Why both "real" and "float" get mapped to "Single" instead of "Double"?

Question

I am using System.Data.SQLite 1.0.90 with VS2013 and EntityFramework 5 in Model-First mode (=EDMX).

I created a new SQLite database containing a table:

CREATE TABLE [..]
  [Test1integer] integer,
  [Test2int] int,
  [Test3smallint] smallint,
  [Test4tinyint] tinyint,
  [Test5bigint] bigint,
  [Test6money] money,
  [Test7float] float,
  [Test8real] real,
  [Test9decimal] decimal,
  [Test10numeric18_5] numeric(18,5), [..]

The relevant parts are Test7float and Test8real.

After having executed Update Model from Database... the EDMX now contains this:

SSDL:

      <Property Name="Test1integer" Type="integer" />
      <Property Name="Test2int" Type="int" />
      <Property Name="Test3smallint" Type="smallint" />
      <Property Name="Test4tinyint" Type="tinyint" />
      <Property Name="Test5bigint" Type="integer" />
      <Property Name="Test6money" Type="decimal" Precision="53" Scale="0" />
      <Property Name="Test7float" Type="real" />
      <Property Name="Test8real" Type="real" />
      <Property Name="Test9decimal" Type="decimal" Precision="53" Scale="0" />
      <Property Name="Test10numeric18_5" Type="decimal" Precision="18" Scale="5" />

The relevant parts are Test7float and Test8real.

CSDL:

      <Property Name="Test1integer" Type="Int64" />
      <Property Name="Test2int" Type="Int32" />
      <Property Name="Test3smallint" Type="Int16" />
      <Property Name="Test4tinyint" Type="Byte" />
      <Property Name="Test5bigint" Type="Int64" />
      <Property Name="Test6money" Type="Decimal" Precision="53" Scale="0" />
      <Property Name="Test7float" Type="Single" />
      <Property Name="Test8real" Type="Single" />
      <Property Name="Test9decimal" Type="Decimal" Precision="53" Scale="0" />
      <Property Name="Test10numeric18_5" Type="Decimal" Precision="18" Scale="5" />

The relevant parts are Test7float and Test8real.

Problem

Test7float wrongly became "real" + "Single" -- and the designer also does not allow "Double" here.

The SQLite3 docs ( http://www.sqlite.org/datatype3.html ) clearly state that "real" is a 8-byte IEEE floating point number and "float" is only a synonym for "real" -- so in every case "Double" (8 byte) should be preferred over "Single" (4 byte).

Am I doing something wrong or did I misunderstand something? If not: Where are things going wrong and how can I fix them?

Should I create a bug report for this?

Answer 1

Looks like a bug in the mapping driver.

The type used to declare a column is only used for affinity (you can declare a column as float and store blobs in it if you want).

When reporting a table structure, SQLite merely returns the SQL definition that was used to create its fields (and alter them, if applicable).

Thus your driver only has access to "float" for the field type, and likely maps it to "single" through some generic code, that may not have been written with SQLite in mind (or overridden for SQLite anyway).