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fix: cast numeric FORMAT arguments for DuckDB #479

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fix: cast numeric FORMAT arguments for DuckDB #479

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32 changes: 32 additions & 0 deletions format_precision_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
package main

import (
"testing"

"github.com/dolthub/go-mysql-server/enginetest"
"github.com/dolthub/go-mysql-server/enginetest/queries"
"github.com/dolthub/go-mysql-server/enginetest/scriptgen/setup"
"github.com/dolthub/go-mysql-server/sql"
"github.com/stretchr/testify/require"
)

func TestFormatPreservesNumericPrecision(t *testing.T) {
h := NewDefaultDuckHarness()
h.Setup(setup.MydbData, setup.MytableData)
e, err := h.NewEngine(t)
require.NoError(t, err)
defer e.Close()

for _, test := range []queries.QueryTest{
{
Query: "SELECT FORMAT(9007199254740993, 0) FROM mytable LIMIT 1",
Expected: []sql.Row{{"9,007,199,254,740,993"}},
},
{
Query: "SELECT FORMAT(CAST('1234567890123456789012345678.12' AS DECIMAL(30, 2)), 2) FROM mytable LIMIT 1",
Expected: []sql.Row{{"1,234,567,890,123,456,789,012,345,678.12"}},
},
} {
enginetest.TestQueryWithEngine(t, h, e, test)
}
}
142 changes: 129 additions & 13 deletions transpiler/translate.go
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Original file line number Diff line number Diff line change
Expand Up @@ -630,30 +630,146 @@ def rewrite_mysql_for_duckdb(node):
# MySQL FORMAT(x, d[, locale]) is number-to-string with grouping.
# DuckDB FORMAT is {fmt}; map the scale and swap separators for common EU locales.
if isinstance(node, exp.NumberToStr):
# DuckDB rejects precision specifiers for integer values. Keep the format
# string dynamic so DuckDB can select its integer form at execution time;
# casting every value to DOUBLE would silently lose large-number precision.
value = node.this
integer_types = [
exp.Literal.string(t)
for t in (
"TINYINT", "SMALLINT", "INTEGER", "BIGINT", "HUGEINT",
"UTINYINT", "USMALLINT", "UINTEGER", "UBIGINT",
)
]
string_types = [
exp.Literal.string(t)
for t in ("VARCHAR", "CHAR", "BPCHAR", "TEXT", "STRING")
]
value_type = exp.Anonymous(this="typeof", expressions=[value.copy()])
is_integer = exp.In(this=value_type.copy(), expressions=integer_types)
is_decimal = exp.Like(this=value_type.copy(), expression=exp.Literal.string("DECIMAL%%"))
is_string = exp.In(this=value_type, expressions=string_types)
digits = node.args.get("format")
culture = node.args.get("culture")
if isinstance(digits, exp.Literal) and digits.is_int:
fmt = "{:,." + str(int(digits.this)) + "f}"
formatted = exp.Anonymous(
this="format",
expressions=[exp.Literal.string(fmt), value],
)
format_expr = exp.Literal.string(fmt)
integer_suffix = None
if int(digits.this) > 0:
integer_suffix = exp.Anonymous(
this="concat",
expressions=[
exp.Literal.string("."),
exp.Anonymous(
this="repeat",
expressions=[exp.Literal.string("0"), digits.copy()],
),
],
)
else:
formatted = exp.Anonymous(
this="format",
format_expr = exp.Anonymous(
this="concat",
expressions=[
exp.Literal.string("{:,."),
exp.Cast(this=digits, to=exp.DataType.build("TEXT")),
exp.Literal.string("f}"),
],
)
integer_suffix = exp.Case(
ifs=[
exp.If(
this=exp.And(
this=is_integer.copy(),
expression=exp.GT(this=digits.copy(), expression=exp.Literal.number(0)),
),
true=exp.Anonymous(
this="concat",
expressions=[
exp.Literal.string("."),
exp.Anonymous(
this="repeat",
expressions=[exp.Literal.string("0"), digits.copy()],
),
],
),
)
],
default=exp.Literal.string(""),
)
numeric_format_expr = exp.Case(
ifs=[exp.If(this=is_integer.copy(), true=exp.Literal.string("{:,}"))],
default=format_expr,
)
numeric_formatted = exp.Anonymous(
this="format",
expressions=[numeric_format_expr, value.copy()],
)
string_formatted = exp.Anonymous(
this="format",
expressions=[
format_expr.copy(),
exp.TryCast(this=value.copy(), to=exp.DataType.build("DOUBLE")),
],
)
rounded_decimal = exp.Cast(
this=exp.Anonymous(
this="round",
expressions=[value.copy(), digits.copy()],
),
to=exp.DataType.build("TEXT"),
)
decimal_integer = exp.Anonymous(
this="split_part",
expressions=[rounded_decimal.copy(), exp.Literal.string("."), exp.Literal.number(1)],
)
if isinstance(digits, exp.Literal) and digits.is_int and int(digits.this) > 0:
decimal_fraction = exp.Anonymous(
this="rpad",
expressions=[
exp.Anonymous(
this="concat",
expressions=[
exp.Literal.string("{:,."),
exp.Cast(this=digits, to=exp.DataType.build("TEXT")),
exp.Literal.string("f}"),
],
this="split_part",
expressions=[rounded_decimal.copy(), exp.Literal.string("."), exp.Literal.number(2)],
),
value,
digits.copy(),
exp.Literal.string("0"),
],
)
decimal_text = exp.Anonymous(
this="concat",
expressions=[decimal_integer, exp.Literal.string("."), decimal_fraction],
)
else:
decimal_text = decimal_integer
# DuckDB FORMAT currently routes DECIMAL through a floating formatter.
# Group the rounded TEXT representation instead, which keeps up to the
# full DECIMAL precision supported by DuckDB.
decimal_formatted = decimal_text
for grouping_pass in range(12):
pattern = r"(\d+)(\d{3})([.]|$)" if grouping_pass == 0 else r"(\d+)(\d{3})([,.]|$)"
decimal_formatted = exp.Anonymous(
this="regexp_replace",
expressions=[
decimal_formatted,
exp.Literal.string(pattern),
exp.Literal.string(r"\1,\2\3"),
exp.Literal.string("g"),
],
)
formatted = exp.Case(
ifs=[
exp.If(this=is_string, true=string_formatted),
exp.If(this=is_decimal, true=decimal_formatted),
],
default=numeric_formatted,
)
if integer_suffix is not None:
formatted = exp.Anonymous(
this="concat",
expressions=[formatted, exp.Case(
ifs=[exp.If(this=is_integer, true=integer_suffix)],
default=exp.Literal.string(""),
)],
)
if isinstance(culture, exp.Literal) and culture.is_string:
loc = str(culture.this).lower().replace("-", "_")
prefix = loc.split("_", 1)[0]
Expand Down
28 changes: 21 additions & 7 deletions transpiler/translate_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ func TestTranslate(t *testing.T) {
name string
input string
expected string
validate func(*testing.T, string)
}{

