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feat(duckdb): Add transpilation support for nanoseconds used in date/time functions. #6617

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Merged
VaggelisD merged 4 commits into from
Dec 24, 2025
+132 −2
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feat(duckdb): Add transpilation support for nanoseconds used in date/time functions. #6617

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1fa600a
feat(duckdb): Add transpilation support for nanoseconds used in date/…
fivetran-amrutabhimsenayachit Dec 22, 2025
c8a9ce5
Address review comments: remove redundant casting and fix test cases
fivetran-amrutabhimsenayachit Dec 23, 2025
6555304
Address review comments: simplify code and improve clarity
fivetran-amrutabhimsenayachit Dec 23, 2025
5dc6181
feat(duckdb): Remove the unwrapping logic and remove the correspondin…
fivetran-amrutabhimsenayachit Dec 23, 2025
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71 changes: 69 additions & 2 deletions sqlglot/dialects/duckdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
from sqlglot import exp, generator, parser, tokens, transforms

from sqlglot.dialects.dialect import (
DATETIME_DELTA,
Dialect,
JSON_EXTRACT_TYPE,
NormalizationStrategy,
Expand All @@ -17,7 +18,7 @@
bool_xor_sql,
build_default_decimal_type,
count_if_to_sum,
date_delta_to_binary_interval_op,
date_delta_to_binary_interval_op as base_date_delta_to_binary_interval_op,
date_trunc_to_time,
datestrtodate_sql,
no_datetime_sql,
Expand Down Expand Up @@ -142,6 +143,42 @@ def _last_day_sql(self: DuckDB.Generator, expression: exp.LastDay) -> str:
return self.function_fallback_sql(expression)


def _is_nanosecond_unit(unit: t.Optional[exp.Expression]) -> bool:
return isinstance(unit, (exp.Var, exp.Literal)) and unit.name.upper() == "NANOSECOND"


def _handle_nanosecond_diff(
self: DuckDB.Generator,
end_time: exp.Expression,
start_time: exp.Expression,
) -> str:
"""Generate NANOSECOND diff using EPOCH_NS since DATE_DIFF doesn't support it."""
end_ns = exp.cast(end_time, exp.DataType.Type.TIMESTAMP_NS)
start_ns = exp.cast(start_time, exp.DataType.Type.TIMESTAMP_NS)

# Build expression tree: EPOCH_NS(end) - EPOCH_NS(start)
return self.sql(
exp.Sub(this=exp.func("EPOCH_NS", end_ns), expression=exp.func("EPOCH_NS", start_ns))
)


def _handle_nanosecond_add(
self: DuckDB.Generator,
timestamp: exp.Expression,
nanoseconds: exp.Expression,
) -> str:
"""Generate NANOSECOND add using EPOCH_NS and make_timestamp_ns since INTERVAL doesn't support it."""
timestamp_ns = exp.cast(timestamp, exp.DataType.Type.TIMESTAMP_NS)

# Build expression tree: make_timestamp_ns(EPOCH_NS(timestamp) + nanoseconds)
return self.sql(
exp.func(
"make_timestamp_ns",
exp.Add(this=exp.func("EPOCH_NS", timestamp_ns), expression=nanoseconds),
)
)


def _to_boolean_sql(self: DuckDB.Generator, expression: exp.ToBoolean) -> str:
"""
Transpile TO_BOOLEAN and TRY_TO_BOOLEAN functions from Snowflake to DuckDB equivalent.
Expand Down Expand Up @@ -215,6 +252,11 @@ def _date_sql(self: DuckDB.Generator, expression: exp.Date) -> str:

# BigQuery -> DuckDB conversion for the TIME_DIFF function
def _timediff_sql(self: DuckDB.Generator, expression: exp.TimeDiff) -> str:
unit = expression.unit

if _is_nanosecond_unit(unit):
return _handle_nanosecond_diff(self, expression.expression, expression.this)

this = exp.cast(expression.this, exp.DataType.Type.TIME)
expr = exp.cast(expression.expression, exp.DataType.Type.TIME)

Expand All @@ -223,6 +265,27 @@ def _timediff_sql(self: DuckDB.Generator, expression: exp.TimeDiff) -> str:
return self.func("DATE_DIFF", unit_to_str(expression), expr, this)


def date_delta_to_binary_interval_op(
cast: bool = True,
) -> t.Callable[[DuckDB.Generator, DATETIME_DELTA], str]:
"""DuckDB override to handle NANOSECOND operations; delegates other units to base."""
base_impl = base_date_delta_to_binary_interval_op(cast=cast)
Comment on lines +268 to +272
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@VaggelisD VaggelisD Dec 24, 2025

