Data Formats

When it comes to data formats, chDB is 100% feature compatible with ClickHouse.

Input formats are used to parse the data provided to INSERT and SELECT from a file-backed table such as File, URL or S3. Output formats are used to arrange the results of a SELECT, and to perform INSERTs into a file-backed table. As well as the data formats that ClickHouse supports, chDB also supports:

• ArrowTable as an output format, the type is Python pyarrow.Table

• DataFrame as an input and output format, the type is Python pandas.DataFrame. For examples, see test_joindf.py

• Debug as ab output (as an alias of CSV), but with enabled debug verbose output from ClickHouse.

  The supported data formats from ClickHouse are:

  Format	Input	Output
  TabSeparated	✔	✔
  TabSeparatedRaw	✔	✔
  TabSeparatedWithNames	✔	✔
  TabSeparatedWithNamesAndTypes	✔	✔
  TabSeparatedRawWithNames	✔	✔
  TabSeparatedRawWithNamesAndTypes	✔	✔
  Template	✔	✔
  TemplateIgnoreSpaces	✔	✗
  CSV	✔	✔
  CSVWithNames	✔	✔
  CSVWithNamesAndTypes	✔	✔
  CustomSeparated	✔	✔
  CustomSeparatedWithNames	✔	✔
  CustomSeparatedWithNamesAndTypes	✔	✔
  SQLInsert	✗	✔
  Values	✔	✔
  Vertical	✗	✔
  JSON	✔	✔
  JSONAsString	✔	✗
  JSONStrings	✔	✔
  JSONColumns	✔	✔
  JSONColumnsWithMetadata	✔	✔
  JSONCompact	✔	✔
  JSONCompactStrings	✗	✔
  JSONCompactColumns	✔	✔
  JSONEachRow	✔	✔
  PrettyJSONEachRow	✗	✔
  JSONEachRowWithProgress	✗	✔
  JSONStringsEachRow	✔	✔
  JSONStringsEachRowWithProgress	✗	✔
  JSONCompactEachRow	✔	✔
  JSONCompactEachRowWithNames	✔	✔
  JSONCompactEachRowWithNamesAndTypes	✔	✔
  JSONCompactStringsEachRow	✔	✔
  JSONCompactStringsEachRowWithNames	✔	✔
  JSONCompactStringsEachRowWithNamesAndTypes	✔	✔
  JSONObjectEachRow	✔	✔
  BSONEachRow	✔	✔
  TSKV	✔	✔
  Pretty	✗	✔
  PrettyNoEscapes	✗	✔
  PrettyMonoBlock	✗	✔
  PrettyNoEscapesMonoBlock	✗	✔
  PrettyCompact	✗	✔
  PrettyCompactNoEscapes	✗	✔
  PrettyCompactMonoBlock	✗	✔
  PrettyCompactNoEscapesMonoBlock	✗	✔
  PrettySpace	✗	✔
  PrettySpaceNoEscapes	✗	✔
  PrettySpaceMonoBlock	✗	✔
  PrettySpaceNoEscapesMonoBlock	✗	✔
  Prometheus	✗	✔
  Protobuf	✔	✔
  ProtobufSingle	✔	✔
  Avro	✔	✔
  AvroConfluent	✔	✗
  Parquet	✔	✔
  ParquetMetadata	✔	✗
  Arrow	✔	✔
  ArrowStream	✔	✔
  ORC	✔	✔
  One	✔	✗
  RowBinary	✔	✔
  RowBinaryWithNames	✔	✔
  RowBinaryWithNamesAndTypes	✔	✔
  RowBinaryWithDefaults	✔	✔
  Native	✔	✔
  Null	✗	✔
  XML	✗	✔
  CapnProto	✔	✔
  LineAsString	✔	✔
  Regexp	✔	✗
  RawBLOB	✔	✔
  MsgPack	✔	✔
  MySQLDump	✔	✗
  Markdown	✗	✔

  For further information and examples, see ClickHouse formats for input and output data.