sqlglot.generators.clickhouse

  1from __future__ import annotations
  2
  3import datetime
  4import typing as t
  5
  6from sqlglot import exp, generator
  7from sqlglot.dialects.dialect import (
  8    arg_max_or_min_no_count,
  9    inline_array_sql,
 10    jarowinkler_similarity,
 11    json_extract_segments,
 12    json_path_key_only_name,
 13    length_or_char_length_sql,
 14    no_pivot_sql,
 15    rename_func,
 16    remove_from_array_using_filter,
 17    sha256_sql,
 18    strposition_sql,
 19    var_map_sql,
 20    unit_to_str,
 21    unit_to_var,
 22    trim_sql,
 23    sha2_digest_sql,
 24)
 25from sqlglot.generator import unsupported_args
 26from sqlglot.helper import is_int
 27from collections import defaultdict
 28
 29DATETIME_DELTA = t.Union[exp.DateAdd, exp.DateDiff, exp.DateSub, exp.TimestampSub, exp.TimestampAdd]
 30
 31
 32def _unix_to_time_sql(self: ClickHouseGenerator, expression: exp.UnixToTime) -> str:
 33    scale = expression.args.get("scale")
 34    timestamp = expression.this
 35
 36    if scale in (None, exp.UnixToTime.SECONDS):
 37        return self.func("fromUnixTimestamp", exp.cast(timestamp, exp.DType.BIGINT))
 38    if scale == exp.UnixToTime.MILLIS:
 39        return self.func("fromUnixTimestamp64Milli", exp.cast(timestamp, exp.DType.BIGINT))
 40    if scale == exp.UnixToTime.MICROS:
 41        return self.func("fromUnixTimestamp64Micro", exp.cast(timestamp, exp.DType.BIGINT))
 42    if scale == exp.UnixToTime.NANOS:
 43        return self.func("fromUnixTimestamp64Nano", exp.cast(timestamp, exp.DType.BIGINT))
 44
 45    return self.func(
 46        "fromUnixTimestamp",
 47        exp.cast(exp.Div(this=timestamp, expression=exp.func("POW", 10, scale)), exp.DType.BIGINT),
 48    )
 49
 50
 51def _lower_func(sql: str) -> str:
 52    index = sql.index("(")
 53    return sql[:index].lower() + sql[index:]
 54
 55
 56def _quantile_sql(self: ClickHouseGenerator, expression: exp.Quantile) -> str:
 57    quantile = expression.args["quantile"]
 58    args = f"({self.sql(expression, 'this')})"
 59
 60    if isinstance(quantile, exp.Array):
 61        func = self.func("quantiles", *quantile)
 62    else:
 63        func = self.func("quantile", quantile)
 64
 65    return func + args
 66
 67
 68def _datetime_delta_sql(name: str) -> t.Callable[[generator.Generator, DATETIME_DELTA], str]:
 69    def _delta_sql(self: generator.Generator, expression: DATETIME_DELTA) -> str:
 70        if not expression.unit:
 71            return rename_func(name)(self, expression)
 72
 73        return self.func(
 74            name,
 75            unit_to_var(expression),
 76            expression.expression,
 77            expression.this,
 78            expression.args.get("zone"),
 79        )
 80
 81    return _delta_sql
 82
 83
 84def _timestrtotime_sql(self: ClickHouseGenerator, expression: exp.TimeStrToTime):
 85    ts = expression.this
 86
 87    tz = expression.args.get("zone")
 88    if tz and isinstance(ts, exp.Literal):
 89        # Clickhouse will not accept timestamps that include a UTC offset, so we must remove them.
 90        # The first step to removing is parsing the string with `datetime.datetime.fromisoformat`.
 91        #
 92        # In python <3.11, `fromisoformat()` can only parse timestamps of millisecond (3 digit)
 93        # or microsecond (6 digit) precision. It will error if passed any other number of fractional
 94        # digits, so we extract the fractional seconds and pad to 6 digits before parsing.
