sqlglot.dialects.duckdb

   1from __future__ import annotations
   2
   3import typing as t
   4
   5from sqlglot import exp, generator, parser, tokens, transforms
   6from sqlglot.expressions import DATA_TYPE
   7from sqlglot.dialects.dialect import (
   8    Dialect,
   9    JSON_EXTRACT_TYPE,
  10    NormalizationStrategy,
  11    Version,
  12    approx_count_distinct_sql,
  13    arrow_json_extract_sql,
  14    binary_from_function,
  15    bool_xor_sql,
  16    build_default_decimal_type,
  17    count_if_to_sum,
  18    date_trunc_to_time,
  19    datestrtodate_sql,
  20    no_datetime_sql,
  21    encode_decode_sql,
  22    build_formatted_time,
  23    inline_array_unless_query,
  24    no_comment_column_constraint_sql,
  25    no_time_sql,
  26    no_timestamp_sql,
  27    pivot_column_names,
  28    rename_func,
  29    strposition_sql,
  30    str_to_time_sql,
  31    timestamptrunc_sql,
  32    timestrtotime_sql,
  33    unit_to_var,
  34    unit_to_str,
  35    sha256_sql,
  36    build_regexp_extract,
  37    explode_to_unnest_sql,
  38    no_make_interval_sql,
  39    groupconcat_sql,
  40)
  41from sqlglot.generator import unsupported_args
  42from sqlglot.helper import seq_get
  43from sqlglot.tokens import TokenType
  44from sqlglot.parser import binary_range_parser
  45
  46DATETIME_DELTA = t.Union[
  47    exp.DateAdd, exp.TimeAdd, exp.DatetimeAdd, exp.TsOrDsAdd, exp.DateSub, exp.DatetimeSub
  48]
  49
  50
  51def _date_delta_sql(self: DuckDB.Generator, expression: DATETIME_DELTA) -> str:
  52    this = expression.this
  53    unit = unit_to_var(expression)
  54    op = (
  55        "+"
  56        if isinstance(expression, (exp.DateAdd, exp.TimeAdd, exp.DatetimeAdd, exp.TsOrDsAdd))
  57        else "-"
  58    )
  59
  60    to_type: t.Optional[DATA_TYPE] = None
  61    if isinstance(expression, exp.TsOrDsAdd):
  62        to_type = expression.return_type
  63    elif this.is_string:
  64        # Cast string literals (i.e function parameters) to the appropriate type for +/- interval to work
  65        to_type = (
  66            exp.DataType.Type.DATETIME
  67            if isinstance(expression, (exp.DatetimeAdd, exp.DatetimeSub))
  68            else exp.DataType.Type.DATE
  69        )
  70
  71    this = exp.cast(this, to_type) if to_type else this
  72
  73    expr = expression.expression
  74    interval = expr if isinstance(expr, exp.Interval) else exp.Interval(this=expr, unit=unit)
  75
  76    return f"{self.sql(this)} {op} {self.sql(interval)}"
  77
  78
  79# BigQuery -> DuckDB conversion for the DATE function
  80def _date_sql(self: DuckDB.Generator, expression: exp.Date) -> str:
  81    result = f"CAST({self.sql(expression, 'this')} AS DATE)"
  82    zone = self.sql(expression, "zone")
  83
  84    if zone:
  85        date_str = self.func("STRFTIME", result, "'%d/%m/%Y'")
  86        date_str = f"{date_str} || ' ' || {zone}"
  87
  88        # This will create a TIMESTAMP with time zone information
  89        result = self.func("STRPTIME", date_str, "'%d/%m/%Y %Z'")
  90
  91    return result
  92
  93
  94# BigQuery -> DuckDB conversion for the TIME_DIFF function
  95def _timediff_sql(self: DuckDB.Generator, expression: exp.TimeDiff) -> str:
  96    this = exp.cast(expression.this, exp.DataType.Type.TIME)
  97    expr = exp.cast(expression.expression, exp.DataType.Type.TIME)
  98
  99    # Although the 2 dialects share similar signatures, BQ seems to inverse
 100    # the sign of the result so the start/end time operands are flipped
 101    return self.func("DATE_DIFF", unit_to_str(expression), expr, this)
 102
 103
 104@unsupported_args(("expression", "DuckDB's ARRAY_SORT does not support a comparator."))
 105def _array_sort_sql(self: DuckDB.Generator, expression: exp.ArraySort) -> str:
 106    return self.func("ARRAY_SORT", expression.this)
 107
 108
 109def _sort_array_sql(self: DuckDB.Generator, expression: exp.SortArray) -> str:
 110    name = "ARRAY_REVERSE_SORT" if expression.args.get("asc") == exp.false() else "ARRAY_SORT"
 111    return self.func(name, expression.this)
 112
 113
 114def _build_sort_array_desc(args: t.List) -> exp.Expression:
 115    return exp.SortArray(this=seq_get(args, 0), asc=exp.false())
 116
 117
 118def _build_date_diff(args: t.List) -> exp.Expression:
 119    return exp.DateDiff(this=seq_get(args, 2), expression=seq_get(args, 1), unit=seq_get(args, 0))
 120
 121
 122def _build_generate_series(end_exclusive: bool = False) -> t.Callable[[t.List], exp.GenerateSeries]:
 123    def _builder(args: t.List) -> exp.GenerateSeries:
 124        # Check https://duckdb.org/docs/sql/functions/nested.html#range-functions
 125        if len(args) == 1:
 126            # DuckDB uses 0 as a default for the series' start when it's omitted
 127            args.insert(0, exp.Literal.number("0"))
 128
 129        gen_series = exp.GenerateSeries.from_arg_list(args)
 130        gen_series.set("is_end_exclusive", end_exclusive)
 131
 132        return gen_series
 133
 134    return _builder
 135
 136
 137def _build_make_timestamp(args: t.List) -> exp.Expression:
 138    if len(args) == 1:
 139        return exp.UnixToTime(this=seq_get(args, 0), scale=exp.UnixToTime.MICROS)
 140
 141    return exp.TimestampFromParts(
 142        year=seq_get(args, 0),
 143        month=seq_get(args, 1),
 144        day=seq_get(args, 2),
 145        hour=seq_get(args, 3),
 146        min=seq_get(args, 4),
 147        sec=seq_get(args, 5),
 148    )
 149
 150
 151def _show_parser(*args: t.Any, **kwargs: t.Any) -> t.Callable[[DuckDB.Parser], exp.Show]:
 152    def _parse(self: DuckDB.Parser) -> exp.Show:
 153        return self._parse_show_duckdb(*args, **kwargs)
 154
 155    return _parse
 156
 157
 158def _struct_sql(self: DuckDB.Generator, expression: exp.Struct) -> str:
 159    args: t.List[str] = []
 160
 161    # BigQuery allows inline construction such as "STRUCT<a STRING, b INTEGER>('str', 1)" which is
