As of 5.7.3 / MariaDB 10.1, some forms of UNION deliver the. Useful for complex queries that you want to make sure are not taking too long to execute. UNION always involves a temp table to collect the results. The error contains information about the query, bindings, and the timeout that was set. Basically, performance wise, you have to use LIMIT on each query involved into UNION, if you know there will be no duplicates between result sets you should. If you dont specify ALL or DISTINCT, it will depend on the uniondefaultmode. Sets a timeout for the query and will throw a TimeoutError if the timeout is exceeded. You can use UNION with explicitly specifying UNION ALL or UNION DISTINCT. 1, the server can in most cases execute UNION ALL without creating a temporary table, improving performance (see MDEV-334). Suppose it is desired that UNION operation should return not more than 3 rows. If you don't want to manually specify the result type, it is recommended to always use the type of last value of the chain and assign result of any future chain continuation to a separate variable (which will have a different type). So my questions are, doesn't UNION and LIMIT play well together? And does anyone have a clever workaround, or an alternative solution/setup for this? If anyone is willing to help out, i can provide you with more details if needed.Knex ( 'users' ). In large tables with thousands or millions of data rows, it takes some time to. I guess this occurs after php reaches its timeout. La commande UNION de SQL permet de mettre bout-bout les rsultats de plusieurs requtes utilisant elles-mme la commande SELECT. MySQL has long supported UNION MySQL 8.0 adds support for INTERSECT and EXCEPT (MySQL 8.0.31 and later). The LIMIT or TOP clause is useful to specify the number of data rows to return. However, if i change offset to something above 0, which is needed for the page to be paginated, the page is loading forever and eventually ends up with an almost never-ending loop, with a php notice saying 'undefined offset' for each iteration. This works just fine as long as I display it in one long list, or use 0 as offset in the LIMIT. mysql request limit union counter Share Improve this question Follow asked at 23:41 Baylock 1,236 4 25 49 1 Your are just using LIMIT wrong LIMIT does not take from row and to row as parameters, but an offset (that’s from row, ok), and a row count that’s the number of rows you want. The reason I use UNION is that the tables don't have the same columns, but I need the data to be presented together in a chronological order.
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