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Lets prefix the function with _ since its local to DuckDB, by doing so we can also leave the import name as is e.g:

```suggestion
def _date_delta_to_binary_interval_op(
    cast: bool = True,
) -> t.Callable[[DuckDB.Generator, DATETIME_DELTA], str]:
    """DuckDB override to handle NANOSECOND operations; delegates other units to base."""
    base_impl = date_delta_to_binary_interval_op(cast=cast)


def duckdb_date_delta_sql(self: DuckDB.Generator, expression: DATETIME_DELTA) -> str:
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@VaggelisD VaggelisD Dec 24, 2025

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[Nit] Lets also prefix this with _

unit = expression.unit

# Handle NANOSECOND unit (DuckDB doesn't support INTERVAL ... NANOSECOND)
if _is_nanosecond_unit(unit):
interval_value = expression.expression
if isinstance(interval_value, exp.Interval):
interval_value = interval_value.this
return _handle_nanosecond_add(self, expression.this, interval_value)

return base_impl(self, expression)

return duckdb_date_delta_sql


@unsupported_args(("expression", "DuckDB's ARRAY_SORT does not support a comparator."))
def _array_sort_sql(self: DuckDB.Generator, expression: exp.ArraySort) -> str:
return self.func("ARRAY_SORT", expression.this)
Expand Down Expand Up @@ -439,9 +502,13 @@ def _build_week_trunc_expression(date_expr: exp.Expression, start_dow: int) -> e


def _date_diff_sql(self: DuckDB.Generator, expression: exp.DateDiff) -> str:
unit = expression.unit

if _is_nanosecond_unit(unit):
return _handle_nanosecond_diff(self, expression.this, expression.expression)
Comment on lines +507 to +508
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@VaggelisD VaggelisD Dec 24, 2025

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[Nit] We can inline the implementations of both _handle_nanosecond_diff and _handle_nanosecond_add directly under their branches now that they're both small enough after the recent changes, leaving it up to you


this = _implicit_datetime_cast(expression.this)
expr = _implicit_datetime_cast(expression.expression)
unit = expression.args.get("unit")

# DuckDB's WEEK diff does not respect Monday crossing (week boundaries), it checks (end_day - start_day) / 7:
# SELECT DATE_DIFF('WEEK', CAST('2024-12-13' AS DATE), CAST('2024-12-17' AS DATE)) --> 0 (Monday crossed)
Expand Down
63 changes: 63 additions & 0 deletions tests/dialects/test_snowflake.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2475,6 +2475,69 @@ def test_timestamps(self):
},
)

# Test DATEDIFF with NANOSECOND - DuckDB uses EPOCH_NS since DATE_DIFF doesn't support NANOSECOND
self.validate_all(
"DATEDIFF(NANOSECOND, '2023-01-01 10:00:00.000000000', '2023-01-01 10:00:00.123456789')",
write={
"duckdb": "EPOCH_NS(CAST('2023-01-01 10:00:00.123456789' AS TIMESTAMP_NS)) - EPOCH_NS(CAST('2023-01-01 10:00:00.000000000' AS TIMESTAMP_NS))",
"snowflake": "DATEDIFF(NANOSECOND, '2023-01-01 10:00:00.000000000', '2023-01-01 10:00:00.123456789')",
},
)

# Test DATEDIFF with NANOSECOND on columns
self.validate_all(
"DATEDIFF(NANOSECOND, start_time, end_time)",
write={
"duckdb": "EPOCH_NS(CAST(end_time AS TIMESTAMP_NS)) - EPOCH_NS(CAST(start_time AS TIMESTAMP_NS))",
"snowflake": "DATEDIFF(NANOSECOND, start_time, end_time)",
},
)

# Test DATEADD with NANOSECOND - DuckDB uses MAKE_TIMESTAMP_NS since INTERVAL doesn't support NANOSECOND
self.validate_all(
"DATEADD(NANOSECOND, 123456789, '2023-01-01 10:00:00.000000000')",
write={
"duckdb": "MAKE_TIMESTAMP_NS(EPOCH_NS(CAST('2023-01-01 10:00:00.000000000' AS TIMESTAMP_NS)) + 123456789)",
"snowflake": "DATEADD(NANOSECOND, 123456789, '2023-01-01 10:00:00.000000000')",
},
)

# Test DATEADD with NANOSECOND on columns
self.validate_all(
"DATEADD(NANOSECOND, nano_offset, timestamp_col)",
write={
"duckdb": "MAKE_TIMESTAMP_NS(EPOCH_NS(CAST(timestamp_col AS TIMESTAMP_NS)) + nano_offset)",
"snowflake": "DATEADD(NANOSECOND, nano_offset, timestamp_col)",
},
)

# Test negative NANOSECOND values (subtraction)
self.validate_all(
"DATEADD(NANOSECOND, -123456789, '2023-01-01 10:00:00.500000000')",
write={
"duckdb": "MAKE_TIMESTAMP_NS(EPOCH_NS(CAST('2023-01-01 10:00:00.500000000' AS TIMESTAMP_NS)) + -123456789)",
"snowflake": "DATEADD(NANOSECOND, -123456789, '2023-01-01 10:00:00.500000000')",
},
)

# Test TIMESTAMPDIFF with NANOSECOND - Snowflake parser converts to DATEDIFF
self.validate_all(
"TIMESTAMPDIFF(NANOSECOND, '2023-01-01 10:00:00.000000000', '2023-01-01 10:00:00.123456789')",
write={
"duckdb": "EPOCH_NS(CAST('2023-01-01 10:00:00.123456789' AS TIMESTAMP_NS)) - EPOCH_NS(CAST('2023-01-01 10:00:00.000000000' AS TIMESTAMP_NS))",
"snowflake": "DATEDIFF(NANOSECOND, '2023-01-01 10:00:00.000000000', '2023-01-01 10:00:00.123456789')",
},
)

# Test TIMESTAMPADD with NANOSECOND - Snowflake parser converts to DATEADD
self.validate_all(
"TIMESTAMPADD(NANOSECOND, 123456789, '2023-01-01 10:00:00.000000000')",
write={
"duckdb": "MAKE_TIMESTAMP_NS(EPOCH_NS(CAST('2023-01-01 10:00:00.000000000' AS TIMESTAMP_NS)) + 123456789)",
"snowflake": "DATEADD(NANOSECOND, 123456789, '2023-01-01 10:00:00.000000000')",
},
)

self.validate_identity("DATEADD(y, 5, x)", "DATEADD(YEAR, 5, x)")
self.validate_identity("DATEADD(y, 5, x)", "DATEADD(YEAR, 5, x)")
self.validate_identity("DATE_PART(yyy, x)", "DATE_PART(YEAR, x)")
Expand Down