 162    # canonicalized to "ROW('str', 1) AS STRUCT(a TEXT, b INT)" in DuckDB
 163    # The transformation to ROW will take place if:
 164    #  1. The STRUCT itself does not have proper fields (key := value) as a "proper" STRUCT would
 165    #  2. A cast to STRUCT / ARRAY of STRUCTs is found
 166    ancestor_cast = expression.find_ancestor(exp.Cast)
 167    is_bq_inline_struct = (
 168        (expression.find(exp.PropertyEQ) is None)
 169        and ancestor_cast
 170        and any(
 171            casted_type.is_type(exp.DataType.Type.STRUCT)
 172            for casted_type in ancestor_cast.find_all(exp.DataType)
 173        )
 174    )
 175
 176    for i, expr in enumerate(expression.expressions):
 177        is_property_eq = isinstance(expr, exp.PropertyEQ)
 178        value = expr.expression if is_property_eq else expr
 179
 180        if is_bq_inline_struct:
 181            args.append(self.sql(value))
 182        else:
 183            key = expr.name if is_property_eq else f"_{i}"
 184            args.append(f"{self.sql(exp.Literal.string(key))}: {self.sql(value)}")
 185
 186    csv_args = ", ".join(args)
 187
 188    return f"ROW({csv_args})" if is_bq_inline_struct else f"{{{csv_args}}}"
 189
 190
 191def _datatype_sql(self: DuckDB.Generator, expression: exp.DataType) -> str:
 192    if expression.is_type("array"):
 193        return f"{self.expressions(expression, flat=True)}[{self.expressions(expression, key='values', flat=True)}]"
 194
 195    # Modifiers are not supported for TIME, [TIME | TIMESTAMP] WITH TIME ZONE
 196    if expression.is_type(
 197        exp.DataType.Type.TIME, exp.DataType.Type.TIMETZ, exp.DataType.Type.TIMESTAMPTZ
 198    ):
 199        return expression.this.value
 200
 201    return self.datatype_sql(expression)
 202
 203
 204def _json_format_sql(self: DuckDB.Generator, expression: exp.JSONFormat) -> str:
 205    sql = self.func("TO_JSON", expression.this, expression.args.get("options"))
 206    return f"CAST({sql} AS TEXT)"
 207
 208
 209def _unix_to_time_sql(self: DuckDB.Generator, expression: exp.UnixToTime) -> str:
 210    scale = expression.args.get("scale")
 211    timestamp = expression.this
 212
 213    if scale in (None, exp.UnixToTime.SECONDS):
 214        return self.func("TO_TIMESTAMP", timestamp)
 215    if scale == exp.UnixToTime.MILLIS:
 216        return self.func("EPOCH_MS", timestamp)
 217    if scale == exp.UnixToTime.MICROS:
 218        return self.func("MAKE_TIMESTAMP", timestamp)
 219
 220    return self.func("TO_TIMESTAMP", exp.Div(this=timestamp, expression=exp.func("POW", 10, scale)))
 221
 222
 223WRAPPED_JSON_EXTRACT_EXPRESSIONS = (exp.Binary, exp.Bracket, exp.In)
 224
 225
 226def _arrow_json_extract_sql(self: DuckDB.Generator, expression: JSON_EXTRACT_TYPE) -> str:
 227    arrow_sql = arrow_json_extract_sql(self, expression)
 228    if not expression.same_parent and isinstance(
 229        expression.parent, WRAPPED_JSON_EXTRACT_EXPRESSIONS
 230    ):
 231        arrow_sql = self.wrap(arrow_sql)
 232    return arrow_sql
 233
 234
 235def _implicit_datetime_cast(
 236    arg: t.Optional[exp.Expression], type: exp.DataType.Type = exp.DataType.Type.DATE
 237) -> t.Optional[exp.Expression]:
 238    return exp.cast(arg, type) if isinstance(arg, exp.Literal) else arg
 239
 240
 241def _date_diff_sql(self: DuckDB.Generator, expression: exp.DateDiff) -> str:
 242    this = _implicit_datetime_cast(expression.this)
 243    expr = _implicit_datetime_cast(expression.expression)
 244
 245    return self.func("DATE_DIFF", unit_to_str(expression), expr, this)
 246
 247
 248def _generate_datetime_array_sql(
 249    self: DuckDB.Generator, expression: t.Union[exp.GenerateDateArray, exp.GenerateTimestampArray]
 250) -> str:
 251    is_generate_date_array = isinstance(expression, exp.GenerateDateArray)
 252
 253    type = exp.DataType.Type.DATE if is_generate_date_array else exp.DataType.Type.TIMESTAMP
 254    start = _implicit_datetime_cast(expression.args.get("start"), type=type)
 255    end = _implicit_datetime_cast(expression.args.get("end"), type=type)
 256
 257    # BQ's GENERATE_DATE_ARRAY & GENERATE_TIMESTAMP_ARRAY are transformed to DuckDB'S GENERATE_SERIES
 258    gen_series: t.Union[exp.GenerateSeries, exp.Cast] = exp.GenerateSeries(
 259        start=start, end=end, step=expression.args.get("step")
 260    )
 261
 262    if is_generate_date_array:
 263        # The GENERATE_SERIES result type is TIMESTAMP array, so to match BQ's semantics for
 264        # GENERATE_DATE_ARRAY we must cast it back to DATE array
 265        gen_series = exp.cast(gen_series, exp.DataType.build("ARRAY<DATE>"))
 266
 267    return self.sql(gen_series)
 268
 269
 270def _json_extract_value_array_sql(
 271    self: DuckDB.Generator, expression: exp.JSONValueArray | exp.JSONExtractArray
 272) -> str:
 273    json_extract = exp.JSONExtract(this=expression.this, expression=expression.expression)
 274    data_type = "ARRAY<STRING>" if isinstance(expression, exp.JSONValueArray) else "ARRAY<JSON>"
 275    return self.sql(exp.cast(json_extract, to=exp.DataType.build(data_type)))
 276
 277
 278class DuckDB(Dialect):
 279    NULL_ORDERING = "nulls_are_last"
 280    SUPPORTS_USER_DEFINED_TYPES = True
 281    SAFE_DIVISION = True
 282    INDEX_OFFSET = 1
 283    CONCAT_COALESCE = True
 284    SUPPORTS_ORDER_BY_ALL = True
 285    SUPPORTS_FIXED_SIZE_ARRAYS = True
 286    STRICT_JSON_PATH_SYNTAX = False
 287    NUMBERS_CAN_BE_UNDERSCORE_SEPARATED = True
 288
 289    # https://duckdb.org/docs/sql/introduction.html#creating-a-new-table
 290    NORMALIZATION_STRATEGY = NormalizationStrategy.CASE_INSENSITIVE
 291
 292    def to_json_path(self, path: t.Optional[exp.Expression]) -> t.Optional[exp.Expression]:
 293        if isinstance(path, exp.Literal):
 294            # DuckDB also supports the JSON pointer syntax, where every path starts with a `/`.
 295            # Additionally, it allows accessing the back of lists using the `[#-i]` syntax.