 95        ts_string = ts.name.strip()
 96
 97        # separate [date and time] from [fractional seconds and UTC offset]
 98        ts_parts = ts_string.split(".")
 99        if len(ts_parts) == 2:
100            # separate fractional seconds and UTC offset
101            offset_sep = "+" if "+" in ts_parts[1] else "-"
102            ts_frac_parts = ts_parts[1].split(offset_sep)
103            num_frac_parts = len(ts_frac_parts)
104
105            # pad to 6 digits if fractional seconds present
106            ts_frac_parts[0] = ts_frac_parts[0].ljust(6, "0")
107            ts_string = "".join(
108                [
109                    ts_parts[0],  # date and time
110                    ".",
111                    ts_frac_parts[0],  # fractional seconds
112                    offset_sep if num_frac_parts > 1 else "",
113                    ts_frac_parts[1] if num_frac_parts > 1 else "",  # utc offset (if present)
114                ]
115            )
116
117        # return literal with no timezone, eg turn '2020-01-01 12:13:14-08:00' into '2020-01-01 12:13:14'
118        # this is because Clickhouse encodes the timezone as a data type parameter and throws an error if
119        # it's part of the timestamp string
120        ts_without_tz = (
121            datetime.datetime.fromisoformat(ts_string).replace(tzinfo=None).isoformat(sep=" ")
122        )
123        ts = exp.Literal.string(ts_without_tz)
124
125    # Non-nullable DateTime64 with microsecond precision
126    expressions = [exp.DataTypeParam(this=tz)] if tz else []
127    datatype = exp.DType.DATETIME64.into_expr(
128        expressions=[exp.DataTypeParam(this=exp.Literal.number(6)), *expressions],
129        nullable=False,
130    )
131
132    return self.sql(exp.cast(ts, datatype, dialect=self.dialect))
133
134
135def _map_sql(self: ClickHouseGenerator, expression: exp.Map | exp.VarMap) -> str:
136    if not (expression.parent and expression.parent.arg_key == "settings"):
137        return _lower_func(var_map_sql(self, expression))
138
139    keys = expression.args.get("keys")
140    values = expression.args.get("values")
141
142    if not isinstance(keys, exp.Array) or not isinstance(values, exp.Array):
143        self.unsupported("Cannot convert array columns into map.")
144        return ""
145
146    args = []
147    for key, value in zip(keys.expressions, values.expressions):
148        args.append(f"{self.sql(key)}: {self.sql(value)}")
149
150    csv_args = ", ".join(args)
151
152    return f"{{{csv_args}}}"
153
154
155def _json_cast_sql(self: ClickHouseGenerator, expression: exp.JSONCast) -> str:
156    this = self.sql(expression, "this")
157    to = expression.to
158    to_sql = self.sql(to)
159
160    if to.expressions:
161        to_sql = self.sql(exp.to_identifier(to_sql))
162
163    return f"{this}.:{to_sql}"
164
165
166class ClickHouseGenerator(generator.Generator):
167    SELECT_KINDS: tuple[str, ...] = ()
168    TRY_SUPPORTED = False
169    SUPPORTS_UESCAPE = False
170    SUPPORTS_DECODE_CASE = False
171
172    AFTER_HAVING_MODIFIER_TRANSFORMS = generator.AFTER_HAVING_MODIFIER_TRANSFORMS
173
174    QUERY_HINTS = False
175    STRUCT_DELIMITER = ("(", ")")
176    NVL2_SUPPORTED = False
177    TABLESAMPLE_REQUIRES_PARENS = False
178    TABLESAMPLE_SIZE_IS_ROWS = False
179    TABLESAMPLE_KEYWORDS = "SAMPLE"
180    LAST_DAY_SUPPORTS_DATE_PART = False
181    CAN_IMPLEMENT_ARRAY_ANY = True
182    SUPPORTS_TO_NUMBER = False
183    JOIN_HINTS = False
184    TABLE_HINTS = False
185    GROUPINGS_SEP = ""
186    SET_OP_MODIFIERS = False
187    ARRAY_SIZE_NAME = "LENGTH"
