{"record":{"id":"72302c8045185b25","repo":"pathwaycom/pathway","slug":"failed-to-detect-the-region-of-s3-bucket-bucket-r","errorCode":null,"errorMessage":"Failed to detect the region of S3 bucket {bucket!r} (HTTP status {response.status_code}): the bucket may not exist. If it does, pass AwsS3Settings with an explicit region","messagePattern":"Failed to detect the region of S3 bucket (.+?) \\(HTTP status (.+?)\\): the bucket may not exist\\. If it does, pass AwsS3Settings with an explicit region","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"python/pathway/internals/_io_helpers.py","lineNumber":166,"sourceCode":"            has_extra_chars = len(s3_path) > len(s3_path_prefix)\n            if not starts_with_prefix or not has_extra_chars:\n                continue\n            bucket = s3_path[len(s3_path_prefix) :].split(\"/\")[0]\n\n            # the crate we use on the Rust-engine side can't detect the location of a\n            # bucket, so it's done here; S3 reports the region of a bucket in a response\n            # header, even for anonymous requests and even when it replies with a\n            # redirect or an access denial\n            import requests\n\n            response = requests.head(\n                f\"https://s3.amazonaws.com/{bucket}\",\n                allow_redirects=False,\n                timeout=S3_REGION_DETECTION_TIMEOUT_S,\n            )\n            region = response.headers.get(\"x-amz-bucket-region\")\n            if region is None:\n                raise ValueError(\n                    f\"Failed to detect the region of S3 bucket {bucket!r} \"\n                    f\"(HTTP status {response.status_code}): the bucket may not exist. \"\n                    \"If it does, pass AwsS3Settings with an explicit region\"\n                )\n\n            return cls(\n                bucket_name=bucket,\n                region=region,\n            )\n\n        # If it doesn't start with a valid S3 prefix, it's not a full S3 path\n        raise ValueError(f\"Incorrect S3 path: {s3_path}\")\n\n    def authorize(self):\n        \"\"\"Fills in the credentials that the downstream libraries can't deduce.\n\n        The DeltaLake library resolves environment variables and instance\n        credentials on its own, but does not read AWS profile files — those are","sourceCodeStart":148,"sourceCodeEnd":184,"githubUrl":"https://github.com/pathwaycom/pathway/blob/fa2f74a4649b7c5908690cf60137263d8d80de5f/python/pathway/internals/_io_helpers.py#L148-L184","documentation":"pw.io.clickhouse.write appends system metadata columns to every output row: {time, diff} in the default streaming mode, or {version, is_deleted} when output_table_type=\"snapshot\". If the user's schema already contains columns with those names, the write would be ambiguous, so it is rejected up front.","triggerScenarios":"Calling pw.io.clickhouse.write with a table whose schema includes a column named time or diff (default mode), or version / is_deleted (snapshot mode).","commonSituations":"CDC-style or audit schemas that naturally carry time/diff/version columns; switching output_table_type between runs changes which pair is reserved, so a schema that worked in one mode fails in the other.","solutions":["Rename the colliding column(s) in the Pathway schema before writing (e.g. time -> event_time, diff -> change_diff).","If you must keep names in ClickHouse, rename in Pathway and map back with a ClickHouse VIEW or column alias downstream.","Check which pair applies to your output_table_type and only rename those names."],"exampleFix":"# before\nclass Input(pw.Schema):\n    time: int\n    value: str\npw.io.clickhouse.write(t, \"db.table\")\n\n# after\nt = t.with_columns(event_time=t.time).without(pw.this.time)\npw.io.clickhouse.write(t, \"db.table\")","handlingStrategy":"validation","validationCode":"def check_clickhouse_names(table: pw.Table, output_table_type: str) -> None:\n    reserved = {\"version\", \"is_deleted\"} if output_table_type == \"snapshot\" else {\"time\", \"diff\"}\n    clash = reserved & set(table.schema.column_names())\n    if clash:\n        raise ValueError(f\"rename columns {sorted(clash)}; they are reserved\")\n\ncheck_clickhouse_names(t, output_table_type)\npw.io.clickhouse.write(t, ..., output_table_type=output_table_type)","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Avoid naming Pathway schema columns time/diff/version/is_deleted when targeting ClickHouse.","Re-check reserved names whenever output_table_type changes between modes."],"tags":["pathway","clickhouse","schema","reserved-names","validation"],"backgroundTag":null,"analyzedSha":"fa2f74a4649b7c5908690cf60137263d8d80de5f","analyzedAt":"2026-08-15T01:48:17.006Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}