 296            # This check ensures we'll avoid trying to parse these as JSON paths, which can
 297            # either result in a noisy warning or in an invalid representation of the path.
 298            path_text = path.name
 299            if path_text.startswith("/") or "[#" in path_text:
 300                return path
 301
 302        return super().to_json_path(path)
 303
 304    class Tokenizer(tokens.Tokenizer):
 305        BYTE_STRINGS = [("e'", "'"), ("E'", "'")]
 306        HEREDOC_STRINGS = ["$"]
 307
 308        HEREDOC_TAG_IS_IDENTIFIER = True
 309        HEREDOC_STRING_ALTERNATIVE = TokenType.PARAMETER
 310
 311        KEYWORDS = {
 312            **tokens.Tokenizer.KEYWORDS,
 313            "//": TokenType.DIV,
 314            "**": TokenType.DSTAR,
 315            "^@": TokenType.CARET_AT,
 316            "@>": TokenType.AT_GT,
 317            "<@": TokenType.LT_AT,
 318            "ATTACH": TokenType.ATTACH,
 319            "BINARY": TokenType.VARBINARY,
 320            "BITSTRING": TokenType.BIT,
 321            "BPCHAR": TokenType.TEXT,
 322            "CHAR": TokenType.TEXT,
 323            "CHARACTER VARYING": TokenType.TEXT,
 324            "DETACH": TokenType.DETACH,
 325            "EXCLUDE": TokenType.EXCEPT,
 326            "LOGICAL": TokenType.BOOLEAN,
 327            "ONLY": TokenType.ONLY,
 328            "PIVOT_WIDER": TokenType.PIVOT,
 329            "POSITIONAL": TokenType.POSITIONAL,
 330            "SIGNED": TokenType.INT,
 331            "STRING": TokenType.TEXT,
 332            "SUMMARIZE": TokenType.SUMMARIZE,
 333            "TIMESTAMP_S": TokenType.TIMESTAMP_S,
 334            "TIMESTAMP_MS": TokenType.TIMESTAMP_MS,
 335            "TIMESTAMP_NS": TokenType.TIMESTAMP_NS,
 336            "TIMESTAMP_US": TokenType.TIMESTAMP,
 337            "UBIGINT": TokenType.UBIGINT,
 338            "UINTEGER": TokenType.UINT,
 339            "USMALLINT": TokenType.USMALLINT,
 340            "UTINYINT": TokenType.UTINYINT,
 341            "VARCHAR": TokenType.TEXT,
 342        }
 343        KEYWORDS.pop("/*+")
 344
 345        SINGLE_TOKENS = {
 346            **tokens.Tokenizer.SINGLE_TOKENS,
 347            "$": TokenType.PARAMETER,
 348        }
 349
 350        COMMANDS = tokens.Tokenizer.COMMANDS - {TokenType.SHOW}
 351
 352    class Parser(parser.Parser):
 353        BITWISE = {
 354            **parser.Parser.BITWISE,
 355            TokenType.TILDA: exp.RegexpLike,
 356        }
 357        BITWISE.pop(TokenType.CARET)
 358
 359        RANGE_PARSERS = {
 360            **parser.Parser.RANGE_PARSERS,
 361            TokenType.DAMP: binary_range_parser(exp.ArrayOverlaps),
 362            TokenType.CARET_AT: binary_range_parser(exp.StartsWith),
 363        }
 364
 365        EXPONENT = {
 366            **parser.Parser.EXPONENT,
 367            TokenType.CARET: exp.Pow,
 368            TokenType.DSTAR: exp.Pow,
 369        }
 370
 371        FUNCTIONS_WITH_ALIASED_ARGS = {*parser.Parser.FUNCTIONS_WITH_ALIASED_ARGS, "STRUCT_PACK"}
 372
 373        SHOW_PARSERS = {
 374            "TABLES": _show_parser("TABLES"),
 375            "ALL TABLES": _show_parser("ALL TABLES"),
 376        }
 377
 378        FUNCTIONS = {
 379            **parser.Parser.FUNCTIONS,
 380            "ARRAY_REVERSE_SORT": _build_sort_array_desc,
 381            "ARRAY_SORT": exp.SortArray.from_arg_list,
 382            "DATEDIFF": _build_date_diff,
 383            "DATE_DIFF": _build_date_diff,
 384            "DATE_TRUNC": date_trunc_to_time,
 385            "DATETRUNC": date_trunc_to_time,
 386            "DECODE": lambda args: exp.Decode(
 387                this=seq_get(args, 0), charset=exp.Literal.string("utf-8")
 388            ),
 389            "EDITDIST3": exp.Levenshtein.from_arg_list,
 390            "ENCODE": lambda args: exp.Encode(
 391                this=seq_get(args, 0), charset=exp.Literal.string("utf-8")
 392            ),
 393            "EPOCH": exp.TimeToUnix.from_arg_list,
 394            "EPOCH_MS": lambda args: exp.UnixToTime(
 395                this=seq_get(args, 0), scale=exp.UnixToTime.MILLIS
 396            ),
 397            "GENERATE_SERIES": _build_generate_series(),
 398            "JSON": exp.ParseJSON.from_arg_list,
 399            "JSON_EXTRACT_PATH": parser.build_extract_json_with_path(exp.JSONExtract),
 400            "JSON_EXTRACT_STRING": parser.build_extract_json_with_path(exp.JSONExtractScalar),
 401            "LIST_HAS": exp.ArrayContains.from_arg_list,
 402            "LIST_REVERSE_SORT": _build_sort_array_desc,
 403            "LIST_SORT": exp.SortArray.from_arg_list,
 404            "LIST_VALUE": lambda args: exp.Array(expressions=args),
 405            "MAKE_TIME": exp.TimeFromParts.from_arg_list,
 406            "MAKE_TIMESTAMP": _build_make_timestamp,
 407            "QUANTILE_CONT": exp.PercentileCont.from_arg_list,
 408            "QUANTILE_DISC": exp.PercentileDisc.from_arg_list,
 409            "RANGE": _build_generate_series(end_exclusive=True),
 410            "REGEXP_EXTRACT": build_regexp_extract(exp.RegexpExtract),
 411            "REGEXP_EXTRACT_ALL": build_regexp_extract(exp.RegexpExtractAll),
 412            "REGEXP_MATCHES": exp.RegexpLike.from_arg_list,
 413            "REGEXP_REPLACE": lambda args: exp.RegexpReplace(
 414                this=seq_get(args, 0),
 415                expression=seq_get(args, 1),
 416                replacement=seq_get(args, 2),
 417                modifiers=seq_get(args, 3),
 418            ),
 419            "SHA256": lambda args: exp.SHA2(this=seq_get(args, 0), length=exp.Literal.number(256)),
 420            "STRFTIME": build_formatted_time(exp.TimeToStr, "duckdb"),
 421            "STRING_SPLIT": exp.Split.from_arg_list,
 422            "STRING_SPLIT_REGEX": exp.RegexpSplit.from_arg_list,
 423            "STRING_TO_ARRAY": exp.Split.from_arg_list,
 424            "STRPTIME": build_formatted_time(exp.StrToTime, "duckdb"),
 425            "STRUCT_PACK": exp.Struct.from_arg_list,
 426            "STR_SPLIT": exp.Split.from_arg_list,
 427            "STR_SPLIT_REGEX": exp.RegexpSplit.from_arg_list,
 428            "TIME_BUCKET": exp.DateBin.from_arg_list,