188    WRAP_DERIVED_VALUES = False
189
190    STRING_TYPE_MAPPING: t.ClassVar = {
191        exp.DType.BLOB: "String",
192        exp.DType.CHAR: "String",
193        exp.DType.LONGBLOB: "String",
194        exp.DType.LONGTEXT: "String",
195        exp.DType.MEDIUMBLOB: "String",
196        exp.DType.MEDIUMTEXT: "String",
197        exp.DType.TINYBLOB: "String",
198        exp.DType.TINYTEXT: "String",
199        exp.DType.TEXT: "String",
200        exp.DType.VARBINARY: "String",
201        exp.DType.VARCHAR: "String",
202    }
203
204    SUPPORTED_JSON_PATH_PARTS = {
205        exp.JSONPathKey,
206        exp.JSONPathRoot,
207        exp.JSONPathSubscript,
208    }
209
210    TYPE_MAPPING = {
211        **generator.Generator.TYPE_MAPPING,
212        exp.DType.BLOB: "String",
213        exp.DType.CHAR: "String",
214        exp.DType.LONGBLOB: "String",
215        exp.DType.LONGTEXT: "String",
216        exp.DType.MEDIUMBLOB: "String",
217        exp.DType.MEDIUMTEXT: "String",
218        exp.DType.TINYBLOB: "String",
219        exp.DType.TINYTEXT: "String",
220        exp.DType.TEXT: "String",
221        exp.DType.VARBINARY: "String",
222        exp.DType.VARCHAR: "String",
223        exp.DType.ARRAY: "Array",
224        exp.DType.BOOLEAN: "Bool",
225        exp.DType.BIGINT: "Int64",
226        exp.DType.DATE32: "Date32",
227        exp.DType.DATETIME: "DateTime",
228        exp.DType.DATETIME2: "DateTime",
229        exp.DType.SMALLDATETIME: "DateTime",
230        exp.DType.DATETIME64: "DateTime64",
231        exp.DType.DECIMAL: "Decimal",
232        exp.DType.DECIMAL32: "Decimal32",
233        exp.DType.DECIMAL64: "Decimal64",
234        exp.DType.DECIMAL128: "Decimal128",
235        exp.DType.DECIMAL256: "Decimal256",
236        exp.DType.TIMESTAMP: "DateTime",
237        exp.DType.TIMESTAMPNTZ: "DateTime",
238        exp.DType.TIMESTAMPTZ: "DateTime",
239        exp.DType.DOUBLE: "Float64",
240        exp.DType.ENUM: "Enum",
241        exp.DType.ENUM8: "Enum8",
242        exp.DType.ENUM16: "Enum16",
243        exp.DType.FIXEDSTRING: "FixedString",
244        exp.DType.FLOAT: "Float32",
245        exp.DType.INT: "Int32",
246        exp.DType.MEDIUMINT: "Int32",
247        exp.DType.INT128: "Int128",
248        exp.DType.INT256: "Int256",
249        exp.DType.LOWCARDINALITY: "LowCardinality",
250        exp.DType.MAP: "Map",
251        exp.DType.NESTED: "Nested",
252        exp.DType.NOTHING: "Nothing",
253        exp.DType.SMALLINT: "Int16",
254        exp.DType.STRUCT: "Tuple",
255        exp.DType.TINYINT: "Int8",
256        exp.DType.UBIGINT: "UInt64",
257        exp.DType.UINT: "UInt32",
258        exp.DType.UINT128: "UInt128",
259        exp.DType.UINT256: "UInt256",
260        exp.DType.USMALLINT: "UInt16",
261        exp.DType.UTINYINT: "UInt8",
262        exp.DType.IPV4: "IPv4",
263        exp.DType.IPV6: "IPv6",
264        exp.DType.POINT: "Point",
265        exp.DType.RING: "Ring",
266        exp.DType.LINESTRING: "LineString",
267        exp.DType.MULTILINESTRING: "MultiLineString",
268        exp.DType.POLYGON: "Polygon",
269        exp.DType.MULTIPOLYGON: "MultiPolygon",
270        exp.DType.AGGREGATEFUNCTION: "AggregateFunction",
271        exp.DType.SIMPLEAGGREGATEFUNCTION: "SimpleAggregateFunction",
272        exp.DType.DYNAMIC: "Dynamic",
273    }
274
275    TRANSFORMS = {
276        **generator.Generator.TRANSFORMS,
277        exp.AnyValue: rename_func("any"),
278        exp.ApproxDistinct: rename_func("uniq"),
279        exp.ArrayDistinct: rename_func("arrayDistinct"),
280        exp.ArrayConcat: rename_func("arrayConcat"),
281        exp.ArrayContains: rename_func("has"),
