4 ms·

Uhh. A b tree is a self balancing binary (search) tree.

• coding123 5y ago
  Not binary, it can and generally has more than 2 children per node. That's the main difference.
• broken8ball 5y ago
  Binary implies two. Both B-trees and BSTs exist in the universe of m-ary trees. A BST and a B-tree would be equivalent only if the branching factor of the B-tree was set to 2, but practically this is rarely the case with indexes, given that a higher branching factor is generally more favorable to lookup times (“block accesses”) since the hight of the B-tree is reduced as m increases.
  • masklinn 5y ago
    > practically this is rarely the case with indexes Seems like it would be extremely odd to have a 2-2 btree, you’d just get a significantly more complicated BST no? I’d figure you’d want to fill a cacheline with something typical-ish, so probably at least 4 (this way if you have 4 children and 3 keys, the keys are 8 bytes and the child links are straight pointers your node is 56 bytes and you can add some metadata e.g. a bitmap). Apparently Rust’s BTreeMap is a 6-11 btree but I don’t know how they picked the branching factor.