 429            "TO_TIMESTAMP": exp.UnixToTime.from_arg_list,
 430            "UNNEST": exp.Explode.from_arg_list,
 431            "XOR": binary_from_function(exp.BitwiseXor),
 432        }
 433
 434        FUNCTIONS.pop("DATE_SUB")
 435        FUNCTIONS.pop("GLOB")
 436
 437        FUNCTION_PARSERS = {
 438            **parser.Parser.FUNCTION_PARSERS,
 439            **dict.fromkeys(
 440                ("GROUP_CONCAT", "LISTAGG", "STRINGAGG"), lambda self: self._parse_string_agg()
 441            ),
 442        }
 443        FUNCTION_PARSERS.pop("DECODE")
 444
 445        NO_PAREN_FUNCTION_PARSERS = {
 446            **parser.Parser.NO_PAREN_FUNCTION_PARSERS,
 447            "MAP": lambda self: self._parse_map(),
 448            "@": lambda self: exp.Abs(this=self._parse_bitwise()),
 449        }
 450
 451        TABLE_ALIAS_TOKENS = parser.Parser.TABLE_ALIAS_TOKENS - {
 452            TokenType.SEMI,
 453            TokenType.ANTI,
 454        }
 455
 456        PLACEHOLDER_PARSERS = {
 457            **parser.Parser.PLACEHOLDER_PARSERS,
 458            TokenType.PARAMETER: lambda self: (
 459                self.expression(exp.Placeholder, this=self._prev.text)
 460                if self._match(TokenType.NUMBER) or self._match_set(self.ID_VAR_TOKENS)
 461                else None
 462            ),
 463        }
 464
 465        TYPE_CONVERTERS = {
 466            # https://duckdb.org/docs/sql/data_types/numeric
 467            exp.DataType.Type.DECIMAL: build_default_decimal_type(precision=18, scale=3),
 468            # https://duckdb.org/docs/sql/data_types/text
 469            exp.DataType.Type.TEXT: lambda dtype: exp.DataType.build("TEXT"),
 470        }
 471
 472        STATEMENT_PARSERS = {
 473            **parser.Parser.STATEMENT_PARSERS,
 474            TokenType.ATTACH: lambda self: self._parse_attach_detach(),
 475            TokenType.DETACH: lambda self: self._parse_attach_detach(is_attach=False),
 476            TokenType.SHOW: lambda self: self._parse_show(),
 477        }
 478
 479        def _parse_expression(self) -> t.Optional[exp.Expression]:
 480            # DuckDB supports prefix aliases, e.g. foo: 1
 481            if self._next and self._next.token_type == TokenType.COLON:
 482                alias = self._parse_id_var(tokens=self.ALIAS_TOKENS)
 483                self._match(TokenType.COLON)
 484                comments = self._prev_comments or []
 485
 486                this = self._parse_assignment()
 487                if isinstance(this, exp.Expression):
 488                    # Moves the comment next to the alias in `alias: expr /* comment */`
 489                    comments += this.pop_comments() or []
 490
 491                return self.expression(exp.Alias, comments=comments, this=this, alias=alias)
 492
 493            return super()._parse_expression()
 494
 495        def _parse_table(
 496            self,
 497            schema: bool = False,
 498            joins: bool = False,
 499            alias_tokens: t.Optional[t.Collection[TokenType]] = None,
 500            parse_bracket: bool = False,
 501            is_db_reference: bool = False,
 502            parse_partition: bool = False,
 503        ) -> t.Optional[exp.Expression]:
 504            # DuckDB supports prefix aliases, e.g. FROM foo: bar
 505            if self._next and self._next.token_type == TokenType.COLON:
 506                alias = self._parse_table_alias(
 507                    alias_tokens=alias_tokens or self.TABLE_ALIAS_TOKENS
 508                )
 509                self._match(TokenType.COLON)
 510                comments = self._prev_comments or []
 511            else:
 512                alias = None
 513                comments = []
 514
 515            table = super()._parse_table(
 516                schema=schema,
 517                joins=joins,
 518                alias_tokens=alias_tokens,
 519                parse_bracket=parse_bracket,
 520                is_db_reference=is_db_reference,
 521                parse_partition=parse_partition,
 522            )
 523            if isinstance(table, exp.Expression) and isinstance(alias, exp.TableAlias):
 524                # Moves the comment next to the alias in `alias: table /* comment */`
 525                comments += table.pop_comments() or []
 526                alias.comments = alias.pop_comments() + comments
 527                table.set("alias", alias)
 528
 529            return table
 530
 531        def _parse_table_sample(self, as_modifier: bool = False) -> t.Optional[exp.TableSample]:
 532            # https://duckdb.org/docs/sql/samples.html
 533            sample = super()._parse_table_sample(as_modifier=as_modifier)
 534            if sample and not sample.args.get("method"):
 535                if sample.args.get("size"):
 536                    sample.set("method", exp.var("RESERVOIR"))
 537                else:
 538                    sample.set("method", exp.var("SYSTEM"))
 539
 540            return sample
 541
 542        def _parse_bracket(
 543            self, this: t.Optional[exp.Expression] = None
 544        ) -> t.Optional[exp.Expression]:
 545            bracket = super()._parse_bracket(this)
 546
 547            if self.dialect.version < Version("1.2.0") and isinstance(bracket, exp.Bracket):
 548                # https://duckdb.org/2025/02/05/announcing-duckdb-120.html#breaking-changes
 549                bracket.set("returns_list_for_maps", True)
 550
 551            return bracket
 552
 553        def _parse_map(self) -> exp.ToMap | exp.Map:
 554            if self._match(TokenType.L_BRACE, advance=False):
 555                return self.expression(exp.ToMap, this=self._parse_bracket())
 556
 557            args = self._parse_wrapped_csv(self._parse_assignment)
 558            return self.expression(exp.Map, keys=seq_get(args, 0), values=seq_get(args, 1))
 559
 560        def _parse_struct_types(self, type_required: bool = False) -> t.Optional[exp.Expression]:
 561            return self._parse_field_def()
 562
 563        def _pivot_column_names(self, aggregations: t.List[exp.Expression]) -> t.List[str]:
 564            if len(aggregations) == 1:
 565                return super()._pivot_column_names(aggregations)
 566            return pivot_column_names(aggregations, dialect="duckdb")
 567
 568        def _parse_attach_detach(self, is_attach=True) -> exp.Attach | exp.Detach:
 569            def _parse_attach_option() -> exp.AttachOption:
 570                return self.expression(
 571                    exp.AttachOption,
 572                    this=self._parse_var(any_token=True),
 573                    expression=self._parse_field(any_token=True),
 574                )
 575
 576            self._match(TokenType.DATABASE)
 577            exists = self._parse_exists(not_=is_attach)
 578            this = self._parse_alias(self._parse_primary_or_var(), explicit=True)
 579
 580            if self._match(TokenType.L_PAREN, advance=False):
 581                expressions = self._parse_wrapped_csv(_parse_attach_option)
 582            else:
 583                expressions = None
 584
 585            return (
 586                self.expression(exp.Attach, this=this, exists=exists, expressions=expressions)
 587                if is_attach
 588                else self.expression(exp.Detach, this=this, exists=exists)
 589            )
 590
 591        def _parse_show_duckdb(self, this: str) -> exp.Show:
 592            return self.expression(exp.Show, this=this)
 593
 594    class Generator(generator.Generator):
 595        PARAMETER_TOKEN = "$"
 596        NAMED_PLACEHOLDER_TOKEN = "$"
 597        JOIN_HINTS = False
 598        TABLE_HINTS = False
 599        QUERY_HINTS = False
 600        LIMIT_FETCH = "LIMIT"
 601        STRUCT_DELIMITER = ("(", ")")
 602        RENAME_TABLE_WITH_DB = False
 603        NVL2_SUPPORTED = False
 604        SEMI_ANTI_JOIN_WITH_SIDE = False
 605        TABLESAMPLE_KEYWORDS = "USING SAMPLE"
 606        TABLESAMPLE_SEED_KEYWORD = "REPEATABLE"
 607        LAST_DAY_SUPPORTS_DATE_PART = False
 608        JSON_KEY_VALUE_PAIR_SEP = ","
 609        IGNORE_NULLS_IN_FUNC = True
 610        JSON_PATH_BRACKETED_KEY_SUPPORTED = False
 611        SUPPORTS_CREATE_TABLE_LIKE = False
 612        MULTI_ARG_DISTINCT = False
 613        CAN_IMPLEMENT_ARRAY_ANY = True
 614        SUPPORTS_TO_NUMBER = False
 615        COPY_HAS_INTO_KEYWORD = False
 616        STAR_EXCEPT = "EXCLUDE"
 617        PAD_FILL_PATTERN_IS_REQUIRED = True
 618        ARRAY_CONCAT_IS_VAR_LEN = False
 619        ARRAY_SIZE_DIM_REQUIRED = False
 620
 621        TRANSFORMS = {
 622            **generator.Generator.TRANSFORMS,
 623            exp.ApproxDistinct: approx_count_distinct_sql,
 624            exp.Array: inline_array_unless_query,
 625            exp.ArrayFilter: rename_func("LIST_FILTER"),
 626            exp.ArraySort: _array_sort_sql,
 627            exp.ArraySum: rename_func("LIST_SUM"),
 628            exp.BitwiseXor: rename_func("XOR"),
 629            exp.CommentColumnConstraint: no_comment_column_constraint_sql,
 630            exp.CurrentDate: lambda *_: "CURRENT_DATE",
 631            exp.CurrentTime: lambda *_: "CURRENT_TIME",
 632            exp.CurrentTimestamp: lambda *_: "CURRENT_TIMESTAMP",
 633            exp.DayOfMonth: rename_func("DAYOFMONTH"),
 634            exp.DayOfWeek: rename_func("DAYOFWEEK"),
 635            exp.DayOfWeekIso: rename_func("ISODOW"),
 636            exp.DayOfYear: rename_func("DAYOFYEAR"),
 637            exp.DataType: _datatype_sql,
 638            exp.Date: _date_sql,
 639            exp.DateAdd: _date_delta_sql,
 640            exp.DateFromParts: rename_func("MAKE_DATE"),
 641            exp.DateSub: _date_delta_sql,
 642            exp.DateDiff: _date_diff_sql,
 643            exp.DateStrToDate: datestrtodate_sql,
 644            exp.Datetime: no_datetime_sql,
 645            exp.DatetimeSub: _date_delta_sql,
 646            exp.DatetimeAdd: _date_delta_sql,
 647            exp.DateToDi: lambda self,
 648            e: f"CAST(STRFTIME({self.sql(e, 'this')}, {DuckDB.DATEINT_FORMAT}) AS INT)",
 649            exp.Decode: lambda self, e: encode_decode_sql(self, e, "DECODE", replace=False),
 650            exp.DiToDate: lambda self,
 651            e: f"CAST(STRPTIME(CAST({self.sql(e, 'this')} AS TEXT), {DuckDB.DATEINT_FORMAT}) AS DATE)",
 652            exp.Encode: lambda self, e: encode_decode_sql(self, e, "ENCODE", replace=False),
 653            exp.GenerateDateArray: _generate_datetime_array_sql,
 654            exp.GenerateTimestampArray: _generate_datetime_array_sql,
 655            exp.GroupConcat: lambda self, e: groupconcat_sql(self, e, within_group=False),
 656            exp.HexString: lambda self, e: self.hexstring_sql(e, binary_function_repr="FROM_HEX"),
 657            exp.Explode: rename_func("UNNEST"),
 658            exp.IntDiv: lambda self, e: self.binary(e, "//"),
 659            exp.IsInf: rename_func("ISINF"),
 660            exp.IsNan: rename_func("ISNAN"),
 661            exp.JSONBExists: rename_func("JSON_EXISTS"),
 662            exp.JSONExtract: _arrow_json_extract_sql,
 663            exp.JSONExtractArray: _json_extract_value_array_sql,
 664            exp.JSONExtractScalar: _arrow_json_extract_sql,
 665            exp.JSONFormat: _json_format_sql,
 666            exp.JSONValueArray: _json_extract_value_array_sql,
 667            exp.Lateral: explode_to_unnest_sql,
 668            exp.LogicalOr: rename_func("BOOL_OR"),
 669            exp.LogicalAnd: rename_func("BOOL_AND"),
 670            exp.MakeInterval: lambda self, e: no_make_interval_sql(self, e, sep=" "),
 671            exp.MD5Digest: lambda self, e: self.func("UNHEX", self.func("MD5", e.this)),
 672            exp.MonthsBetween: lambda self, e: self.func(
 673                "DATEDIFF",
 674                "'month'",
 675                exp.cast(e.expression, exp.DataType.Type.TIMESTAMP, copy=True),
 676                exp.cast(e.this, exp.DataType.Type.TIMESTAMP, copy=True),
 677            ),
 678            exp.PercentileCont: rename_func("QUANTILE_CONT"),
 679            exp.PercentileDisc: rename_func("QUANTILE_DISC"),
 680            # DuckDB doesn't allow qualified columns inside of PIVOT expressions.