{
Expand Down Expand Up @@ -82,14 +83,25 @@ func TestTranslate(t *testing.T) {
expected: "SELECT FLOOR(i), AVG(LENGTH(s)) FROM mytable AS mt GROUP BY 1 ORDER BY FLOOR(i) DESC",
},
{
name: "FORMAT two-arg uses DuckDB fmt grouping",
input: "SELECT FORMAT(i, 3) FROM mytable",
expected: "SELECT FORMAT('{:,.3f}', i) FROM mytable",
name: "FORMAT two-arg uses DuckDB fmt grouping",
input: "SELECT FORMAT(i, 3) FROM mytable",
validate: func(t *testing.T, result string) {
if !strings.Contains(result, "TYPEOF(i)") || !strings.Contains(result, "THEN '{:,}'") {
t.Errorf("FORMAT translation must select an integer-safe format dynamically: %s", result)
}
if strings.Contains(result, "FORMAT('{:,.3f}', CAST(i AS DOUBLE))") {
t.Errorf("FORMAT translation must not coerce the value to DOUBLE: %s", result)
}
},
},
{
name: "FORMAT with da_DK swaps grouping separators",
input: "SELECT FORMAT(i, 3, 'da_DK') FROM mytable",
expected: "SELECT REPLACE(REPLACE(REPLACE(FORMAT('{:,.3f}', i), ',', '\x01'), '.', ','), '\x01', '.') FROM mytable",
name: "FORMAT with da_DK swaps grouping separators",
input: "SELECT FORMAT(i, 3, 'da_DK') FROM mytable",
validate: func(t *testing.T, result string) {
if !strings.Contains(result, "REPLACE(REPLACE(REPLACE(") || !strings.Contains(result, "TYPEOF(i)") {
t.Errorf("FORMAT locale translation lost the precision-safe formatter: %s", result)
}
},
},
{
name: "aggregate without GROUP BY wraps non-agg columns",
Expand Down Expand Up @@ -618,7 +630,9 @@ func TestTranslate(t *testing.T) {

trimmedResult := strings.TrimSpace(result)
fmt.Println("trimmedResult:", trimmedResult)
if trimmedResult != tc.expected {
if tc.validate != nil {
tc.validate(t, trimmedResult)
} else if trimmedResult != tc.expected {
t.Errorf("translate(%q) = %v; want %v", tc.input, trimmedResult, tc.expected)
}
})
Expand Down
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