How to do a union across multiple instances of SQL Server?

How to do a union across multiple instances of SQL Server?

How to do a union across multiple instances of Sql Server? I have two Sql Servers (two distinct databases, (i.e. two machines)) with the same structure. Is there a way to do a SELECT * FROM (SELECT * FROM TableOnServerA Union SELECT * FROM TableOnServerB)?

How does paging by row number work in SQL Server?

Paging by row number in SQL Server always works by enumerating rows start to end until the desired window is reached. Whether the rows are drawn from a table or from multiple merged tables does not make a fundamental difference. So a good chance to make this fast is to create a covering index keyed on col1.

Do you select from all 5 tables in pagination?

Since the tables are ordered in the result set for the paging (Union ALL does not sort), there is no reason to select from all 5 tables. You should change the code to :

When to use Union all for multiple tables?

If (col1, col2) is not globally unique across your tmpTable, you may need to add another column to the query and to the WHERE and ORDER BY clause to avoid losing records between pages. With the above method, you cannot immediately jump to page 3 without having first fetched the previous 40 records.

When to use Union in multiple table queries?

Use the UNION operator to combine the results of two or more SELECT statements to generate a single result set. The syntax for using UNION is as follows: The statements combined must have the same number of columns and compatible data types. The column names from the first statement are used as headings for the result set.

Since the tables are ordered in the result set for the paging (Union ALL does not sort), there is no reason to select from all 5 tables. You should change the code to :

What’s the difference between SQL UNION and Union all?

The SQL Union All operator combines the result of two or more Select statement similar to a SQL Union operator with a difference. The only difference is that it does not remove any duplicate rows from the output of the Select statement. Let us rerun the previous examples with SQL Union All operator.

Paging by row number in SQL Server always works by enumerating rows start to end until the desired window is reached. Whether the rows are drawn from a table or from multiple merged tables does not make a fundamental difference. So a good chance to make this fast is to create a covering index keyed on col1.