 681            # See: https://github.com/duckdb/duckdb/blob/671faf92411182f81dce42ac43de8bfb05d9909e/src/planner/binder/tableref/bind_pivot.cpp#L61-L62
 682            exp.Pivot: transforms.preprocess([transforms.unqualify_columns]),
 683            exp.RegexpReplace: lambda self, e: self.func(
 684                "REGEXP_REPLACE",
 685                e.this,
 686                e.expression,
 687                e.args.get("replacement"),
 688                e.args.get("modifiers"),
 689            ),
 690            exp.RegexpLike: rename_func("REGEXP_MATCHES"),
 691            exp.RegexpILike: lambda self, e: self.func(
 692                "REGEXP_MATCHES", e.this, e.expression, exp.Literal.string("i")
 693            ),
 694            exp.RegexpSplit: rename_func("STR_SPLIT_REGEX"),
 695            exp.Return: lambda self, e: self.sql(e, "this"),
 696            exp.ReturnsProperty: lambda self, e: "TABLE" if isinstance(e.this, exp.Schema) else "",
 697            exp.Rand: rename_func("RANDOM"),
 698            exp.SHA: rename_func("SHA1"),
 699            exp.SHA2: sha256_sql,
 700            exp.Split: rename_func("STR_SPLIT"),
 701            exp.SortArray: _sort_array_sql,
 702            exp.StrPosition: strposition_sql,
 703            exp.StrToUnix: lambda self, e: self.func(
 704                "EPOCH", self.func("STRPTIME", e.this, self.format_time(e))
 705            ),
 706            exp.Struct: _struct_sql,
 707            exp.Transform: rename_func("LIST_TRANSFORM"),
 708            exp.TimeAdd: _date_delta_sql,
 709            exp.Time: no_time_sql,
 710            exp.TimeDiff: _timediff_sql,
 711            exp.Timestamp: no_timestamp_sql,
 712            exp.TimestampDiff: lambda self, e: self.func(
 713                "DATE_DIFF", exp.Literal.string(e.unit), e.expression, e.this
 714            ),
 715            exp.TimestampTrunc: timestamptrunc_sql(),
 716            exp.TimeStrToDate: lambda self, e: self.sql(exp.cast(e.this, exp.DataType.Type.DATE)),
 717            exp.TimeStrToTime: timestrtotime_sql,
 718            exp.TimeStrToUnix: lambda self, e: self.func(
 719                "EPOCH", exp.cast(e.this, exp.DataType.Type.TIMESTAMP)
 720            ),
 721            exp.TimeToStr: lambda self, e: self.func("STRFTIME", e.this, self.format_time(e)),
 722            exp.TimeToUnix: rename_func("EPOCH"),
 723            exp.TsOrDiToDi: lambda self,
 724            e: f"CAST(SUBSTR(REPLACE(CAST({self.sql(e, 'this')} AS TEXT), '-', ''), 1, 8) AS INT)",
 725            exp.TsOrDsAdd: _date_delta_sql,
 726            exp.TsOrDsDiff: lambda self, e: self.func(
 727                "DATE_DIFF",
 728                f"'{e.args.get('unit') or 'DAY'}'",
 729                exp.cast(e.expression, exp.DataType.Type.TIMESTAMP),
 730                exp.cast(e.this, exp.DataType.Type.TIMESTAMP),
 731            ),
 732            exp.UnixToStr: lambda self, e: self.func(
 733                "STRFTIME", self.func("TO_TIMESTAMP", e.this), self.format_time(e)
 734            ),
 735            exp.DatetimeTrunc: lambda self, e: self.func(
 736                "DATE_TRUNC", unit_to_str(e), exp.cast(e.this, exp.DataType.Type.DATETIME)
 737            ),
 738            exp.UnixToTime: _unix_to_time_sql,
 739            exp.UnixToTimeStr: lambda self, e: f"CAST(TO_TIMESTAMP({self.sql(e, 'this')}) AS TEXT)",
 740            exp.VariancePop: rename_func("VAR_POP"),
 741            exp.WeekOfYear: rename_func("WEEKOFYEAR"),
 742            exp.Xor: bool_xor_sql,
 743            exp.Levenshtein: unsupported_args("ins_cost", "del_cost", "sub_cost", "max_dist")(
 744                rename_func("LEVENSHTEIN")
 745            ),
 746            exp.JSONObjectAgg: rename_func("JSON_GROUP_OBJECT"),
 747            exp.JSONBObjectAgg: rename_func("JSON_GROUP_OBJECT"),
 748            exp.DateBin: rename_func("TIME_BUCKET"),
 749        }
 750
 751        SUPPORTED_JSON_PATH_PARTS = {
 752            exp.JSONPathKey,
 753            exp.JSONPathRoot,
 754            exp.JSONPathSubscript,
 755            exp.JSONPathWildcard,
 756        }
 757
 758        TYPE_MAPPING = {
 759            **generator.Generator.TYPE_MAPPING,
 760            exp.DataType.Type.BINARY: "BLOB",
 761            exp.DataType.Type.BPCHAR: "TEXT",
 762            exp.DataType.Type.CHAR: "TEXT",
 763            exp.DataType.Type.DATETIME: "TIMESTAMP",
 764            exp.DataType.Type.FLOAT: "REAL",
 765            exp.DataType.Type.JSONB: "JSON",
 766            exp.DataType.Type.NCHAR: "TEXT",
 767            exp.DataType.Type.NVARCHAR: "TEXT",
 768            exp.DataType.Type.UINT: "UINTEGER",
 769            exp.DataType.Type.VARBINARY: "BLOB",
 770            exp.DataType.Type.ROWVERSION: "BLOB",
 771            exp.DataType.Type.VARCHAR: "TEXT",
 772            exp.DataType.Type.TIMESTAMPNTZ: "TIMESTAMP",
 773            exp.DataType.Type.TIMESTAMP_S: "TIMESTAMP_S",
 774            exp.DataType.Type.TIMESTAMP_MS: "TIMESTAMP_MS",
 775            exp.DataType.Type.TIMESTAMP_NS: "TIMESTAMP_NS",
 776        }
 777
 778        # https://github.com/duckdb/duckdb/blob/ff7f24fd8e3128d94371827523dae85ebaf58713/third_party/libpg_query/grammar/keywords/reserved_keywords.list#L1-L77
 779        RESERVED_KEYWORDS = {
 780            "array",
 781            "analyse",
 782            "union",
 783            "all",
 784            "when",
 785            "in_p",
 786            "default",
 787            "create_p",
 788            "window",
 789            "asymmetric",
 790            "to",
 791            "else",
 792            "localtime",
 793            "from",
 794            "end_p",
 795            "select",
 796            "current_date",
 797            "foreign",
 798            "with",
 799            "grant",
 800            "session_user",
 801            "or",
 802            "except",
 803            "references",
 804            "fetch",
 805            "limit",
 806            "group_p",
 807            "leading",
 808            "into",
 809            "collate",
 810            "offset",
 811            "do",
 812            "then",
 813            "localtimestamp",
 814            "check_p",
 815            "lateral_p",
 816            "current_role",
 817            "where",
 818            "asc_p",
 819            "placing",
 820            "desc_p",
 821            "user",
 822            "unique",
 823            "initially",
 824            "column",
 825            "both",
 826            "some",
 827            "as",
 828            "any",
 829            "only",
 830            "deferrable",
 831            "null_p",
 832            "current_time",
 833            "true_p",
 834            "table",
 835            "case",
 836            "trailing",
 837            "variadic",
 838            "for",
 839            "on",
 840            "distinct",
 841            "false_p",
 842            "not",
 843            "constraint",
 844            "current_timestamp",
 845            "returning",
 846            "primary",
 847            "intersect",
 848            "having",
 849            "analyze",
 850            "current_user",
 851            "and",
 852            "cast",
 853            "symmetric",
 854            "using",
 855            "order",
 856            "current_catalog",
