The EXPLAIN command will fail if you use it for other SQL commands, such as data definition language (DDL) or database operations.The EXPLAIN output relative unit costs are used by Amazon Redshift to choose a query plan. Amazon Redshift compares the sizes of various resource estimates to ...
1- at start of stmt, to set explain_info_for_others.lex/sql_command 2- at end of JOIN::optimize(), to set JOIN::plan 3- in JOIN::cleanup(true), to set JOIN::plan to NULL 4- at end of stmt, to reset explain_info_for_others.lex/sql_command Actually step 4 should be done i...
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...
These commands exist to help database administrators and developers understand how SQLite is processing SQL commands. They are designed for interactive tuning and adjustments. It is not recommended that applications programmatically query or utilize this data, as both the data and the format may change...
To see which AWS data source integrations support this SQL command, see Supported OpenSearch SQL commands and functions. The EXPLAIN statement is used to provide logical/physical plans for an input statement. By default, this clause provides information about a physical plan only. Syntax EXPLAIN...
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src/include/commands/explain.hsrc/backend/commands/explain.c/**执行计划输出结果的结构体*/typedef struct ExplainState{ StringInfo str; * output buffer */ * options */ bool verbose; * be verbose */ bool analyze; * print actual times */ bool costs; * print estimated costs */ bool buffers...
To find the minimum required privileges for a SQL statement, refer to theSQL reference documentationfor the statement. 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. ...
For example, run the commands inExample 9-2from a SQL*Plus session to create thePLAN_TABLEin theHRschema. Example 9-2 Creating a PLAN_TABLE CONNECT HR/your_password@$ORACLE_HOME/RDBMS/ADMIN/UTLXPLAN.SQLTable created. Oracle Corporation recommends that you drop and rebuild thePLAN_TABLEtable...
Using Permissions in the SQL Commander Sending Comments to the Database with Statements Using Client-Side Commands Parameterized SQL - Variables and Parameter Markers Working with Result Sets Working with Charts Exporting a Grid Comparing Data Monitoring Data Changes Accessing Frequently Used...