Questions about the transfer speed of PHP read remote database

PHP read remote database transfer speed problem?
I now have some pages to hang on to someone else's website, and then to read data from my database to those pages display, if the direct mysql_connect () connection to read the data will not be very slow? Will there be a big problem? Because you also want to buy items on those pages, and then jump to our back-office payment ...
Seek the Master's opinion ...

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Hang it to someone else's website and then read the data from my database
Remote operation must be slower, that's all.
The problem is that remote operations require open access, with a slight careless exposure of your data to each other.
This should not be what you want, because there are still payments to our backstage
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I understand what you mean, you want to put the merchandise on your platform on the other merchant's website. In fact, you do not need to open MySQL permissions, because the other people have access to the database is not safe for you.
You can learn about other ways of interacting with data, such as XML or webserver, and you provide them with an interface that is much better than the permissions you give them directly to their database operations.
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If it is not the same engine room, under the same switch, the speed is very slow, the best way is to do an API interface to each other to let the other side to tune

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