除非您指定-help選項,否則必須指定 package-options 或 dynamic-options。 您可以使用單一呼叫db2expln來說明套件及動態 SQL。 先前列出的部分選項旗標對您的作業系統可能有特殊意義,因此在db2expln指令行中可能無法正確解譯。 不過,您可以在這些字元之前加上作業系統跳出字元,以輸入這些字元。 如需相關資訊,請
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...
db2expln ツールは、SQL ステートメントおよび XQuery ステートメント用に選択されたアクセス・プランを記述します。
Fortunately, PostgreSQL provides us with the option to execute the query as well. To do so, we need to use EXPLAIN ANALYZE instead of just EXPLAIN: SQL Copy to clipboard EXPLAIN ANALYZE SELECT COUNT(*) FROM projects WHERE visibility_level IN (0, 20);...
Explain complex systems using visuals and simple terms. Whether you're preparing for a System Design Interview or you simply want to understand how systems work beneath the surface, we hope this repository will help you achieve that. Table of Contents ...
A user with theVIEWACTIVITYsystem privilegecan generate a bundle for any statement. To grant this privilege, issue the following SQL commands. Replace{user}with the user's ID. ALTERUSER{user}WITHVIEWACTIVITY;GRANTSYSTEMVIEWSYSTEMTABLETO{user}; ...
Your goals areto recognize the aspects of the EXPLAIN plan that indicate a query is optimizedwell, and to learn the SQL syntax and indexing techniques to improve the planif you see some inefficient operations. 查看执行计划示例: mysql>explain select * from user where User='root'; ...
root@127.0.0.1:26257/movr> \h EXPLAIN Command: EXPLAIN Description: show the logical plan of a query Category: miscellaneous Syntax: EXPLAIN <statement> EXPLAIN ([PLAN ,] <planoptions...> ) <statement> EXPLAIN (DISTSQL) <statement> EXPLAIN ANALYZE [(DISTSQL)] <statement> EXPLAIN ANALYZE (...
Microsoft SQL Server Vertica Explain Plan executes your query and records the plan that the database devises to execute it. By examining this plan, you can find out if the database is picking the right indexes and joining your tables in the most efficient manner. The explain plan feature wor...
The execution plan shows that DBMS parses the SQL commands.The 1st step is executing SELECT STATEMENT and the 2nd step is access EMP table using ‘FULL TABLE SCAN’. The statistics shows that historical statistics information of destinate data.It implies that method of getting physical data.For...