If you set the compression option to zlib, you can use this option to specify the compression window size for download.

Syntax

zlib_download_window_size=window-bits

Protocols

• TCPIP, TLS, HTTP, HTTPS

Support notes

• Cannot be used in the ML directive of the Redirector.
• Not supported on Palm OS or Symbian.

Default

12 on Windows Mobile, otherwise 15

Remarks

To turn off compression for downloads, set window-bits to 0. Otherwise, the window size can be a value between 9 and 15 inclusive. In general, better compression rates can be achieved with a higher window size, but more memory is required.

window-bits is the base two logarithm of the window size (the size of the history buffer). The following formulas can be used to determine how much memory is used on the client for each window-bits:

upload (compress): memory = 2(window-bits + 3)

download (decompress): memory = 2(window-bits)

To support zlib compression in UltraLite, an application must call ULEnableZlibSyncCompression( sqlca ) and mlczlib10.dll must be deployed.

For information about how to set network protocol options with dbmlsync, see CommunicationAddress (adr) extended option.

For information about how to set network protocol options with UltraLite, see Network protocol options for UltraLite synchronization streams.

See also

• compression
• zlib_upload_window_size

Example

The following option sets compression for upload only:

"compression=zlib;zlib_download_window_size=0"