 857        }
 858
 859        UNWRAPPED_INTERVAL_VALUES = (exp.Literal, exp.Paren)
 860
 861        # DuckDB doesn't generally support CREATE TABLE .. properties
 862        # https://duckdb.org/docs/sql/statements/create_table.html
 863        PROPERTIES_LOCATION = {
 864            prop: exp.Properties.Location.UNSUPPORTED
 865            for prop in generator.Generator.PROPERTIES_LOCATION
 866        }
 867
 868        # There are a few exceptions (e.g. temporary tables) which are supported or
 869        # can be transpiled to DuckDB, so we explicitly override them accordingly
 870        PROPERTIES_LOCATION[exp.LikeProperty] = exp.Properties.Location.POST_SCHEMA
 871        PROPERTIES_LOCATION[exp.TemporaryProperty] = exp.Properties.Location.POST_CREATE
 872        PROPERTIES_LOCATION[exp.ReturnsProperty] = exp.Properties.Location.POST_ALIAS
 873
 874        IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS = (
 875            exp.FirstValue,
 876            exp.Lag,
 877            exp.LastValue,
 878            exp.Lead,
 879            exp.NthValue,
 880        )
 881
 882        def show_sql(self, expression: exp.Show) -> str:
 883            return f"SHOW {expression.name}"
 884
 885        def fromiso8601timestamp_sql(self, expression: exp.FromISO8601Timestamp) -> str:
 886            return self.sql(exp.cast(expression.this, exp.DataType.Type.TIMESTAMPTZ))
 887
 888        def strtotime_sql(self, expression: exp.StrToTime) -> str:
 889            if expression.args.get("safe"):
 890                formatted_time = self.format_time(expression)
 891                return f"CAST({self.func('TRY_STRPTIME', expression.this, formatted_time)} AS TIMESTAMP)"
 892            return str_to_time_sql(self, expression)
 893
 894        def strtodate_sql(self, expression: exp.StrToDate) -> str:
 895            if expression.args.get("safe"):
 896                formatted_time = self.format_time(expression)
 897                return f"CAST({self.func('TRY_STRPTIME', expression.this, formatted_time)} AS DATE)"
 898            return f"CAST({str_to_time_sql(self, expression)} AS DATE)"
 899
 900        def parsejson_sql(self, expression: exp.ParseJSON) -> str:
 901            arg = expression.this
 902            if expression.args.get("safe"):
 903                return self.sql(exp.case().when(exp.func("json_valid", arg), arg).else_(exp.null()))
 904            return self.func("JSON", arg)
 905
 906        def timefromparts_sql(self, expression: exp.TimeFromParts) -> str:
 907            nano = expression.args.get("nano")
 908            if nano is not None:
 909                expression.set(
 910                    "sec", expression.args["sec"] + nano.pop() / exp.Literal.number(1000000000.0)
 911                )
 912
 913            return rename_func("MAKE_TIME")(self, expression)
 914
 915        def timestampfromparts_sql(self, expression: exp.TimestampFromParts) -> str:
 916            sec = expression.args["sec"]
 917
 918            milli = expression.args.get("milli")
 919            if milli is not None:
 920                sec += milli.pop() / exp.Literal.number(1000.0)
 921
 922            nano = expression.args.get("nano")
 923            if nano is not None:
 924                sec += nano.pop() / exp.Literal.number(1000000000.0)
 925
 926            if milli or nano:
 927                expression.set("sec", sec)
 928
 929            return rename_func("MAKE_TIMESTAMP")(self, expression)
 930
 931        def tablesample_sql(
 932            self,
 933            expression: exp.TableSample,
 934            tablesample_keyword: t.Optional[str] = None,
 935        ) -> str:
 936            if not isinstance(expression.parent, exp.Select):
 937                # This sample clause only applies to a single source, not the entire resulting relation
 938                tablesample_keyword = "TABLESAMPLE"
 939
 940            if expression.args.get("size"):
 941                method = expression.args.get("method")
 942                if method and method.name.upper() != "RESERVOIR":
 943                    self.unsupported(
 944                        f"Sampling method {method} is not supported with a discrete sample count, "
 945                        "defaulting to reservoir sampling"
 946                    )
 947                    expression.set("method", exp.var("RESERVOIR"))
 948
 949            return super().tablesample_sql(expression, tablesample_keyword=tablesample_keyword)
 950
 951        def interval_sql(self, expression: exp.Interval) -> str:
 952            multiplier: t.Optional[int] = None
 953            unit = expression.text("unit").lower()
 954
 955            if unit.startswith("week"):
 956                multiplier = 7
 957            if unit.startswith("quarter"):
 958                multiplier = 90
 959
 960            if multiplier:
 961                return f"({multiplier} * {super().interval_sql(exp.Interval(this=expression.this, unit=exp.var('DAY')))})"
 962
 963            return super().interval_sql(expression)
 964
 965        def columndef_sql(self, expression: exp.ColumnDef, sep: str = " ") -> str:
 966            if isinstance(expression.parent, exp.UserDefinedFunction):
 967                return self.sql(expression, "this")
 968            return super().columndef_sql(expression, sep)
 969
 970        def join_sql(self, expression: exp.Join) -> str:
 971            if (
 972                expression.side == "LEFT"
 973                and not expression.args.get("on")
 974                and isinstance(expression.this, exp.Unnest)
 975            ):
 976                # Some dialects support `LEFT JOIN UNNEST(...)` without an explicit ON clause
 977                # DuckDB doesn't, but we can just add a dummy ON clause that is always true
 978                return super().join_sql(expression.on(exp.true()))
 979
 980            return super().join_sql(expression)
 981
 982        def generateseries_sql(self, expression: exp.GenerateSeries) -> str:
 983            # GENERATE_SERIES(a, b) -> [a, b], RANGE(a, b) -> [a, b)
 984            if expression.args.get("is_end_exclusive"):
 985                return rename_func("RANGE")(self, expression)
 986
 987            return self.function_fallback_sql(expression)
 988
 989        def countif_sql(self, expression: exp.CountIf) -> str:
 990            if self.dialect.version >= Version("1.2"):
 991                return self.function_fallback_sql(expression)
 992
 993            # https://github.com/tobymao/sqlglot/pull/4749
 994            return count_if_to_sum(self, expression)
 995
 996        def bracket_sql(self, expression: exp.Bracket) -> str:
 997            if self.dialect.version >= Version("1.2"):
 998                return super().bracket_sql(expression)
 999
1000            # https://duckdb.org/2025/02/05/announcing-duckdb-120.html#breaking-changes
1001            this = expression.this
1002            if isinstance(this, exp.Array):
1003                this.replace(exp.paren(this))
1004
1005            bracket = super().bracket_sql(expression)
1006
1007            if not expression.args.get("returns_list_for_maps"):
1008                if not this.type:
1009                    from sqlglot.optimizer.annotate_types import annotate_types
