{
    "XADD": {
        "summary": "Appends a new message to a stream. Creates the key if it doesn't exist.",
        "complexity": "O(1) when adding a new entry, O(N) when trimming where N being the number of entries evicted.",
        "group": "stream",
        "since": "5.0.0",
        "arity": -5,
        "function": "xaddCommand",
        "history": [
            [
                "6.2.0",
                "Added the `NOMKSTREAM` option, `MINID` trimming strategy and the `LIMIT` option."
            ],
            [
                "7.0.0",
                "Added support for the `<ms>-*` explicit ID form."
            ]
        ],
        "command_flags": [
            "WRITE",
            "DENYOOM",
            "FAST"
        ],
        "acl_categories": [
            "STREAM"
        ],
        "command_tips": [
            "NONDETERMINISTIC_OUTPUT"
        ],
        "key_specs": [
            {
                "notes": "UPDATE instead of INSERT because of the optional trimming feature",
                "flags": [
                    "RW",
                    "UPDATE"
                ],
                "begin_search": {
                    "index": {
                        "pos": 1
                    }
                },
                "find_keys": {
                    "range": {
                        "lastkey": 0,
                        "step": 1,
                        "limit": 0
                    }
                }
            }
        ],
        "arguments": [
            {
                "name": "key",
                "type": "key",
                "key_spec_index": 0
            },
            {
                "token": "NOMKSTREAM",
                "name": "nomkstream",
                "type": "pure-token",
                "optional": true,
                "since": "6.2.0"
            },
            {
                "name": "trim",
                "type": "block",
                "optional": true,
                "arguments": [
                    {
                        "name": "strategy",
                        "type": "oneof",
                        "arguments": [
                            {
                                "name": "maxlen",
                                "type": "pure-token",
                                "token": "MAXLEN"
                            },
                            {
                                "name": "minid",
                                "type": "pure-token",
                                "token": "MINID",
                                "since": "6.2.0"
                            }
                        ]
                    },
                    {
                        "name": "operator",
                        "type": "oneof",
                        "optional": true,
                        "arguments": [
                            {
                                "name": "equal",
                                "type": "pure-token",
                                "token": "="
                            },
                            {
                                "name": "approximately",
                                "type": "pure-token",
                                "token": "~"
                            }
                        ]
                    },
                    {
                        "name": "threshold",
                        "type": "string"
                    },
                    {
                        "token": "LIMIT",
                        "name": "count",
                        "type": "integer",
                        "optional": true,
                        "since": "6.2.0"
                    }
                ]
            },
            {
                "name": "id-selector",
                "type": "oneof",
                "arguments": [
                    {
                        "name": "auto-id",
                        "type": "pure-token",
                        "token": "*"
                    },
                    {
                        "name": "id",
                        "type": "string"
                    }
                ]
            },
            {
                "name": "data",
                "type": "block",
                "multiple": true,
                "arguments": [
                    {
                        "name": "field",
                        "type": "string"
                    },
                    {
                        "name": "value",
                        "type": "string"
                    }
                ]
            }
        ],
        "reply_schema": {
            "oneOf":[
                {
                    "description": "The ID of the added entry. The ID is the one auto-generated if * is passed as ID argument, otherwise the command just returns the same ID specified by the user during insertion.",
                    "type": "string",
                    "pattern": "[0-9]+-[0-9]+"
                },
                {
                    "description": "The NOMKSTREAM option is given and the key doesn't exist.",
                    "type": "null"
                }
            ]
        }
    }
}