【数据存储】变更审计：表结构变更的审批与记录

---表结构变更：审批流程的受理
function SchemaAudit.apply(operator, tableName, sql)
    -- 变更的类型分类
    local opType = SchemaAudit.classify(sql)
    local risk = SchemaAudit.riskLevel(opType)
    -- 高风险的变更需要双人审批
    if risk == 'high' then
        local approver = SchemaAudit.pendingApproval(
            operator, tableName, sql)
        sendmsg(actor, 1, "高风险变更已提交审批")
        return false
    end
    SchemaAudit.execute(operator, tableName, sql)
    return true
end

---变更的记录：审计流水
function SchemaAudit.record(operator, tableName,
    sql, result, duration)
    SchemaAudit.history[#SchemaAudit.history + 1] = {
        operator = operator,
        table = tableName,
        sql = sql,
        result = result,
        duration = duration,
        at = os.time(),
    }
end