All integers, decimal & guid

[unconverged]

This pull request brings support for all of integral types, decimal (through string) and GUID (through string).

Fix #55 Fix #56

[coveralls]

Pull Request Test Coverage Report for Build 2885165571

• -22 of 55 (60.0%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+2.0%) to 75.697%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
DuckDB.NET.Data/DuckDBDataReader.cs	10	20	50.0%
DuckDB.NET.Data/DuckDBParameter.cs	12	24	50.0%
<!--	Total:	33	55	60.0%	-->

Files with Coverage Reduction	New Missed Lines	%
DuckDB.NET.Data/DuckDBDataReader.cs	1	57.41%
<!--	Total:	1		-->

Totals
Change from base Build 2728373780:	2.0%
Covered Lines:	463
Relevant Lines:	597

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 2885165571

• 33 of 55 (60.0%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+2.0%) to 75.697%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
DuckDB.NET.Data/DuckDBDataReader.cs	10	20	50.0%
DuckDB.NET.Data/DuckDBParameter.cs	12	24	50.0%
<!--	Total:	33	55	60.0%	-->

Files with Coverage Reduction	New Missed Lines	%
DuckDB.NET.Data/DuckDBDataReader.cs	1	57.41%
<!--	Total:	1		-->

Totals
Change from base Build 2728373780:	2.0%
Covered Lines:	463
Relevant Lines:	597

---

💛 - Coveralls

[Giorgi]

@IvaYan Thanks for the PR. We should probably treat DUCKDB_TYPE_UUID as Guid too.

[Giorgi]

Also, decimal should use duckdb_value_decimal to get value instead of parsing from string.

[unconverged]

Also, decimal should use duckdb_value_decimal to get value instead of parsing from string.

This does not seem possible. DuckDB uses the following structure to represent a decimal value:

typedef struct {
    uint8_t width;
    uint8_t scale;

    duckdb_hugeint value;
} duckdb_decimal;

and duckdb_hugeint is defined as follows:

typedef struct {
    uint64_t lower;
    int64_t upper;
} duckdb_hugeint;

It does not seem possible to reconstruct C#'s decimal given this data. Although we can do something like this:

var d = (duckdb_decimal.value.upper * 2m ^ 64 + duckdb_decimal.value.lower) / 10m ^ duckdb_decimal.scale;

this approach would not work. First of all, we could not apply the operator ^ to decimals (C# does not support this). Secondly, I'm not sure division can safely preserve the position of the float point. And thirdly, I'm not sure that this approach is going to be faster than to simply parse.

[Giorgi]

Ok, let's keep decimal as is.

[unconverged]

Thanks for the PR. We should probably treat DUCKDB_TYPE_UUID as Guid too.

Good idea, working on it. However, there are some strange things. I have a value of UUID type. DuckDB identifies the value as UUID. The docs indicate that UUID is actually a duckdb_hudeint (128 bit integer), but when I try getting this value as a HugeInt, I get 0. When I try getting the same value as a string, I get an empty string. Huh, something wrong, apparently.

[Giorgi]

Try asking at Discord or GitHub discussions.