SQL Server: Support for full-text search TVFs (CONTAINSTABLE/FREETEXTTABLE) by Abde1rahman1 · Pull Request #37489 · dotnet/efcore

Abde1rahman1 · 2026-01-12T17:56:23Z

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Description

This PR implements support for SQL Server Full-Text Search Table-Valued Functions: CONTAINSTABLE and FREETEXTTABLE.

Currently, EF Core only supports scalar Full-Text functions (CONTAINS and FREETEXT). This PR bridges the gap by allowing users to treat Full-Text results as queryable sources, enabling access to the Rank column and allowing for efficient Joins between full-text results and entity tables.

Key Architectural Changes

AST Node Definition: Introduced FullTextTableExpression (inheriting from TableExpressionBase) to represent the TVF in the relational command tree.
Query Translation: Extended SqlServerQueryableMethodTranslatingExpressionVisitor to intercept ContainsTable and FreeTextTable method calls.
- Constructed a SelectExpression wrapped in a ShapedQueryExpression.
- Implemented manual projection mapping for [Key] and [Rank] columns.
- Leveraged SqlAliasManager for dynamic table alias generation.
Result Shaping: Implemented a custom ShaperExpression using Expression.New to bind SQL result columns to the FullTextTableResult DTO.
SQL Generation: Added VisitFullTextTable in SqlServerQuerySqlGenerator to handle the specific TVF syntax requirements in SQL Server.

Example Usage

var query = from p in context.Products
            join ct in EF.Functions.ContainsTable(context.Products.Select(x => x.Name), "search_term")
            on p.Id equals (int)ct.Key
            orderby ct.Rank descending
            select new { p.Name, ct.Rank };

Related Issue

Fixes #11487

Tests for the changes have been added (for bug fixes / features)
Code follows the same patterns and style as existing code in this repo

roji

Thanks for submitting this PR - it's a good start but requires quite a lot of work. Translating a specialized TVF like this is quite challenging, and requires quite a bit of EF internals knowledge (it's not a good issue for a casual external contributor).

Unless you're wililng to invest significant time here and go into complicated internal architecture (just using AI here probably won't be sufficient) please let me know - I'm OK to take this over and complete it (and you can be happy with the work you've done here!).

Otherwise, see first round of comments below.

roji · 2026-01-12T19:25:04Z

src/EFCore.SqlServer/Extensions/SqlServerDbFunctionsExtensions.cs

Move these to SqlServerQueryableExtensions, similar to RelationalQueryableExtensions.

roji · 2026-01-12T19:26:04Z

src/EFCore.SqlServer/Extensions/SqlServerDbFunctionsExtensions.cs

Is this intentionally object as opposed to string? Is there a reason for that?

Also, is it possible for the full-text search column to be nullable? If so this parameter needs to be nullable too.

Regarding the object type: I used object to stay consistent with other full-text extensions like SqlServerDbFunctionsExtensions.Contains, which takes an object property to allow the expression tree to capture the property access before it's translated. However, if the convention for Table-Valued Functions in EF Core prefers a specific type like string, I’m happy to change it.

Regarding nullability: Yes, full-text search columns can be nullable in SQL Server. I will update the parameter to be object? (or string?) to correctly reflect the provider's capabilities and avoid any potential issues with nullable properties

roji · 2026-01-12T20:07:53Z

src/EFCore.SqlServer/Extensions/SqlServerDbFunctionsExtensions.cs

It isn't ideal for this to be an untyped object, but I can't really see a way for this to be generic over the key type... The key column is determined in the CREATE FULLTEXT INDEX DDL, and we have no way of flowing that as a generic parameter here.

I'm thinking it might be a good idea to accept the key type as a generic type parameter to the FreeTextTable/ContainsTable methods; another alternative is to accept an additional parameter on the functions where the user selects the key property - that would allow us to flow that type to the return type, but it would be a bit silly (if the user specifies anything other than the key property from CREATE FULLTEXT INDEX, the call fails).

