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fix: parquet negative DECIMAL loses sign (Issue #234) #243

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Merged
vmvarela merged 1 commit into from
Sep 12, 2026
Merged

fix: parquet negative DECIMAL loses sign (Issue #234) #243

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23 changes: 23 additions & 0 deletions build.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -2874,6 +2874,29 @@ pub fn build(b: *std.Build) void {
const run_loader_unit_tests = b.addRunArtifact(loader_unit_tests);
unit_test_step.dependOn(&run_loader_unit_tests.step);

// Unit tests for the Parquet loader (src/parquet.zig) — decimalToText sign handling
const parquet_unit_tests = b.addTest(.{
.root_module = b.createModule(.{
.root_source_file = b.path("src/parquet.zig"),
.target = target,
.optimize = optimize,
.link_libc = true,
}),
});
parquet_unit_tests.root_module.addImport("c", translate_c.createModule());
parquet_unit_tests.root_module.addImport("zig_parquet", zig_parquet.module("parquet"));
if (bundle_sqlite) {
parquet_unit_tests.root_module.addIncludePath(b.path("lib"));
parquet_unit_tests.root_module.addCSourceFile(.{
.file = b.path("lib/sqlite3.c"),
.flags = &.{ "-DSQLITE_OMIT_LOAD_EXTENSION=1", "-DSQLITE_ENABLE_MATH_FUNCTIONS=1" },
});
} else {
parquet_unit_tests.root_module.linkSystemLibrary("sqlite3", .{});
}
const run_parquet_unit_tests = b.addRunArtifact(parquet_unit_tests);
unit_test_step.dependOn(&run_parquet_unit_tests.step);

// ─── --stats / --profile integration tests ──────────────────────────

// Integration test: --stats on basic CSV with mixed types
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23 changes: 19 additions & 4 deletions src/parquet.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -91,13 +91,19 @@ fn decimalToText(value: i64, scale: i32, buf: *[64]u8) []const u8 {
// ponytail: manual int-to-text avoids bufPrint FixedWriter issues
return intToBuf(value, buf);
}
var pow10: i64 = 1;
var pow10: u64 = 1;
for (0..@as(usize, @intCast(scale))) |_| pow10 *= 10;
const int_part = @divTrunc(value, pow10);
const prefix = intToBuf(int_part, buf);
// ponytail: sign tracked independently (Issue #234) — @divTrunc(-1, 100)
// is 0, so intToBuf(int_part) alone drops the sign of |value| < pow10
const neg = value < 0;
const mag: u64 = @intCast(@abs(value));
if (neg) buf[0] = '-';
const off: usize = @intFromBool(neg);
const digits = intToBuf(@as(i64, @intCast(mag / pow10)), buf[off..]);
const prefix = buf[0 .. off + digits.len];
buf[prefix.len] = '.';
const dot_pos = prefix.len + 1;
var f = @as(u64, @intCast(@abs(@rem(value, pow10))));
var f = mag % pow10;
var pos: usize = @intCast(scale);
while (pos > 0) {
pos -= 1;
Expand Down Expand Up @@ -137,6 +143,15 @@ fn intToBuf(value: i64, buf: []u8) []const u8 {
return buf[0..end];
}

test "decimalToText: negative sub-unit value keeps its sign (Issue #234)" {
var buf: [64]u8 = undefined;
try std.testing.expectEqualStrings("-0.01", decimalToText(-1, 2, &buf));
try std.testing.expectEqualStrings("0.01", decimalToText(1, 2, &buf));
try std.testing.expectEqualStrings("-123.45", decimalToText(-12345, 2, &buf));
try std.testing.expectEqualStrings("-5", decimalToText(-5, 0, &buf));
try std.testing.expectEqualStrings("0.00", decimalToText(0, 2, &buf));
}

/// Map a Parquet physical type to a SQLite ColumnType (no logical type mapping).
fn physicalToAffinity(phys: parquet.format.PhysicalType) sqlite_mod.ColumnType {
return switch (phys) {
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