Table of Contents

Class LinqOptions

Namespace
LinqToDB
Assembly
linq2db.dll
public sealed record LinqOptions : IOptionSet, IConfigurationID, IEquatable<LinqOptions>
Inheritance
LinqOptions
Implements
Extension Methods

Constructors

LinqOptions() 

public LinqOptions()

LinqOptions(bool, bool, bool, bool, bool, bool, bool, bool, bool, TimeSpan?, bool, bool, bool, bool, bool) 

public LinqOptions(bool PreloadGroups = false, bool IgnoreEmptyUpdate = false, bool GenerateExpressionTest = false, bool TraceMapperExpression = false, bool DoNotClearOrderBys = false, bool OptimizeJoins = true, bool CompareNullsAsValues = true, bool GuardGrouping = true, bool DisableQueryCache = false, TimeSpan? CacheSlidingExpiration = null, bool PreferApply = true, bool KeepDistinctOrdered = true, bool ParameterizeTakeSkip = true, bool EnableContextSchemaEdit = false, bool PreferExistsForScalar = false)

Parameters

PreloadGroups bool

Controls how group data for LINQ queries ended with GroupBy will be loaded:

  • if true - group data will be loaded together with main query, resulting in 1 + N queries, where N - number of groups;
  • if false - group data will be loaded when you call enumerator for specific group IGrouping<TKey, TElement>. Default value: false.
IgnoreEmptyUpdate bool

Controls behavior of linq2db when there is no updateable fields in Update query:

  • if true - query not executed and Update operation returns 0 as number of affected records;
  • if false - LinqException will be thrown. Default value: false.
GenerateExpressionTest bool

Enables generation of test class for each LINQ query, executed while this option is enabled. This option could be useful for issue reporting, when you need to provide reproducible case. Test file will be placed to linq2db subfolder of temp folder and exact file path will be logged to data connection tracing infrastructure. See TraceSwitch for more details. Default value: false.

TraceMapperExpression bool

Enables logging of generated mapping expression to data connection tracing infrastructure. See TraceSwitch for more details. Default value: false.

DoNotClearOrderBys bool

Controls behavior, when LINQ query chain contains multiple OrderBy<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) or OrderByDescending<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) calls:

  • if true - non-first OrderBy* call will be treated as ThenBy* call;
  • if false - OrderBy* call will discard sort specifications, added by previous OrderBy* and ThenBy* calls. Default value: false.
OptimizeJoins bool

If enabled, linq2db will try to reduce number of generated SQL JOINs for LINQ query. Attempted optimizations:

  • removes duplicate joins by unique target table key;
  • removes self-joins by unique key;
  • removes left joins if joined table is not used in query. Default value: true.
CompareNullsAsValues bool
If set to true nullable fields would be checked for IS NULL in Equal/NotEqual comparisons. This affects: Equal, NotEqual, Not Contains Default value: true. 
public class MyEntity
  {
      public int? Value;
  }

db.MyEntity.Where(e => e.Value != 10)


from e1 in db.MyEntity
join e2 in db.MyEntity on e1.Value equals e2.Value
select e1


var filter = new [] {1, 2, 3};
db.MyEntity.Where(e => ! filter.Contains(e.Value))

Would be converted to next queries:

SELECT Value FROM MyEntity WHERE Value IS NULL OR Value != 10

 SELECT e1.Value
 FROM MyEntity e1
 INNER JOIN MyEntity e2 ON e1.Value = e2.Value OR (e1.Value IS NULL AND e2.Value IS NULL)

 SELECT Value FROM MyEntity WHERE Value IS NULL OR NOT Value IN (1, 2, 3)
GuardGrouping bool
Controls behavior of LINQ query, which ends with GroupBy call. - if true - LinqToDBException will be thrown for such queries; - if false - behavior is controlled by PreloadGroups option. Default value: true. More details.
DisableQueryCache bool
Used to disable LINQ expressions caching for queries. This cache reduces time, required for query parsing but have several side-effects:

- cached LINQ expressions could contain references to external objects as parameters, which could lead to memory leaks if those objects are not used anymore by other code

- cache access synchronization could lead to bigger latencies than it saves.