Any thoughts on this?

I think the Generic approach (ContainsTable<TKey>) is the best way to go.

It’s simple and explicit. The user knows their database schema best, so they can just provide the correct type for the Key. This also keeps the translation logic clean and avoids the extra work of trying to infer the type from other properties.

If you're okay with this, I will update the code to use <TKey> and make FullTextTableResult generic

roji · 2026-01-12T20:16:12Z

src/EFCore.SqlServer/Query/Internal/SqlExpressions/FullTextTableExpression.cs

Why introduce a new expression type? Is TableValuedFunctionExpression not suitable somehow?

The reason I didn't use TableValuedFunctionExpression is that its Print method calls VisitCollection(Arguments). This treats all arguments as standard SqlExpression nodes, which the ExpressionPrinter translates into SQL literals (quoted strings) or parameters.

For CONTAINSTABLE, the first two arguments must be raw identifiers (Table and Column). By using a custom expression, I can bypass the standard Visit logic and use expressionPrinter.Append(Column.TableAlias) to print the table name directly without quotes, ensuring the SQL is syntactically correct for SQL Server

We shouldn't need a whole new expression type for this. We should be able to use TableValuedFunctionExpression, with the first two arguments (the table and column names) just being SqlFragmentExpressions. We'd still need special handling in SqlServerQuerySqlGenerator to quote those names, but at least we wouldn't have an additional expression type.

test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerTest.cs

roji · 2026-01-12T20:42:29Z

src/EFCore.SqlServer/Query/Internal/SqlServerQuerySqlGenerator.cs

Note that the first argument to these functions can only be a literal table name - not a table alias. For example, the following does not work:

SELECT * FROM Flags AS f WHERE ( SELECT TOP(1) RANK FROM CONTAINSTABLE (f, FlagColors, 'Green or Black') ORDER BY RANK DESC) <> 0;

Where replacing f with a table name (Flags) does:

SELECT * FROM Flags AS f WHERE ( SELECT TOP(1) RANK FROM CONTAINSTABLE (Flags, FlagColors, 'Green or Black') ORDER BY RANK DESC) <> 0;

We can use SqlFragmentExpression to represent the table and column names.

Thank you for the clarification. You're right, CONTAINSTABLE requires the actual table name rather than the alias.

I will refactor the implementation to use SqlFragmentExpression for both the table and column names. This ensures they are treated as raw SQL fragments and bypasses the quoting issues we discussed. I'll also make sure to pull the base table name from the metadata instead of using the alias

roji · 2026-01-12T20:45:49Z

test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerTest.cs

Requiring invokers to do ctx.Set<T>().Select() to get the property like this is problematic:

It isn't a good dev experience.

If the user diverges from this pattern in any way (e.g. projecting something other than a simple property), this will fail.

What happens if there's a Where before the Select? I think your code above would just ignore that (I may be wrong). In any case, these functions do not support pre-filtering or any other operator - they accept a literal table name as the source only.

To avoid all the above problems, we should instead try to make ContainsTable an extension method over DbSet; its source (first argument) would thus represent the table, and it would accept a lambda selector for the full-text property to be searched (and of course, the actual text to be searched):

var query = from c in ctx.Set<Customer>() join ct in ctx.Set<Customer>().ContainsTable(c => c.ContactName, "John") ....

Makes sense?

Sure. I’ll refactor the implementation to move ContainsTable and FreeTextTable as extension methods over IQueryable<TEntity> and update the visitor to handle this new pattern

roji · 2026-01-12T20:46:50Z

test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerTest.cs

Please move tests to NorthwindDbFunctionsQuerySqlServerTest alongside the existing full-text search tests (unless there's a specific reason not to).

I will move them

roji · 2026-01-12T20:48:02Z

test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerTest.cs

We need a lot more testing here - one simple test isn't enough.

Abde1rahman1 · 2026-01-12T21:46:33Z

Thanks for your reply and for the feedback. I am definitely willing to invest the necessary time to work on this feature and dive deeper into the EF Core internal architecture. I'd be honored to learn from your expertise throughout this process.

