With the help ofEXPLAIN, you can see where you should add indexes to tables so that thestatement executes faster by using indexes to find rows. You can also useEXPLAIN to check whether the optimizer joins the t
unionM,N: The row refers to the union of the rows with id values of M and N. derivedN: The row refers to the derived table result for the row with an id value of N. A derived table may result, for example, from a subquery in the FROM clause. subqueryN: The row refers to the...
We recommend that you prevent non-equivalent joins in SQL statements. The following code provides an example of a nested loop join. BEGIN; CREATE TABLE public.nestedloop_test_1 ( a integer not null, b integer not null ); CALL set_table_property('public.nestedloop_test_1', 'distribution_...
Examples {{< copyable "sql" >}} CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, c1 INT NOT NULL); Query OK, 0 rows affected (0.12 sec) {{< copyable "sql" >}} INSERT INTO t1 (c1) VALUES (1), (2), (3); Query OK, 3 rows affected (0...
in the second table, the third table, and so on. When all tables areprocessed, MySQL outputs the selected columns and backtracks through the tablelist until a table is found for which there are more matching rows. The nextrow is read from this table and the process continues with the ...
Examples Note For these examples, the sample output might vary depending on Amazon Redshift configuration. The following example returns the query plan for a query that selects the EVENTID, EVENTNAME, VENUEID, and VENUENAME from the EVENT and VENUE tables: ...
This tableis referenced as the child of table in a join that can be pushed down to the NDBkernel. Applies only in MySQL Cluster, when pushed-down joins are enabled. Seethe description of the ndb_join_pushdown serversystem variable for more information and examples. ...
(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_...
In this case, the statement displays information only for the named column. wild, if given, is a pattern string. It can contain the SQL % and _ wildcard characters. In this case, the statement displays output only for the columns with names matching the string. There is no need to ...
Given below are the examples to see the implementation of the EXPLAIN command with SQL queries: Example #1 We will firstly consider the query statement in SQL which will retrieve the values of the columns named Article_id and Article_name from Educba_articles table and the information of writer...