282        exp.ArrayFilter: lambda self, e: self.func("arrayFilter", e.expression, e.this),
283        exp.Transform: lambda self, e: self.func("arrayMap", e.expression, e.this),
284        exp.ArrayRemove: remove_from_array_using_filter,
285        exp.ArrayReverse: rename_func("arrayReverse"),
286        exp.ArraySlice: rename_func("arraySlice"),
287        exp.ArraySum: rename_func("arraySum"),
288        exp.ArrayMax: rename_func("arrayMax"),
289        exp.ArrayMin: rename_func("arrayMin"),
290        exp.ArgMax: arg_max_or_min_no_count("argMax"),
291        exp.ArgMin: arg_max_or_min_no_count("argMin"),
292        exp.Array: inline_array_sql,
293        exp.CityHash64: rename_func("cityHash64"),
294        exp.CastToStrType: rename_func("CAST"),
295        exp.CurrentDatabase: rename_func("CURRENT_DATABASE"),
296        exp.CurrentSchemas: rename_func("CURRENT_SCHEMAS"),
297        exp.CountIf: rename_func("countIf"),
298        exp.CosineDistance: rename_func("cosineDistance"),
299        exp.CompressColumnConstraint: lambda self, e: (
300            f"CODEC({self.expressions(e, key='this', flat=True)})"
301        ),
302        exp.ComputedColumnConstraint: lambda self, e: (
303            f"{'MATERIALIZED' if e.args.get('persisted') else 'ALIAS'} {self.sql(e, 'this')}"
304        ),
305        exp.CurrentDate: lambda self, e: self.func("CURRENT_DATE"),
306        exp.CurrentVersion: rename_func("VERSION"),
307        exp.DateAdd: _datetime_delta_sql("DATE_ADD"),
308        exp.DateDiff: _datetime_delta_sql("DATE_DIFF"),
309        exp.DateStrToDate: rename_func("toDate"),
310        exp.DateSub: _datetime_delta_sql("DATE_SUB"),
311        exp.Explode: rename_func("arrayJoin"),
312        exp.FarmFingerprint: rename_func("farmFingerprint64"),
313        exp.Final: lambda self, e: f"{self.sql(e, 'this')} FINAL",
314        exp.IsNan: rename_func("isNaN"),
315        exp.JarowinklerSimilarity: jarowinkler_similarity("jaroWinklerSimilarity"),
316        exp.JSONCast: _json_cast_sql,
317        exp.JSONExtract: json_extract_segments("JSONExtractString", quoted_index=False),
318        exp.JSONExtractScalar: json_extract_segments("JSONExtractString", quoted_index=False),
319        exp.JSONPathKey: json_path_key_only_name,
320        exp.JSONPathRoot: lambda *_: "",
321        exp.Length: length_or_char_length_sql,
322        exp.Map: _map_sql,
323        exp.Median: rename_func("median"),
324        exp.Nullif: rename_func("nullIf"),
325        exp.PartitionedByProperty: lambda self, e: f"PARTITION BY {self.sql(e, 'this')}",
326        exp.Pivot: no_pivot_sql,
327        exp.Quantile: _quantile_sql,
328        exp.RegexpLike: lambda self, e: self.func("match", e.this, e.expression),
329        exp.Rand: rename_func("randCanonical"),
330        exp.StartsWith: rename_func("startsWith"),
331        exp.Struct: rename_func("tuple"),
332        exp.Trunc: rename_func("trunc"),
333        exp.EndsWith: rename_func("endsWith"),
334        exp.EuclideanDistance: rename_func("L2Distance"),
335        exp.StrPosition: lambda self, e: strposition_sql(
336            self,
337            e,
338            func_name="POSITION",
339            supports_position=True,
340            use_ansi_position=False,
341        ),
342        exp.TimeToStr: lambda self, e: self.func(
343            "formatDateTime",
344            e.this.this if isinstance(e.this, exp.TsOrDsToTimestamp) else e.this,
345            self.format_time(e),
346            e.args.get("zone"),
347        ),
348        exp.TimeStrToTime: _timestrtotime_sql,
