Update documentation for log_action table about hash and name #14883
Labels
answered
For when a question was asked and we referred to forum or answered it.
Milestone
While doing some research on the log_action table, I discovered that the chance of a collision of a crc32 hash is pretty high:
https://preshing.com/20110504/hash-collision-probabilities/ (see at the bottom "Small Collision Probabilities")
In my setup we have about 182 million rows in log_action which means the chance of a collision is already way higher than 1 out of 2 if I am not mistaken.
So it seems like it is important that sql queries always match on hash and name.
Maybe this information should be added to the documentation somewhere (https://developer.matomo.org/guides/persistence-and-the-mysql-backend)
Maybe it also makes sense to add some info about always querying for type, hash and name at the same time so that the index can be used.
The text was updated successfully, but these errors were encountered: