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Doc: Update compression protocol information #502

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13 changes: 10 additions & 3 deletions sql-common/net_serv.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1055,6 +1055,9 @@ static bool net_write_raw_loop(NET *net, const uchar *buf, size_t count) {
- Server finishes the @ref page_protocol_connection_phase with an
@ref page_protocol_basic_ok_packet.

If both ::CLIENT_COMPRESS and ::CLIENT_ZSTD_COMPRESSION_ALGORITHM are set
then zlib is used.

@subpage page_protocol_basic_compression_packet
*/

Expand All @@ -1079,6 +1082,9 @@ static bool net_write_raw_loop(NET *net, const uchar *buf, size_t count) {
<td>compressed sequence id</td>
<td>Sequence ID of the compressed packets, reset in the same way as the
@ref sect_protocol_basic_packets_packet, but incremented independently</td></tr>
<tr><td>@ref a_protocol_type_int3 "int&lt;3&gt;"</td>
<td>length of uncompressed payload</td>
<td>Length of payload before compression</td></tr>
</table>

@section sect_protocol_basic_compression_packet_compressed_payload Compressed Payload
Expand All @@ -1087,10 +1093,11 @@ static bool net_write_raw_loop(NET *net, const uchar *buf, size_t count) {
@ref sect_protocol_basic_compression_packet_header is followed by the
compressed payload.

It uses the *deflate* algorithm as described in
Depending on which capability flags are set it uses the *deflate* algorithm as described in
[RFC 1951](http://tools.ietf.org/html/rfc1951.html) and implemented in
[zlib](http://zlib.org/). The header of the compressed packet has the
parameters of the `uncompress()` function in mind:
[zlib](http://zlib.org/) or [Zstandard](https://facebook.github.io/zstd/).

When using zlib, the header of the compressed packet has the parameters of the `uncompress()` function in mind:

~~~~~~~~~~~~~
ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
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