If you're available to provide guidance or point me in the right direction, I would be happy to put in the work and collaborate to get this implemented correctly.

…est.cs Co-authored-by: Shay Rojansky <roji@roji.org>

… extensions

…into feature-TVFs

Abde1rahman1 · 2026-01-13T00:27:45Z

Hi @roji
I have updated the PR to address your feedback. Here is a summary of the changes:

API Design: Moved ContainsTable and FreeTextTable to SqlServerQueryableExtensions. They are now extension methods over IQueryable using lambda property selectors for a better developer experience.
SQL Correctness: Updated the visitor to use actual table names (literals) instead of aliases, ensuring compatibility with SQL Server's requirements.
SqlFragmentExpression: Applied SqlFragmentExpression with proper identifier delimiting for both table and column names.
Generic TKey: Refactored the result type to FullTextTableResult to support different primary key types dynamically.
Cleanup: Removed redundant ClearServiceProviderCache wrappers and moved functional tests to NorthwindDbFunctionsQuerySqlServerTest.

roji

Here are some more comments.

Please ensure that all tests pass before requesting another review.

roji · 2026-01-13T06:03:20Z

src/EFCore.SqlServer/Extensions/SqlServerQueryableExtensions.cs

+    /// <param name="propertySelector">A lambda expression selecting the property to search.</param>
+    /// <param name="searchCondition">The search condition.</param>
+    /// <returns>The table-valued function result containing Key and Rank columns.</returns>
+    public static IQueryable<FullTextTableResult<TKey>> ContainsTable<TEntity, TKey>(


Note that the two SQL Server functions accept two additional parameters: language and top_n_by_rank.

roji · 2026-01-13T06:05:29Z

src/EFCore.SqlServer/Extensions/SqlServerQueryableExtensions.cs

nit: use primary constructor

roji · 2026-01-13T06:07:39Z

src/EFCore.SqlServer/Extensions/SqlServerQueryableExtensions.cs

Make this a readonly struct, as it's a very think wrapper that can be immutable.

roji · 2026-01-13T06:10:31Z

src/EFCore.SqlServer/Query/Internal/SqlExpressions/FullTextTableExpression.cs

We shouldn't need a whole new expression type for this. We should be able to use TableValuedFunctionExpression, with the first two arguments (the table and column names) just being SqlFragmentExpressions. We'd still need special handling in SqlServerQuerySqlGenerator to quote those names, but at least we wouldn't have an additional expression type.

roji · 2026-01-13T06:11:06Z

test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerTest.cs

roji · 2026-01-13T06:24:25Z

src/EFCore.SqlServer/Query/Internal/SqlServerQueryableMethodTranslatingExpressionVisitor.cs

Do not call MakeGenericType, as it's incompatible with NativeAOT, which we're starting to move towards. You should already have the correct return type on the method in the inputted MethodCallExpression.

roji · 2026-01-13T06:25:30Z

src/EFCore.SqlServer/Query/Internal/SqlServerQueryableMethodTranslatingExpressionVisitor.cs

Call the columns KEY and RANK (uppercase) as per the documentation.

roji · 2026-01-13T06:25:59Z

src/EFCore.SqlServer/Query/Internal/SqlServerQueryableMethodTranslatingExpressionVisitor.cs

Suggested change

var alias = _queryCompilationContext.SqlAliasManager.GenerateTableAlias("ft");

var alias = _queryCompilationContext.SqlAliasManager.GenerateTableAlias("fts");

roji · 2026-01-13T06:34:42Z

src/EFCore.SqlServer/Query/Internal/SqlServerQueryableMethodTranslatingExpressionVisitor.cs

This is wrong - the select projects out both the key and the column; down below you're also mixing two projection type (this is a complicated and messy part of SelectExpression currently). Instantiate a SelectExpression without any projections, then call ReplaceProjection() with a dictionary argument to provide the two projections.