1010
1011                    this = annotate_types(this, dialect=self.dialect)
1012
1013                if this.is_type(exp.DataType.Type.MAP):
1014                    bracket = f"({bracket})[1]"
1015
1016            return bracket
1017
1018        def withingroup_sql(self, expression: exp.WithinGroup) -> str:
1019            expression_sql = self.sql(expression, "expression")
1020
1021            func = expression.this
1022            if isinstance(func, exp.PERCENTILES):
1023                # Make the order key the first arg and slide the fraction to the right
1024                # https://duckdb.org/docs/sql/aggregates#ordered-set-aggregate-functions
1025                order_col = expression.find(exp.Ordered)
1026                if order_col:
1027                    func.set("expression", func.this)
1028                    func.set("this", order_col.this)
1029
1030            this = self.sql(expression, "this").rstrip(")")
1031
1032            return f"{this}{expression_sql})"
1033
1034        def length_sql(self, expression: exp.Length) -> str:
1035            arg = expression.this
1036
1037            # Dialects like BQ and Snowflake also accept binary values as args, so
1038            # DDB will attempt to infer the type or resort to case/when resolution
1039            if not expression.args.get("binary") or arg.is_string:
1040                return self.func("LENGTH", arg)
1041
1042            if not arg.type:
1043                from sqlglot.optimizer.annotate_types import annotate_types
1044
1045                arg = annotate_types(arg, dialect=self.dialect)
1046
1047            if arg.is_type(*exp.DataType.TEXT_TYPES):
1048                return self.func("LENGTH", arg)
1049
1050            # We need these casts to make duckdb's static type checker happy
1051            blob = exp.cast(arg, exp.DataType.Type.VARBINARY)
1052            varchar = exp.cast(arg, exp.DataType.Type.VARCHAR)
1053
1054            case = (
1055                exp.case(self.func("TYPEOF", arg))
1056                .when("'BLOB'", self.func("OCTET_LENGTH", blob))
1057                .else_(
1058                    exp.Anonymous(this="LENGTH", expressions=[varchar])
1059                )  # anonymous to break length_sql recursion
1060            )
1061
1062            return self.sql(case)
1063
1064        def objectinsert_sql(self, expression: exp.ObjectInsert) -> str:
1065            this = expression.this
1066            key = expression.args.get("key")
1067            key_sql = key.name if isinstance(key, exp.Expression) else ""
1068            value_sql = self.sql(expression, "value")
1069
1070            kv_sql = f"{key_sql} := {value_sql}"
1071
1072            # If the input struct is empty e.g. transpiling OBJECT_INSERT(OBJECT_CONSTRUCT(), key, value) from Snowflake
1073            # then we can generate STRUCT_PACK which will build it since STRUCT_INSERT({}, key := value) is not valid DuckDB
1074            if isinstance(this, exp.Struct) and not this.expressions:
1075                return self.func("STRUCT_PACK", kv_sql)
1076
1077            return self.func("STRUCT_INSERT", this, kv_sql)
1078
1079        def unnest_sql(self, expression: exp.Unnest) -> str:
1080            explode_array = expression.args.get("explode_array")
1081            if explode_array:
1082                # In BigQuery, UNNESTing a nested array leads to explosion of the top-level array & struct
1083                # This is transpiled to DDB by transforming "FROM UNNEST(...)" to "FROM (SELECT UNNEST(..., max_depth => 2))"
1084                expression.expressions.append(
1085                    exp.Kwarg(this=exp.var("max_depth"), expression=exp.Literal.number(2))
1086                )
1087
1088                # If BQ's UNNEST is aliased, we transform it from a column alias to a table alias in DDB
1089                alias = expression.args.get("alias")
1090                if alias:
1091                    expression.set("alias", None)
1092                    alias = exp.TableAlias(this=seq_get(alias.args.get("columns"), 0))
1093
1094                unnest_sql = super().unnest_sql(expression)
1095                select = exp.Select(expressions=[unnest_sql]).subquery(alias)
1096                return self.sql(select)
1097
1098            return super().unnest_sql(expression)
1099
1100        def ignorenulls_sql(self, expression: exp.IgnoreNulls) -> str:
1101            if isinstance(expression.this, self.IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS):
1102                # DuckDB should render IGNORE NULLS only for the general-purpose
1103                # window functions that accept it e.g. FIRST_VALUE(... IGNORE NULLS) OVER (...)
1104                return super().ignorenulls_sql(expression)
1105
1106            self.unsupported("IGNORE NULLS is not supported for non-window functions.")
1107            return self.sql(expression, "this")
1108
1109        def respectnulls_sql(self, expression: exp.RespectNulls) -> str:
1110            if isinstance(expression.this, self.IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS):
1111                # DuckDB should render RESPECT NULLS only for the general-purpose
1112                # window functions that accept it e.g. FIRST_VALUE(... RESPECT NULLS) OVER (...)
1113                return super().respectnulls_sql(expression)
1114
1115            self.unsupported("RESPECT NULLS is not supported for non-window functions.")
1116            return self.sql(expression, "this")
1117
1118        def arraytostring_sql(self, expression: exp.ArrayToString) -> str:
1119            this = self.sql(expression, "this")
1120            null_text = self.sql(expression, "null")
1121
1122            if null_text:
1123                this = f"LIST_TRANSFORM({this}, x -> COALESCE(x, {null_text}))"
1124
1125            return self.func("ARRAY_TO_STRING", this, expression.expression)
1126
1127        @unsupported_args("position", "occurrence")
1128        def regexpextract_sql(self, expression: exp.RegexpExtract) -> str:
1129            group = expression.args.get("group")
1130            params = expression.args.get("parameters")
1131
1132            # Do not render group if there is no following argument,
1133            # and it's the default value for this dialect
1134            if (
1135                not params
1136                and group
1137                and group.name == str(self.dialect.REGEXP_EXTRACT_DEFAULT_GROUP)
1138            ):
1139                group = None
1140            return self.func(
1141                "REGEXP_EXTRACT", expression.this, expression.expression, group, params
1142            )
1143
1144        @unsupported_args("culture")
1145        def numbertostr_sql(self, expression: exp.NumberToStr) -> str:
1146            fmt = expression.args.get("format")
1147            if fmt and fmt.is_int:
1148                return self.func("FORMAT", f"'{{:,.{fmt.name}f}}'", expression.this)
1149
1150            self.unsupported("Only integer formats are supported by NumberToStr")
1151            return self.function_fallback_sql(expression)
1152
1153        def autoincrementcolumnconstraint_sql(self, _) -> str:
1154            self.unsupported("The AUTOINCREMENT column constraint is not supported by DuckDB")
1155            return ""