349        exp.TimestampAdd: _datetime_delta_sql("TIMESTAMP_ADD"),
350        exp.TimestampSub: _datetime_delta_sql("TIMESTAMP_SUB"),
351        exp.Typeof: rename_func("toTypeName"),
352        exp.VarMap: _map_sql,
353        exp.Xor: lambda self, e: self.func("xor", e.this, e.expression),
354        exp.MD5Digest: rename_func("MD5"),
355        exp.MD5: lambda self, e: self.func("LOWER", self.func("HEX", self.func("MD5", e.this))),
356        exp.SHA: rename_func("SHA1"),
357        exp.SHA1Digest: rename_func("SHA1"),
358        exp.SHA2: sha256_sql,
359        exp.SHA2Digest: sha2_digest_sql,
360        exp.Split: lambda self, e: self.func(
361            "splitByString", e.args.get("expression"), e.this, e.args.get("limit")
362        ),
363        exp.RegexpSplit: lambda self, e: self.func(
364            "splitByRegexp", e.args.get("expression"), e.this, e.args.get("limit")
365        ),
366        exp.UnixToTime: _unix_to_time_sql,
367        exp.Trim: lambda self, e: trim_sql(self, e, default_trim_type="BOTH"),
368        exp.Variance: rename_func("varSamp"),
369        exp.SchemaCommentProperty: lambda self, e: self.naked_property(e),
370        exp.Stddev: rename_func("stddevSamp"),
371        exp.Chr: rename_func("CHAR"),
372        exp.Lag: lambda self, e: self.func(
373            "lagInFrame", e.this, e.args.get("offset"), e.args.get("default")
374        ),
375        exp.Lead: lambda self, e: self.func(
376            "leadInFrame", e.this, e.args.get("offset"), e.args.get("default")
377        ),
378        exp.Levenshtein: unsupported_args("ins_cost", "del_cost", "sub_cost", "max_dist")(
379            rename_func("editDistance")
380        ),
381        exp.ParseDatetime: lambda self, e: self.func(
382            "parseDateTime", e.this, e.args.get("format"), e.args.get("zone")
383        ),
384    }
385
386    PROPERTIES_LOCATION = {
387        **generator.Generator.PROPERTIES_LOCATION,
388        exp.DefinerProperty: exp.Properties.Location.POST_SCHEMA,
389        exp.OnCluster: exp.Properties.Location.POST_NAME,
390        exp.PartitionedByProperty: exp.Properties.Location.POST_SCHEMA,
391        exp.ToTableProperty: exp.Properties.Location.POST_NAME,
392        exp.UuidProperty: exp.Properties.Location.POST_NAME,
393        exp.VolatileProperty: exp.Properties.Location.UNSUPPORTED,
394    }
395
396    # There's no list in docs, but it can be found in Clickhouse code
397    # see `ClickHouse/src/Parsers/ParserCreate*.cpp`
398    ON_CLUSTER_TARGETS = {
399        "SCHEMA",  # Transpiled CREATE SCHEMA may have OnCluster property set
400        "DATABASE",
401        "TABLE",
402        "VIEW",
403        "DICTIONARY",
404        "INDEX",
405        "FUNCTION",
406        "NAMED COLLECTION",
407    }
408
409    # https://clickhouse.com/docs/en/sql-reference/data-types/nullable
410    NON_NULLABLE_TYPES = {
411        exp.DType.ARRAY,
412        exp.DType.MAP,
413        exp.DType.STRUCT,
414        exp.DType.POINT,
415        exp.DType.RING,
416        exp.DType.LINESTRING,
417        exp.DType.MULTILINESTRING,
418        exp.DType.POLYGON,
419        exp.DType.MULTIPOLYGON,
420    }
421
422    def groupconcat_sql(self, expression: exp.GroupConcat) -> str:
423        this = expression.this
424        separator = expression.args.get("separator")
425
426        if isinstance(this, exp.Limit) and this.this:
427            limit = this
428            this = limit.this.pop()
429            return self.sql(
430                exp.ParameterizedAgg(
431                    this="groupConcat",
432                    params=[this],
433                    expressions=[separator, limit.expression],
