10 things in SQL Server (which don’t work as expected) Comments enabled. I *really* need your comment 10. Unique NULL When declaring UNIQUE constraints on columns, SQL Server treats all NULL values as unique. This means you can't have more than one NULL value in a unique column. ...
Sequential ScanscanAmazon Redshift relation scan or table scan operator or step. Scans whole table sequentially from beginning to end; also evaluates query constraints for every row (Filter) if specified with WHERE clause. Also used to run INSERT, UPDATE, and DELETE statements. ...
One row is inserted into the PLAN_TABLE for each step used in executingexplainable-sql-statement. The steps for enforcing referential constraints are not included. If a statement table exists, one row that provides a cost estimate of processing the explainable statement is inserted into the stateme...
Allows a large table to be broken up into a number of smaller partitions which can be queried much more quickly than the table as a whole a union all view is built over the top to provide the original functionality Check constraints or where clauses provide partition elimination capabilities ...
很显然这条SQL是从里向外的执行,就是从id=3 向上执行. 2. select_type 就是select类型,可以有以下几种 (1) SIMPLE 简单SELECT(不使用UNION或子查询等) 例如: mysql> explain select * from t3 where id=3952602; +---+---+---+---+---+---+---+---+---+---+ | id | select_type |...
investing in savings so there would be an extra row added beneath and a formula would be in D5. Lots of formulas. Normally I run that out for 5 weeks. So when one week is done, I move the tab to the back and recreate all the formulas 5 weeks in advance. Starting to see my ...
The population of the Explain tables by the Explain facility will not activate triggers or referential or check constraints. For example, if an insert trigger were defined on the EXPLAIN_INSTANCE table, and an eligible statement were explained, the trigger would not be activated. ...
> > The exact rule is that equality constraints on leading columns, > > > plus any inequality constraints on the first column that does > > > not have an equality constraint, will be used to limit the portion > > > of the index that is scanned. ...
QSM-01052 referential integrity constraint on table, string, not VALID in ENFORCED integrity mode Cause: A join present in the materialized view requires validated primary/foreign key constraints in ENFORCED query rewrite integrity mode. Action: Validate the constraint or change the integrity mode with...
/generate-constraints Matrix: Static checks, mypy, docs / MyPy checks Waiting for pending jobs Matrix: Integration Tests / tests-integration Waiting for pending jobs Matrix: MySQL tests / tests Waiting for pending jobs Matrix: Non-DB tests / tests ...