看来就这个内存的问题， 我把内存调大就快了，感谢大佬！！
mysql> SET tidb_mem_quota_query = 8 << 30;
Query OK, 0 rows affected (0.00 sec)
mysql> SET tidb_mem_quota_query = 8 << 30;
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT xpost.postid, xpost.facetid, xpost.entryid, xpost.title, xpost.url, xpost.abstract, xpost.click, xpost.reply, xpost.repost, xpost.praise, xpost.collect, xpost.wordscount, xpost.siteid, xpost.domain, xpost.author, xpost.author_id, xpost.posttime, xpost.include_t, xpost.type, xpost.source, xpost.hidden, xpost.sourcetype, xpost.crisis_post, xpost.ontop, xpost.type_rank, xpost.pos_type_rank, xpost.noise_rank, xpost.device, xpost.is_origin, xpost.is_top, xpost.media_type, xpost.author_type, xpost.content_type, xpost.client_type, xpost.industry, xpost.tags, xpost.post_type, xpost.type_reason, xpost.update_time, xpost.origin_source, xpost.media_id, xpost.w_level, xpost.watch, xpost.keywordcount, xpost.location, xpost.is_comment, xpost.text, xpost.spider_time, xpost.process_time, xpost.tidb_in_time FROM xpost FORCE INDEX (idx_xpost_entryid) WHERE (xpost.entryid IN (4856577, 4855938, 4856069, 4855686, 4856079, 4857488, 4857618, 4855699, 4856087, 4855966, 4854815, 4855201, 4855714, 4855076, 4851496, 4855083, 4854830, 4856371, 4855608, 4851514, 4857916, 4852797, 4855743, 4851522, 4855748, 4855365, 4851526, 4855624, 4855626, 4856654, 4856018, 4855635, 4855764, 4855637, 4855766, 4854986, 4857305, 4855134, 4855135, 4857706, 4857454, 4855408, 4857211, 4856062) AND (1) AND xpost.hidden IN (-2, -1, 0, 2, 3, 4)) ORDER BY xpost.posttime DESC;
1244055 rows in set (30.22 sec)
mysql>
mysql>
mysql>