434                )
435            )
436
437        if separator:
438            return self.sql(
439                exp.ParameterizedAgg(
440                    this="groupConcat",
441                    params=[this],
442                    expressions=[separator],
443                )
444            )
445
446        return self.func("groupConcat", this)
447
448    def offset_sql(self, expression: exp.Offset) -> str:
449        offset = super().offset_sql(expression)
450
451        # OFFSET ... FETCH syntax requires a "ROW" or "ROWS" keyword
452        # https://clickhouse.com/docs/sql-reference/statements/select/offset
453        parent = expression.parent
454        if isinstance(parent, exp.Select) and isinstance(parent.args.get("limit"), exp.Fetch):
455            offset = f"{offset} ROWS"
456
457        return offset
458
459    def strtodate_sql(self, expression: exp.StrToDate) -> str:
460        strtodate_sql = self.function_fallback_sql(expression)
461
462        if not isinstance(expression.parent, exp.Cast):
463            # StrToDate returns DATEs in other dialects (eg. postgres), so
464            # this branch aims to improve the transpilation to clickhouse
465            return self.cast_sql(exp.cast(expression, "DATE"))
466
467        return strtodate_sql
468
469    def cast_sql(self, expression: exp.Cast, safe_prefix: str | None = None) -> str:
470        this = expression.this
471
472        if isinstance(this, exp.StrToDate) and expression.to == exp.DType.DATETIME.into_expr():
473            return self.sql(this)
474
475        return super().cast_sql(expression, safe_prefix=safe_prefix)
476
477    def trycast_sql(self, expression: exp.TryCast) -> str:
478        dtype = expression.to
479        if not dtype.is_type(*self.NON_NULLABLE_TYPES, check_nullable=True):
480            # Casting x into Nullable(T) appears to behave similarly to TRY_CAST(x AS T)
481            dtype.set("nullable", True)
482
483        return super().cast_sql(expression)
484
485    def _jsonpathsubscript_sql(self, expression: exp.JSONPathSubscript) -> str:
486        this = self.json_path_part(expression.this)
487        return str(int(this) + 1) if is_int(this) else this
488
489    def likeproperty_sql(self, expression: exp.LikeProperty) -> str:
490        return f"AS {self.sql(expression, 'this')}"
491
492    def _any_to_has(
493        self,
494        expression: exp.EQ | exp.NEQ,
495        default: t.Callable[[t.Any], str],
496        prefix: str = "",
497    ) -> str:
498        if isinstance(expression.left, exp.Any):
499            arr = expression.left
500            this = expression.right
501        elif isinstance(expression.right, exp.Any):
502            arr = expression.right
503            this = expression.left
504        else:
505            return default(expression)
506
507        return prefix + self.func("has", arr.this.unnest(), this)
508
509    def eq_sql(self, expression: exp.EQ) -> str:
510        return self._any_to_has(expression, super().eq_sql)
511
512    def neq_sql(self, expression: exp.NEQ) -> str:
513        return self._any_to_has(expression, super().neq_sql, "NOT ")
514
515    def regexpilike_sql(self, expression: exp.RegexpILike) -> str:
516        # Manually add a flag to make the search case-insensitive
517        regex = self.func("CONCAT", "'(?i)'", expression.expression)
518        return self.func("match", expression.this, regex)
519
520    def datatype_sql(self, expression: exp.DataType) -> str:
521        # String is the standard ClickHouse type, every other variant is just an alias.
