借助MySQL触发器，以及为MySQL 5.1 编写的扩展插件函数，来让TCSQL当MySQL的从库：
json_object()、 urlencode()、http_post()
接下来是一个示例：通过MySQL命令行连接到MySQL服务器，执行以下SQL，对sns_feed表创建三个MySQL触发器：sns_feed_insert、sns_feed_update、sns_feed_delete，当MySQL的sns_feed表发生增、删、改操作时，自动将修改的记录内容通过HTTP POST到TCSQL数据库(192.168.8.34:3888)。
TCSQL“从库”Insert触发器
DELIMITER |
DROP TRIGGER IF EXISTS sns_feed_insert;
CREATE TRIGGER sns_feed_insert
AFTER INSERT ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_json = (SELECT json_object(feedid as pkey,appid,icon,uid,username,dateline,friend,hash_template,hash_data,title_template,title_data,body_template,body_data,body_general,image_1,image_1_link,image_2,image_2_link,image_3,image_3_link,image_4,image_4_link,target_ids,id,idtype,hot) FROM sns_feed WHERE feedid = NEW.feedid limit 1);
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', 'command=insert', urlencode(@tcsql_result_json)));
END |
DELIMITER ;
DROP TRIGGER IF EXISTS sns_feed_insert;
CREATE TRIGGER sns_feed_insert
AFTER INSERT ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_json = (SELECT json_object(feedid as pkey,appid,icon,uid,username,dateline,friend,hash_template,hash_data,title_template,title_data,body_template,body_data,body_general,image_1,image_1_link,image_2,image_2_link,image_3,image_3_link,image_4,image_4_link,target_ids,id,idtype,hot) FROM sns_feed WHERE feedid = NEW.feedid limit 1);
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', 'command=insert', urlencode(@tcsql_result_json)));
END |
DELIMITER ;
TCSQL“从库”update触发器
DELIMITER |
DROP TRIGGER IF EXISTS sns_feed_update;
CREATE TRIGGER sns_feed_update
AFTER UPDATE ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_json = (SELECT json_object(feedid as pkey,appid,icon,uid,username,dateline,friend,hash_template,hash_data,title_template,title_data,body_template,body_data,body_general,image_1,image_1_link,image_2,image_2_link,image_3,image_3_link,image_4,image_4_link,target_ids,id,idtype,hot) FROM sns_feed WHERE feedid = OLD.feedid limit 1);
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', 'command=insert', urlencode(@tcsql_result_json)));
END |
DELIMITER ;
DROP TRIGGER IF EXISTS sns_feed_update;
CREATE TRIGGER sns_feed_update
AFTER UPDATE ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_json = (SELECT json_object(feedid as pkey,appid,icon,uid,username,dateline,friend,hash_template,hash_data,title_template,title_data,body_template,body_data,body_general,image_1,image_1_link,image_2,image_2_link,image_3,image_3_link,image_4,image_4_link,target_ids,id,idtype,hot) FROM sns_feed WHERE feedid = OLD.feedid limit 1);
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', 'command=insert', urlencode(@tcsql_result_json)));
END |
DELIMITER ;
TCSQL“从库”delete触发器
DELIMITER |
DROP TRIGGER IF EXISTS sns_feed_delete;
CREATE TRIGGER sns_feed_delete
AFTER DELETE ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', concat('command=delete&where=pkey:NUMEQ:', OLD.feedid), ''));
END |
DELIMITER ;
DROP TRIGGER IF EXISTS sns_feed_delete;
CREATE TRIGGER sns_feed_delete
AFTER DELETE ON sns_feed
FOR EACH ROW BEGIN
SET @tcsql_result_eval = (SELECT http_post('192.168.8.34', '3888', concat('command=delete&where=pkey:NUMEQ:', OLD.feedid), ''));
END |
DELIMITER ;
TCSQL的数据update更新优化
TCTDB+Tokyo Tyrant时，如果只更新一条记录中的某个字段的值，PHP客户端需要先读回Tokyo Tyrant中该记录的全部字段内容到一个PHP数组，再修改此数组中该字段的值，最后再将该数组写回Tokyo Tyrant ，来回通过网络传输记录全部字段内容，速度慢、效率低。
TCSQL可以对部分字段内容进行更新，在TCSQL内部处理完成修改操作，没有不必要的TCP传输。