roji · 2026-01-13T06:34:55Z

test/EFCore.SqlServer.FunctionalTests/Query/NorthwindDbFunctionsQuerySqlServerTest.cs

Abde1rahman1 · 2026-01-17T10:09:16Z

"Hi @roji ,
I've addressed all your comments. However, the tests are still failing because SqlServerQueryableMethodTranslatingExpressionVisitor.VisitMethodCall is not being triggered for the new method. It seems the translation isn't picking up the method call as expected. Could you please provide some guidance on why the visitor might be bypassing it ?

roji · 2026-01-20T09:13:42Z

@Abde1rahman1 I've just submitted #37536, implementing support for the SQL Server [VECTOR_SEARCH()](VECTOR_SEARCH (Transact-SQL) - SQL Server _ Microsoft Learn) function, which is quite similar to the full-text search functions which you're working on here. Please take a look at that PR; it should help you with you trouble around VisitMethodCall, and in general, please align your implementation to what you see there.

roji · 2026-01-28T17:54:29Z

@Abde1rahman1 as I haven't heard back from you, and as there was still considerably (and tricky) work remaining here, I went ahead and submitted #37578, which implements this.

Thanks again for working on this!

Abde1rahman1 · 2026-01-28T18:02:15Z

Hi @roji, I’m really sorry for the late response. I’ve been quite busy with some work commitments lately and couldn't give this the focus it deserved. I’m glad you moved forward with it, and I’ll definitely check out your PR to learn from your implementation. My schedule is much clearer now, so please let me know if there are any remaining tasks or other issues I can help with. I’d love to stay involved! Thanks for the opportunity

Abde1rahman1 requested a review from a team as a code owner January 12, 2026 17:56

Add CONTAINSTABLE and FREETEXTTABLE support for SQL Server

9785ec0

Abde1rahman1 force-pushed the feature-TVFs branch from 235a837 to 9785ec0 Compare January 12, 2026 18:31

AndriySvyryd added the community-contribution label Jan 12, 2026

AndriySvyryd assigned roji Jan 12, 2026

roji requested changes Jan 12, 2026

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roji changed the title ~~SQL Server: Support for Full-Text Search Table-Valued Functions (CONTAINSTABLE/FREETEXTTABLE) Fixes #11487~~ SQL Server: Support for Full-Text Search Table-Valued Functions (CONTAINSTABLE/FREETEXTTABLE) Jan 12, 2026

roji changed the title ~~SQL Server: Support for Full-Text Search Table-Valued Functions (CONTAINSTABLE/FREETEXTTABLE)~~ SQL Server: Support for full-text search TVFs (CONTAINSTABLE/FREETEXTTABLE) Jan 12, 2026

Abde1rahman1 and others added 4 commits January 13, 2026 00:33

Update test/EFCore.SqlServer.FunctionalTests/Query/SqlQuerySqlServerT…

8aeb974

…est.cs Co-authored-by: Shay Rojansky <roji@roji.org>

handle FullTextTableExpression class

5de1261

sqlserver: implement Full-Text Search table-valued functions as DbSet…

afb0bb4

… extensions

Merge branch 'feature-TVFs' of https://github.com/Abde1rahman1/efcore …

db1007f

…into feature-TVFs

roji requested changes Jan 13, 2026

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roji force-pushed the main branch 2 times, most recently from 249ae47 to 6b86657 Compare January 13, 2026 17:46

Abde1rahman1 added 2 commits January 17, 2026 12:01

handle All Comments

33510f6

return connectionString

622d95d

roji mentioned this pull request Jan 28, 2026

Implement SQL Server full-text search TVFs #37578

Merged

roji closed this Jan 28, 2026

	var alias = _queryCompilationContext.SqlAliasManager.GenerateTableAlias("ft");
	var alias = _queryCompilationContext.SqlAliasManager.GenerateTableAlias("fts");

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Abde1rahman1 commented Jan 12, 2026

Description

Key Architectural Changes

Example Usage

Related Issue

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