当我尝试使用class SensorInfoWindow extends React.Component {
handleIconClick = () => {
// do stuff here
}
componentDidMount() {
this.addClickHandlers();
}
componentDidUpdate() {
this.addClickHandlers();
}
addClickHandlers = () => {
const keys = Object.keys(this.refs);
for(let i=0; i<keys.length; i++) {
const key = keys[i];
let element = this.refs[key];
if (element !== undefined)
element.addEventListener('click', this.handleIconClick);
}
}
render() {
const { thissensor, allsensors } = this.props;
let divsToAddHandlersTo = [];
const sensorkeys = Object.keys(allsensors);
for (let i=0; i<sensorkeys.length; i++) {
divsToAddHandlersTo.push(
<div
ref={'stringref' + i}
/>
{/* children here, using InfoBox */}
</div>
);
}
return (
<div>
{divsToAddHandlersTo}
</div>
);
}
}
查询postgres时，即使从一个表进行简单的psql查询也要花费约1.5s。当我在postgres控制台中时，没有问题，查询将在100毫秒内执行。什么会导致这种延迟？
SELECT仅供参考：表格中有11个条目
答案 0 :(得分：0)
延迟是建立数据库连接所花费的时间。
1.5秒相当la脚。但这不必成为杀手er，因为您应该使用连接池并保持数据库会话打开。
可以肯定的是，您可以将结果与
进行比较psql -U postgres@user -h my-server.postgres.database.azure.com database_name <<EOF
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
SELECT count(*), clock_timestamp() FROM table_name;
EOF
那应该更快。区别在于连接时间。