In this requirement object A and object B are not related.
Since we need to fire the update on object A based on field change on object B and record count is around 10,000, trigger will not be good option. Therefore need a way out to capture the field change and update the records then only

Thanks

I have a picklist with an onchange event bound to it.
When I select a value in the picklist, I get the following error message :
This page has an error. You might just need to refresh it. Error in $A.getCallback() [b.run is not a function] Failing descriptor: {lightning:select}

Component :
 

<aura:component>
    
    <aura:attribute name="colors" type="String[]"/>
    <aura:attribute name="selectedColor1" type="String"/>
    
    <aura:handler name="init" value="{!this}" action="{!c.loadOptions}" />
    
    <lightning:select aura:id="select1-id" value="{v.selectedColor1}" onchange="{c.onChangeColor}" name="picklist1" label="Select a Color"  >
        <option value="">-- None --</option>
        <aura:iteration items="{!v.colors}" var="color">
            <option value="{!color.value}" text="{!color.label}"></option>
        </aura:iteration>
    </lightning:select>
    
</aura:component>

Controller :

({
    loadOptions: function (component, event, helper) {
        var opts = [
            { value: "R", label: "Red" },
            { value: "G", label: "Green" },
            { value: "B", label: "Blue" }
         ];
         component.set("v.colors", opts);
    },
    onChangeColor: function (component, event, helper) {
        //var myColor = event.getSource().get("v.value");
        //var test;
    }
})