Note: some common check constraints can be configured via the community package you create indexes for a database table, consider how you will use the table. Multiple check constraints can be defined on the same table, each with their own name. ToTable(b => b.HasCheckConstraint('CK_Prices', ' > ')) You can use the Fluent API to specify a check constraint on a table, provided as a SQL expression: protected override void OnModelCreating(ModelBuilder modelBuilder) Check constraints are similar to non-null constraints (which prohibit nulls in a column) or to unique constraints (which prohibit duplicates), but allow arbitrary SQL expression to be defined. But in addition, queries accessing only the Title and PublishedOn columns will not need to access the table and will run more efficiently: protected override void OnModelCreating(ModelBuilder modelBuilder)Ĭheck constraints are a standard relational feature that allows you to define a condition that must hold for all rows in a table any attempt to insert or modify data that violates the constraint will fail.

In the following example, the Url column is part of the index key, so any query filtering on that column can use the index. For more information on SQL Server included columns, see the documentation. This can significantly improve query performance when all columns in the query are included in the index either as key or nonkey columns, as the table itself doesn't need to be accessed. Some relational databases allow you to configure a set of columns which get included in the index, but aren't part of its 'key'.

protected override void OnModelCreating(ModelBuilder modelBuilder) To override this convention you can supply a null value. When using the SQL Server provider EF adds an 'IS NOT NULL' filter for all nullable columns that are part of a unique index. You can use the Fluent API to specify a filter on an index, provided as a SQL expression: protected override void OnModelCreating(ModelBuilder modelBuilder)

For more information on SQL Server filtered indexes, see the documentation. This allows you to index only a subset of a column's values, reducing the index's size and improving both performance and disk space usage. Some relational databases allow you to specify a filtered or partial index. Protected override void OnModelCreating(ModelBuilder modelBuilder)

Indexes