how to use blob pattern as an alternative of EAV -

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in literature , on forums people eav evil , sugest using serialized lob pattern alternative of eav, don't concrete how use it.

i wonder how overcome problems using blob pattern alternative of eav. let’s assume store custom fields of entity in field custom_fields string example in json tihis: {customfield1: value1, customfield2: value2, …, customfieldn: valuen} let's assume table subscribers has fields: id, email, custom_fields (where custom fields stored)

how overcome following problems: 1. how seach seperate custom fields, example, find entities conditions custfield1 = value1 , customfield2 = value2? 2. how mantain data integrity, example, if delete custom field entity how delete values oif these custom fields in entity?


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