522        # Additionally, any supplied length parameter will be ignored.
523        #
524        # https://clickhouse.com/docs/en/sql-reference/data-types/string
525        if expression.this in self.STRING_TYPE_MAPPING:
526            dtype = "String"
527        else:
528            dtype = super().datatype_sql(expression)
529
530        # This section changes the type to `Nullable(...)` if the following conditions hold:
531        # - It's marked as nullable - this ensures we won't wrap ClickHouse types with `Nullable`
532        #   and change their semantics
533        # - It's not the key type of a `Map`. This is because ClickHouse enforces the following
534        #   constraint: "Type of Map key must be a type, that can be represented by integer or
535        #   String or FixedString (possibly LowCardinality) or UUID or IPv6"
536        # - It's not a composite type, e.g. `Nullable(Array(...))` is not a valid type
537        parent = expression.parent
538        nullable = expression.args.get("nullable")
539        if nullable is True or (
540            nullable is None
541            and not (
542                isinstance(parent, exp.DataType)
543                and parent.is_type(exp.DType.MAP, check_nullable=True)
544                and expression.index in (None, 0)
545            )
546            and not expression.is_type(*self.NON_NULLABLE_TYPES, check_nullable=True)
547        ):
548            dtype = f"Nullable({dtype})"
549
550        return dtype
551
552    def cte_sql(self, expression: exp.CTE) -> str:
553        if expression.args.get("scalar"):
554            this = self.sql(expression, "this")
555            alias = self.sql(expression, "alias")
556            return f"{this} AS {alias}"
557
558        return super().cte_sql(expression)
559
560    def after_limit_modifiers(self, expression: exp.Expr) -> list[str]:
561        return super().after_limit_modifiers(expression) + [
562            (
563                self.seg("SETTINGS ") + self.expressions(expression, key="settings", flat=True)
564                if expression.args.get("settings")
565                else ""
566            ),
567            (
568                self.seg("FORMAT ") + self.sql(expression, "format")
569                if expression.args.get("format")
570                else ""
571            ),
572        ]
573
574    def placeholder_sql(self, expression: exp.Placeholder) -> str:
575        return f"{{{expression.name}: {self.sql(expression, 'kind')}}}"
576
577    def oncluster_sql(self, expression: exp.OnCluster) -> str:
578        return f"ON CLUSTER {self.sql(expression, 'this')}"
579
580    def createable_sql(self, expression: exp.Create, locations: defaultdict) -> str:
581        if expression.kind in self.ON_CLUSTER_TARGETS and locations.get(
582            exp.Properties.Location.POST_NAME
583        ):
584            this_name = self.sql(
585                expression.this if isinstance(expression.this, exp.Schema) else expression,
586                "this",
587            )
588            this_properties = " ".join(
589                [self.sql(prop) for prop in locations[exp.Properties.Location.POST_NAME]]
590            )
591            this_schema = self.schema_columns_sql(expression.this)
592            this_schema = f"{self.sep()}{this_schema}" if this_schema else ""
593
594            return f"{this_name}{self.sep()}{this_properties}{this_schema}"
595
596        return super().createable_sql(expression, locations)
597
598    def create_sql(self, expression: exp.Create) -> str:
599        # The comment property comes last in CTAS statements, i.e. after the query
600        query = expression.expression
601        if isinstance(query, exp.Query):
602            comment_prop = expression.find(exp.SchemaCommentProperty)
603            if comment_prop:
604                comment_prop.pop()
605                query.replace(exp.paren(query))
606        else:
607            comment_prop = None
608
609        create_sql = super().create_sql(expression)
