2,000 might be a real performance hit and definitely 20,000. For one thing, MySQL runs on various operating systems. But first, you need to narrow the problem down to MySQL. Duplicating data in multiple columns instead of setting up other tables and relating the data through foreign keys or interim tables can cause a performance issue. In case of many variable length columns on the table, the column order may affect the performance of the queries. One row: represents a database (schema) Scope of rows: all databases (schemas) Ordered by: database_name; Sample results If we don't have an index on the column it would have to do a table scan in both cases and we would not see any difference in pe… число столбцов в избранном Влияет ли производительность запросов? How much does the architecture of data affect the speed of a query. Там не будет никакой разницы в производительности на основе позиции столбца. columns - total number of columns in a database (schema) tables - number of tables in a database (schema) average_column_count - average number of columns in a table in a database (schema) Rows. Solution Does the number of fields in a table affect performance even if not referenced? For another, there are a variety of storage engines and file formats—each with their own nuances. Там будет разница в производительности, однако 99% времени, вы не заметили - как правило, вы даже не будете в состоянии обнаружить его! 1.000 is just an example, based on your server resources you could increase or decrease this number. Feel free to ask questions and write me. For large number of columns dynamic rows become very expensive and you have to watch out. The order of columns in your where clause shouldn't really matter, since MySQL will optimize the query before executing it. One of the varchar columns will have the collation set to SQL_Latin1_General_CP1_CI_AS and the other will have the collation set to SQL_Latin1_General_CP1_CS_AS. In order to carry out this small test we will create a simple 3 column table with an integer primary key column as well as two varchar columns. Many a times people find that they create index but the query is still slow or the index is not being used by MySQL to fetch the result-set. In terms of the original question any large table will have performance implications but in general it's better to have one large table rather than a number of smaller ones. I need to have one table with 500 000 to 1 000 000 rows. Существует также вторичная выгода в возвращении меньше столбцов из SELECT, так как это сводит к минимуму нагрузки ввода / вывода, особенно если есть медленная сеть между сервером базы данных и приложением , потребляющим данные - т.е. An interesting question is a pleasure to answer, and I really enjoy receiving feedback, The Journalist template by Lucian E. Marin — Built for WordPress. does the depth of the prototype chain for an object affect the performance? CASE 1: I have a table with 30 columns and I query using 4 columns in the where clause. The client IP address is used instead. Это, как говорится, это всегда полезно / benificial вернуться в несколько столбцов, как это возможно, чтобы удовлетворить ваши потребности. Multiple Left Joins in MS Access using sub-queries. In the scenario you describe, you state that the most commonly used fields in the table are the primary key (CompanyId), a single data field (CompanyName), and a foreign key (IndustryId). Where are my Visual Studio Android emulators? Кроме того, это также , вероятно , что ваш запрос будет работать против индекса , а не таблицы в любом случае, и поэтому с индексами точно такой же размер изменение может быть 0 . не будет столь же хорошо , как индекс покрытия. Uncaught TypeError: $(…).code is not a function (Summernote), Monitor incoming IP connections in Amazon AWS, Scala Class body or primary constructor body, Best practice for updating individual state properties with Redux Saga, Yii2: How add a symbol before and after an input field. Теперь строительство стола другая история, например, количество строк, индексов, количество колонок и т.д. Oracle will first determine which rows satisfy your query. Why does the number of