1 Child of 'table' pushed join@1 此值只会在NDB Cluster下出现。 2 const row not found 例如查询语句SELECT ... FROM tbl_name,而表是空的 3 Deleting all rows 对于DELETE语句,某些引擎(例如MyISAM)支持以一种简单而快速的方式删除所有的数据,如果使用了这种优化,则显示此
圆脚框--group/sort,分组或排序 钻石框--joins Framed boxes(有外框)--子查询。 Join type连接类型: https://dev.mysql.com/doc/refman/8.0/en/explain-output.html#explain-join-types 力扣550例子 CreatetableIfNotExistsActivity (player_idint, device_idint, event_date date, games_playedint)Truncatetab...
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. const row not found (JSON...
EXPLAIN returnsa row of information for each table used in the SELECT statement. It lists thetables in the output in the order that MySQL would read them while processingthe statement. MySQL resolves all joins using a nested-loop join method. Thismeans that MySQL reads a row from the first ...
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_...
Understand Complex SQL Queries Easily using AI Expert SQL Query Write down your SQL Query in the following box and select target datbase. Once done, click onExplain CodeButton to generate the explanation of your SQL query. SELECT U.userid, U.fullname, U.emailid, U.state, U.country, U....
There are two types of predicates: ACCESS and FILTER. The ACCESS predicates for an index are used to fetch the relevant blocks by applying search criteria to the appropriate columns. The FILTER predicates are evaluated after the blocks have been fetched. ALL Includes the information shown ...
backoff: Contains different types of backoff and the total waiting time of backoff. Insert The execution information of an Insert operator is typically as follows: prepare:109.616µs, check_insert:{total_time:1.431678ms, mem_insert_time:667.878µs, prefetch:763.8µ...
Joins can be categorized by join type and by distribution type. Join types Join types define the way in which the join operation occurs. CrossJoin –Produces the Cartesian product of the two tables joined. InnerJoin –Selects records that have matching values in both tables. LeftJoin –Select...
EXPLAIN returnsa row of information for each table used in the SELECT statement. It lists thetables in the output in the order that MySQL would read them while processingthe statement. MySQL resolves all joins using a nested-loop join method. Thismeans that MySQL reads a row from the first...