how it would process the statement, including information about how tables are joined and in which order. For information about using EXPLAIN to obtain execution plan information, see Section 10.8.2, “EXPLAIN Output Format”. When EXPLAIN is used with FOR CONNECTION ...
The FOREIGN KEY relationship plays the main part in this process as tables must be related to each other. Let us have a look at the scenario for MySQL EXPLAIN with example: we created external keys for a table we wanted to execute a query for. Then, we ran the query with the Query ...
EXPLAIN format = TRADITIONAL json SELECT tt.TicketNumber, tt.TimeIn, tt.ProjectReference, tt.EstimatedShipDate, tt.ActualShipDate, tt.ClientID, tt.ServiceCodes, tt.RepetitiveID, tt.CurrentProcess, tt.CurrentDPPerson, tt.RecordVolume, tt.DPPrinted, et.COUNTRY, ...
If SQL query performance is poor or query results do not meet expectations, you can execute the EXPLAIN and EXPLAIN ANALYZE statements in Hologres to obtain execution plans of query statements. This way, you can optimize query statements or database structures. This topic describes how to execute...
One of the most important skills you can have as a ClickHouse user is query optimization. This will get you started. EXPLAIN SYNTAX If you’re not familiar yet with the EXPLAIN statement head over to thedocumentationand have a look. This is your best friend when debugging queries in ClickHou...
Oracle Database PL/SQL Packages and Types Reference for more information on the DBMS_XPLAN package 12.4.1 Customizing PLAN_TABLE Output If you have specified a statement identifier, then you can write your own script to query the PLAN_TABLE. For example: Start with ID = 0 and given STATEMEN...