Default value: false.

It is not recommended to enable this option as it could lead to severe slowdown. Better approach will be to call ClearCache() method to cleanup cache after queries, that produce severe memory leaks you need to fix.

More details.
CacheSlidingExpiration TimeSpan?

Specifies timeout when query will be evicted from cache since last execution of query. Default value is 1 hour.

PreferApply bool

Used to generate CROSS APPLY or OUTER APPLY if possible. Default value: true.

KeepDistinctOrdered bool

Allows SQL generation to automatically transform

SELECT DISTINCT value FROM Table ORDER BY date

Into GROUP BY equivalent if syntax is not supported Default value: true.

ParameterizeTakeSkip bool

Enables Take/Skip parameterization. Default value: true.

EnableContextSchemaEdit bool

If true, user could add new mappings to context mapping schems (MappingSchema). Otherwise, LinqToDBException will be generated on locked mapping schema edit attempt. It is not recommended to enable this option as it has performance implications. Proper approach is to create single MappingSchema instance once, configure mappings for it and use this MappingSchema instance for all context instances. Default value: false.

PreferExistsForScalar bool

If true, EXISTS operator will be generated instead of IN operator for scalar values.

SELECT Value FROM MyEntity e WHERE EXISTS(SELECT * FROM MyEntity2 e2 WHERE e2.Value = e.Value)

vs

SELECT Value FROM MyEntity e WHERE Value IN (SELECT Value FROM MyEntity2 e2)

Default value: false.

Properties

CacheSlidingExpiration

Specifies timeout when query will be evicted from cache since last execution of query. Default value is 1 hour.

public TimeSpan? CacheSlidingExpiration { get; init; }

Property Value

TimeSpan?

CacheSlidingExpirationOrDefault 

public TimeSpan CacheSlidingExpirationOrDefault { get; }

Property Value

TimeSpan

CompareNullsAsValues

If set to true nullable fields would be checked for IS NULL in Equal/NotEqual comparisons. This affects: Equal, NotEqual, Not Contains Default value: true. 
public class MyEntity
  {
      public int? Value;
  }

db.MyEntity.Where(e => e.Value != 10)


from e1 in db.MyEntity
join e2 in db.MyEntity on e1.Value equals e2.Value
select e1


var filter = new [] {1, 2, 3};
db.MyEntity.Where(e => ! filter.Contains(e.Value))

Would be converted to next queries:

SELECT Value FROM MyEntity WHERE Value IS NULL OR Value != 10

 SELECT e1.Value
 FROM MyEntity e1
 INNER JOIN MyEntity e2 ON e1.Value = e2.Value OR (e1.Value IS NULL AND e2.Value IS NULL)

 SELECT Value FROM MyEntity WHERE Value IS NULL OR NOT Value IN (1, 2, 3)
 
public bool CompareNullsAsValues { get; init; }

Property Value

bool

DisableQueryCache

Used to disable LINQ expressions caching for queries. This cache reduces time, required for query parsing but have several side-effects:

- cached LINQ expressions could contain references to external objects as parameters, which could lead to memory leaks if those objects are not used anymore by other code

- cache access synchronization could lead to bigger latencies than it saves.

Default value: false.

It is not recommended to enable this option as it could lead to severe slowdown. Better approach will be to call ClearCache() method to cleanup cache after queries, that produce severe memory leaks you need to fix.

