add upsert information

doc/sphinx/dev_guide/box-protocol.rst

@@ -109,6 +109,7 @@ Let's list them here too:
     <function_name> ::= 0x22
     <username>      ::= 0x23
     <expression>    ::= 0x27
+    <def_tuple>     ::= 0x28
     <data>          ::= 0x30
     <error>         ::= 0x31
 
@@ -124,6 +125,7 @@ Let's list them here too:
     <call>    ::= 0x06
     <auth>    ::= 0x07
     <eval>    ::= 0x08
+    <upsert>  ::= 0x09
     -- Admin command codes
     <ping>    ::= 0x40
 
@@ -378,6 +380,48 @@ It's an error to specify an argument of a type that differs from expected type.
                         MP_MAP
 
 
+* UPSERT: CODE - 0x09
+  Update tuple if it would be found elsewhere try to insert tuple. Always use primary index for key.
+
+  
+  
+.. code-block:: bash
+
+    UPSERT BODY:
+    
+    +==================+==========================+
+    |                  |                          |
+    |   0x10: SPACE_ID |   0x20: KEY              |
+    | MP_INT: MP_INT   | MP_INT: MP_ARRAY         |
+    |                  |                          |
+    +==================+==========================+
+    |                  |             +~~~~~~~~~~+ |
+    |                  |             |          | |
+    |                  | (DEF_TUPLE) |    OP    | |
+    |   0x21: TUPLE    |       0x28: |          | |
+    | MP_INT: MP_ARRAY |     MP_INT: +~~~~~~~~~~+ |
+    |                  |               MP_ARRAY   |
+    +==================+==========================+
+                    MP_MAP
+  
+    Operations structure same as for UPDATE operation.
+       0           2
+    +-----------+==========+==========+
+    |           |          |          |
+    |    OP     | FIELD_NO | ARGUMENT |
+    | MP_FIXSTR |  MP_INT  |  MP_INT  |
+    |           |          |          |
+    +-----------+==========+==========+
+                  MP_ARRAY
+    
+    Support operations: 
+    '+' - add a value to a numeric field. If the filed is not numeric, it's changed to 0 first. If the field does not exist, the operation is skipped. There is no error in case of overflow either, the value simply wraps around in C style. The range of the integer is MsgPack: from -2^63 to 2^64-1
+    '-' - same as the previous, but subtract a value
+    '=' - assign a field to a value. The field must exist, if it does not exist, the operation is skipped.
+    '!' - insert a field. It's only possible to insert a field if this create no nil "gaps" between fields. E.g. it's possible to add a field between existing fields or as the last field of the tuple.
+    '#' - delete a field. If the field does not exist, the operation is skipped. It's not possible to change with update operations a part of the primary key (this is validated before performing upsert).
+
+
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                          Response packet structure
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