Access previous result of eKuiper rule

[BlancoMY]

Hello everyone,
I'm seeking guidance on a specific requirement of eJuiper. I want to compare the results of a rule from the previous run with the results of the same rule in the current run, and I aim to publish the result only if there's a change in the value.
The goal is to optimize our publishing process and avoid unnecessary updates when the value remains the same. I'm wondering if there's an established method or best practice for achieving this within our current environment. Additionally, any insights or examples related to this scenario would be highly valuable.

Example of graph rule where i want to publish the result only on change of average value of temperature

{
    "id": "rule1Graph",
    "name": "Test",
    "graph": {
        "nodes": {
            "demo": {
                "type": "source",
                "nodeType": "edgex",
                "props": {
                    "format": "json"
                }
            },
            "compFilter": {
                "type": "operator",
                "nodeType": "filter",
                "props": {
                    "expr": "Temperature != nil"
                }
            },
            "window": {
                "type": "operator",
                "nodeType": "window",
                "props": {
                    "type": "SLIDINGWINDOW",
                    "unit": "ss",
                    "size": 30,
                    "interval": 0
                }
            },
            "avgfunc": {
                "type": "operator",
                "nodeType": "aggfunc",
                "props": {
                    "expr": "cast(avg(Temperature), \"string\") as comp_result"
                }
            },
            "pick": {
                "type": "operator",
                "nodeType": "pick",
                "props": {
                    "fields": [
                        "comp_result"
                    ]
                }
            },
            "logOut": {
                "type": "sink",
                "nodeType": "log",
                "props": {}
            }
        },
        "topo": {
            "sources": [
                "demo"
            ],
            "edges": {
                "demo": [
                    "compFilter"
                ],
                "compFilter": [
                    "window"
                ],
                "window": [
                    "avgfunc"
                ],
                "avgfunc": [
                    "pick"
                ],
                "pick": [
                    "logOut"
                ]
            }
        }
    }
}

Thank you for your time and assistance.

[BlancoMY]

Hello everyone,
I've posted a question regarding accessing previous result of eKuiper rule but haven't received any responses yet. I would really appreciate any guidance or assistance on this matter. If anyone has insights or suggestions, I'd be grateful for your input.
Thank you in advance for your help!

[ngjaying]

Try the analytic functions like lag. Check out https://ekuiper.org/docs/en/latest/sqls/functions/analytic_functions.html