I want to show a user only the content he has not viewed yet. I considered storing a string containing the ids of the items separated by ',' that a user has viewed but i thought i won't know the possible length of the string. The alternative i could find was to store it like a log. A table like
我想向用户显示他尚未查看的内容。我考虑过存储一个字符串，其中包含用户已查看的'，'分隔的项目的ID，但我想我不知道字符串的可能长度。我能找到的替代方案是将其存储为日志。像一张桌子
user_id | item_id
1 | 1
2 | 2
1 | 2
Which approach will be better for around ten thousand users and thousands of items.
对于大约一万个用户和数千个项目，哪种方法更好。
1 个解决方案
#1
1
A table of pairs like that would be only 10M rows. That is "medium sized" as tables go.
像这样的对的表只有10M行。这是表中的“中等大小”。
Have
有
PRIMARY KEY(user_id, item_id),
INDEX(item_id, user_id)
And, if you are not going past 10K and 1K, consider using SMALLINT UNSIGNED (up to 64K in 2 bytes). Or, to be more conservative, MEDIUMINT UNSIGNED (up to 16M in 3 bytes).
并且，如果您没有超过10K和1K，请考虑使用SMALLINT UNSIGNED（2字节最多64K）。或者，更保守一点，MEDIUMINT UNSIGNED（3字节最多16M）。
#1
1
A table of pairs like that would be only 10M rows. That is "medium sized" as tables go.
像这样的对的表只有10M行。这是表中的“中等大小”。
Have
有
PRIMARY KEY(user_id, item_id),
INDEX(item_id, user_id)
And, if you are not going past 10K and 1K, consider using SMALLINT UNSIGNED (up to 64K in 2 bytes). Or, to be more conservative, MEDIUMINT UNSIGNED (up to 16M in 3 bytes).
并且，如果您没有超过10K和1K，请考虑使用SMALLINT UNSIGNED（2字节最多64K）。或者，更保守一点，MEDIUMINT UNSIGNED（3字节最多16M）。