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什么是ETag？ETag作用有哪些

ETag（Entity Tag）是HTTP协议中头部字段之一，它是服务器用来标识特定资源版本的字符串。 ETag的作用主要有以下几个： 1. 缓存控制：通过比较客户端请求中的If-Match或If-None-Match字段和服务器中资源的ETag值来判断资源是否可以使用缓存，从而控制浏览器是否需要重新请求资源。 2. 实现乐观锁定：ETag可以用来实现乐观锁定，即在多用户并发修改同一实体的情况下，可以通过比较各用户提交的If-Match和If-None-Match的值来判断是否可以进行更新操作，从而避免数据冲突。 3. 资源变更检测：当资源发生变化时，服务器会更新ETag的值，客户端可以通过比较新的ETag值和旧的ETag值来检测资源是否发生变化，从而判断是否需要重新加载资源。

Public @ 2023-06-08 14:00:12

移动化培训长沙视频8——辅助移动站点被百度抓取的工具

这个视频的内容不明确，因此无法为您提供答案。请提供更多信息。

Public @ 2023-06-19 12:00:04

摆对姿势，平台君带你玩儿转欧洲杯

欧洲杯激战正酣，站长中的球迷们，伪球迷们，这个夏天平台君陪你一起过！站长平台启动一系列欧洲杯活动，不仅可以助你挖掘潜力流量、脑洞大开，甚至还有可能成为赛事预测大神！目测一大波欧洲杯活动正在向你砸来，请接招！活动一：欧洲杯流量掘金，大比拼！欧洲杯大量新增免费流量，怎能不眼馋？怎样才能合理的分到一杯羹？欧洲杯内容专题？活动专题？还是优化下标题？各家有各家的高招，只要『摆对姿势』，欧洲杯大量免费流量正滚

Public @ 2009-03-09 16:06:30

我的网站同时有多种格式。需要都列出来吗？

请在 Sitemap 中只列出一种格式的网址。包含多种格式的网址可能会导致抓取工具无法完整地抓取网站。

Public @ 2010-02-06 16:11:54

什么是ETag？ETag作用有哪些

ETag 是一种用于标识网络资源的字符串。ETag 是由服务器为每个资源生成的，并且在资源内容发生变化时会改变。 ETag 主要用于缓存控制和条件请求。以下是 ETag 的一些作用： 1. 缓存验证：当客户端请求资源时，可以在请求头中通过 If-None-Match 字段将上一次请求中得到的 ETag 值发送给服务器。服务器可以根据这个值来判断资源是否发生了变化。如果 ETag 值匹配，服务器

Public @ 2023-07-30 17:50:26

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[ DB ] CONNECT:[ UseTime:0.020838s ] mysql:dbname=briline.net;host=106.14.77.182;port=3306;charset=utf8
[ SQL ] SHOW COLUMNS FROM `ob_config` [ RunTime:0.014961s ]
[ SQL ] SELECT * FROM `ob_config` [ RunTime:0.014132s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_config', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 25, 'extra' => NULL, ) ]
[ SQL ] SHOW COLUMNS FROM `ob_hook` [ RunTime:0.014531s ]
[ SQL ] SELECT `id`,`name`,`addon_list` FROM `ob_hook` [ RunTime:0.013864s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_hook', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 3, 'extra' => NULL, ) ]
[ SQL ] SHOW COLUMNS FROM `ob_article` [ RunTime:0.014929s ]
[ SQL ] SELECT * FROM `ob_article` WHERE `id` = 8620 LIMIT 1 [ RunTime:0.014068s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'const', 'possible_keys' => 'PRIMARY', 'key' => 'PRIMARY', 'key_len' => '4', 'ref' => 'const', 'rows' => 1, 'extra' => NULL, ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='cate' order by times desc limit 15 [ RunTime:0.014365s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using filesort', ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='tags' order by times desc limit 100 [ RunTime:0.014404s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using filesort', ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='tags' order by rand() limit 30 [ RunTime:0.014552s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using temporary; Using filesort', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `id` = 8620 LIMIT 1 [ RunTime:0.013977s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'const', 'possible_keys' => 'PRIMARY', 'key' => 'PRIMARY', 'key_len' => '4', 'ref' => 'const', 'rows' => 1, 'extra' => NULL, ) ]
[ SQL ] update `ob_article` set views=views+2 where id=8620 [ RunTime:0.014834s ]
[ SQL ] SELECT COUNT(*) AS tp_count FROM `ob_article` WHERE `category_id` = 12 AND `cate` = '威海百度搜索资源平台' AND `status` <> -1 LIMIT 1 [ RunTime:0.021631s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 9562, 'extra' => 'Using where', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `category_id` = 12 AND `cate` = '威海百度搜索资源平台' AND `status` <> -1 ORDER BY rand() LIMIT 0,2 [ RunTime:0.042812s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 9562, 'extra' => 'Using where; Using temporary; Using filesort', ) ]
[ SQL ] SELECT COUNT(*) AS tp_count FROM `ob_article` WHERE `category_id` = 12 AND `tags` = '威海Sitemap' AND `status` <> -1 LIMIT 1 [ RunTime:0.025071s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 9562, 'extra' => 'Using where', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `category_id` = 12 AND `tags` = '威海Sitemap' AND `status` <> -1 ORDER BY rand() LIMIT 0,2 [ RunTime:0.032115s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 9562, 'extra' => 'Using where; Using temporary; Using filesort', ) ]

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