Giorgi / DuckDB.NET / 38554216686

93%

Build Type

push

github

Committed by Giorgi

Commit Message

Look at the target type of a list, struct or map read once per column

The list, struct and map readers worked out what to do with the target
type for every row: GetGenericArguments, which allocates, the test for
nullability, a type switch, and for a struct a lookup in the type cache
and a case-insensitive lookup of every property. The cache lambda of
the struct reader used a parameter of the method, so a closure was
allocated for every row, also on the path for Dictionary<string,
object>, and on .NET 8 a delegate as well.

Each reader now keeps what it worked out for the type it was asked for
last. A list of int, float, double or decimal, or of their nullable
forms, is created at its length and tests an item for NULL once. A
struct's properties are paired with the readers of their fields once.

200,000 rows, .NET 10: INTEGER[5] as List<int> 0.30 to 0.33 of the
time and 160 to 80 bytes per row, a list with NULLs as List<int?> 0.30,
List<long> 0.67, a STRUCT read into a class 0.63, a MAP 0.53 to 0.57.
.NET 8: 0.32 to 0.77. Nothing that is read changed; the new tests pass
on the build before and after.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TXdqHuNtM7YXS8B65qdfxX

Coverage Stats

2003 of 2213 branches covered (90.51%)

Branch coverage included in aggregate %.

83 of 90 new or added lines in 3 files covered. (92.22%)

4 existing lines in 3 files now uncovered.

3751 of 3978 relevant lines covered (94.29%)

1010877.1 hits per line