610
611        comment_sql = self.sql(comment_prop)
612        comment_sql = f" {comment_sql}" if comment_sql else ""
613
614        return f"{create_sql}{comment_sql}"
615
616    def prewhere_sql(self, expression: exp.PreWhere) -> str:
617        this = self.indent(self.sql(expression, "this"))
618        return f"{self.seg('PREWHERE')}{self.sep()}{this}"
619
620    def indexcolumnconstraint_sql(self, expression: exp.IndexColumnConstraint) -> str:
621        this = self.sql(expression, "this")
622        this = f" {this}" if this else ""
623        expr = self.sql(expression, "expression")
624        expr = f" {expr}" if expr else ""
625        index_type = self.sql(expression, "index_type")
626        index_type = f" TYPE {index_type}" if index_type else ""
627        granularity = self.sql(expression, "granularity")
628        granularity = f" GRANULARITY {granularity}" if granularity else ""
629
630        return f"INDEX{this}{expr}{index_type}{granularity}"
631
632    def partition_sql(self, expression: exp.Partition) -> str:
633        return f"PARTITION {self.expressions(expression, flat=True)}"
634
635    def partitionid_sql(self, expression: exp.PartitionId) -> str:
636        return f"ID {self.sql(expression.this)}"
637
638    def replacepartition_sql(self, expression: exp.ReplacePartition) -> str:
639        return f"REPLACE {self.sql(expression.expression)} FROM {self.sql(expression, 'source')}"
640
641    def projectiondef_sql(self, expression: exp.ProjectionDef) -> str:
642        return f"PROJECTION {self.sql(expression.this)} {self.wrap(expression.expression)}"
643
644    def nestedjsonselect_sql(self, expression: exp.NestedJSONSelect) -> str:
645        return f"{self.sql(expression, 'this')}.^{self.sql(expression, 'expression')}"
646
647    def is_sql(self, expression: exp.Is) -> str:
648        is_sql = super().is_sql(expression)
649
650        if isinstance(expression.parent, exp.Not):
651            # value IS NOT NULL -> NOT (value IS NULL)
652            is_sql = self.wrap(is_sql)
653
654        return is_sql
655
656    def in_sql(self, expression: exp.In) -> str:
657        in_sql = super().in_sql(expression)
658
659        if isinstance(expression.parent, exp.Not) and expression.args.get("is_global"):
660            in_sql = in_sql.replace("GLOBAL IN", "GLOBAL NOT IN", 1)
661
662        return in_sql
663
664    def not_sql(self, expression: exp.Not) -> str:
665        if isinstance(expression.this, exp.In):
666            if expression.this.args.get("is_global"):
667                # let `GLOBAL IN` child interpose `NOT`
668                return self.sql(expression, "this")
669
670            expression.set("this", exp.paren(expression.this, copy=False))
671
672        return super().not_sql(expression)
673
674    def values_sql(self, expression: exp.Values, values_as_table: bool = True) -> str:
675        # If the VALUES clause contains tuples of expressions, we need to treat it
676        # as a table since Clickhouse will automatically alias it as such.
677        alias = expression.args.get("alias")
678
679        if alias and alias.args.get("columns") and expression.expressions:
680            values = expression.expressions[0].expressions
681            values_as_table = any(isinstance(value, exp.Tuple) for value in values)
682        else:
683            values_as_table = True
684
685        return super().values_sql(expression, values_as_table=values_as_table)
686
687    def timestamptrunc_sql(self, expression: exp.DateTrunc | exp.TimestampTrunc) -> str:
688        unit = unit_to_str(expression)
689        # https://clickhouse.com/docs/whats-new/changelog/2023#improvement
690        if self.dialect.version < (23, 12) and unit and unit.is_string:
691            unit = exp.Literal.string(unit.name.lower())
692        return self.func("dateTrunc", unit, expression.this, expression.args.get("zone"))
693
694    def datetrunc_sql(self, expression: exp.DateTrunc) -> str:
695        return self.timestamptrunc_sql(expression)