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Add Half type support for SQLite (#30931) #37481

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@kimjaejung96 kimjaejung96 commented Jan 11, 2026

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Summary

Add Half (16-bit floating point) type support for Microsoft.Data.Sqlite and EF Core SQLite provider.

Fixes #30931

Changes

Microsoft.Data.Sqlite (ADO.NET layer)

File Change
SqliteValueReader.cs Add GetFieldValue<Half> support
SqliteValueBinder.cs Add Half binding + type mapping

EF Core SQLite Provider

File Change
SqliteHalfTypeMapping.cs New - SQLite-specific type mapping
SqliteTypeMappingSource.cs Register Half mapping

Tests

File Change
SqliteDataReaderTest.cs Half read/write tests
SqliteTypeMappingSourceTest.cs CLR/Store type mapping tests (including UNREALISTIC)
SqliteTypeMappingTest.cs SQL literal generation + clone test

Design Notes

Based on #35328 feedback:

  1. SQLite-specific only - No changes to EFCore.Relational (no HalfTypeMapping in common layer)
  2. No DbType - System.Data.DbType has no Half value, so DbType is null
  3. Float pattern - Follows existing float implementation (read via GetFloat(), bind via BindDouble())
  4. Conditional compilation - Uses #if NET6_0_OR_GREATER for netstandard2.0 compatibility

@kimjaejung96
Add Half type support for SQLite
37c25c6 
- Add Half support in SqliteValueReader.GetFieldValue<T>
- Add Half binding in SqliteValueBinder
- Add SqliteHalfTypeMapping for EF Core SQLite provider
- SQLite-specific implementation only (per maintainer feedback)
- Use REAL store type, DbType is null (no DbType.Half exists)

Fixes dotnet#30931
@kimjaejung96 kimjaejung96 requested a review from a team as a code owner January 11, 2026 06:04
bricelam
bricelam reviewed Jan 12, 2026
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Looking good to me.

You should also add logic for Half to SqliteDatabaseModelFactory.

src/Microsoft.Data.Sqlite.Core/SqliteValueReader.cs Outdated
#if NET6_0_OR_GREATER
if (typeof(T) == typeof(Half))
{
return (T)(object)(Half)GetFloat(ordinal);
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Either add GetHalf, or use GetDouble here to avoid extra conversions.

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(below too)

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AndriySvyryd commented Jan 12, 2026

For reference, the previous attempt was #35328

@kimjaejung96
Address PR review feedback
10d5a20 
- Use GetDouble instead of GetFloat for Half reading (avoids extra conversion)
- Add Half scaffolding support to SqliteDatabaseModelFactory
  - Add HALF, FLOAT16 type hints for Half CLR type mapping
  - Add Half range validation in REAL value type handling
  - Add Half default value parsing
@kimjaejung96
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kimjaejung96 commented Jan 12, 2026

Thanks again @bricelam — I pushed updates addressing the feedback:

  • SqliteValueReader: Half now uses GetDouble
  • Added Half handling to SqliteDatabaseModelFactory for scaffolding

(Also, thanks to AndriySvyryd for pointing me to the previous attempt.)

bricelam
bricelam approved these changes Jan 13, 2026
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LGTM

src/EFCore.Sqlite.Core/Scaffolding/Internal/SqliteDatabaseModelFactory.cs Outdated

private static readonly HashSet<string> _floatTypes = new(StringComparer.OrdinalIgnoreCase) { "SINGLE" };

private static readonly HashSet<string> _halfTypes = new(StringComparer.OrdinalIgnoreCase) { "HALF", "FLOAT16" };
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FLOAT16 seems inconsistent with the other floating-point types. I'd go with just HALF.

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@bricelam bricelam Jan 13, 2026 •
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BTW, the philosophy behind these names was to use names specified in the SQL standard, if available, or at least one generic/.NET name to allow some way of preserving the .NET type in the schema. But, the default EF Core mapping will always adhere to the STRICT rules.

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Thx !
Updated SqliteDatabaseModelFactory to drop FLOAT16 and keep only HALF as the explicit type hint (per your suggestion).

@roji roji force-pushed the main branch 2 times, most recently from 249ae47 to 6b86657 Compare January 13, 2026 17:46
@kimjaejung96
Remove FLOAT16 from Half type hints
f6d7298 
Per reviewer feedback, keep only HALF for consistency with other
floating-point type hints (SINGLE for float).
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Microsoft.Data.Sqlite: Support Half

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@kimjaejung96 @AndriySvyryd @bricelam @roji