Support of ZLIB and GZIP Formats

Compression and Decompression of ZLIB Stream

In order to be compatible with ZLIB compression or decompression, Intel® Query Processing Library (Intel® QPL) needs to either wrap the output stream (on a first and last job, when doing compression) and insert the correct ZLIB header and trailer information, or unwrap (on a first job, when doing decompression) the provided stream.

By default, Intel QPL generates a raw Deflate stream, so in order to add or remove ZLIB header and trailer information, the flag QPL_FLAG_ZLIB_MODE must be specified. Refer to RFC 1950 for more details on ZLIB header and trailer.

Warning

Intel QPL supports only 4 KB Window size for both software_path and hardware_path execution. If the stream was compressed with a larger Window size, an error is returned.

Compression and Decompression of GZIP Stream

Similarly, the GZIP standard defines an encapsulation layer (consisting of a header and trailer) around a Deflate stream. If the QPL_FLAG_GZIP_MODE flag is specified, the library will add GZIP header and trailer information to the output stream (when performing compression) or skip over the GZIP header on the first job and then start parsing the Deflate stream (when performing decompression). Refer to RFC 1952 for more details on GZIP header and trailer.