More details. 
public bool DisableQueryCache { get; init; }

Property Value

bool

DoNotClearOrderBys

Controls behavior, when LINQ query chain contains multiple OrderBy<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) or OrderByDescending<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) calls:

  • if true - non-first OrderBy* call will be treated as ThenBy* call;
  • if false - OrderBy* call will discard sort specifications, added by previous OrderBy* and ThenBy* calls. Default value: false.
public bool DoNotClearOrderBys { get; init; }

Property Value

bool

EnableContextSchemaEdit

If true, user could add new mappings to context mapping schems (MappingSchema). Otherwise, LinqToDBException will be generated on locked mapping schema edit attempt. It is not recommended to enable this option as it has performance implications. Proper approach is to create single MappingSchema instance once, configure mappings for it and use this MappingSchema instance for all context instances. Default value: false.

public bool EnableContextSchemaEdit { get; init; }

Property Value

bool

GenerateExpressionTest

Enables generation of test class for each LINQ query, executed while this option is enabled. This option could be useful for issue reporting, when you need to provide reproducible case. Test file will be placed to linq2db subfolder of temp folder and exact file path will be logged to data connection tracing infrastructure. See TraceSwitch for more details. Default value: false.

public bool GenerateExpressionTest { get; init; }

Property Value

bool

GuardGrouping

Controls behavior of LINQ query, which ends with GroupBy call. - if true - LinqToDBException will be thrown for such queries; - if false - behavior is controlled by PreloadGroups option. Default value: true. More details. 
public bool GuardGrouping { get; init; }

Property Value

bool

IgnoreEmptyUpdate

Controls behavior of linq2db when there is no updateable fields in Update query:

  • if true - query not executed and Update operation returns 0 as number of affected records;
  • if false - LinqException will be thrown. Default value: false.
public bool IgnoreEmptyUpdate { get; init; }

Property Value

bool

KeepDistinctOrdered

Allows SQL generation to automatically transform

SELECT DISTINCT value FROM Table ORDER BY date

Into GROUP BY equivalent if syntax is not supported Default value: true.

public bool KeepDistinctOrdered { get; init; }

Property Value

bool

OptimizeJoins

If enabled, linq2db will try to reduce number of generated SQL JOINs for LINQ query. Attempted optimizations:

  • removes duplicate joins by unique target table key;
  • removes self-joins by unique key;
  • removes left joins if joined table is not used in query. Default value: true.
public bool OptimizeJoins { get; init; }

Property Value

bool

ParameterizeTakeSkip

Enables Take/Skip parameterization. Default value: true.

public bool ParameterizeTakeSkip { get; init; }

Property Value

bool

PreferApply

Used to generate CROSS APPLY or OUTER APPLY if possible. Default value: true.

public bool PreferApply { get; init; }

Property Value

bool

PreferExistsForScalar

If true, EXISTS operator will be generated instead of IN operator for scalar values.

SELECT Value FROM MyEntity e WHERE EXISTS(SELECT * FROM MyEntity2 e2 WHERE e2.Value = e.Value)

vs

SELECT Value FROM MyEntity e WHERE Value IN (SELECT Value FROM MyEntity2 e2)

Default value: false.

public bool PreferExistsForScalar { get; init; }

Property Value

bool

PreloadGroups

Controls how group data for LINQ queries ended with GroupBy will be loaded:

  • if true - group data will be loaded together with main query, resulting in 1 + N queries, where N - number of groups;
  • if false - group data will be loaded when you call enumerator for specific group IGrouping<TKey, TElement>. Default value: false.
public bool PreloadGroups { get; init; }

Property Value

bool

TraceMapperExpression

Enables logging of generated mapping expression to data connection tracing infrastructure. See TraceSwitch for more details. Default value: false.

public bool TraceMapperExpression { get; init; }

Property Value

bool

Methods

Equals(LinqOptions?)

Indicates whether the current object is equal to another object of the same type.

public bool Equals(LinqOptions? other)

Parameters

other LinqOptions

An object to compare with this object.

Returns

bool

true if the current object is equal to the other parameter; otherwise, false.

GetHashCode()

Serves as a hash function for a particular type.

public override int GetHashCode()

Returns

int

A hash code for the current object.