I wish to get to know index organization. Imagine there exists a table with 2 posts:
CREATE TABLE user( name varchar(100) ,age int)
We wish to create a catalog:
CREATE INDEX IDX_MultiColIdx on user(name,age)
Wouldso would B-Tree index organization seem like?
Just in case of 1 column, say, age, the business is obvious: every non-leaf node would contain some integer secrets which may be utilized for any search. Which values contain nodes in our *IDX_MultiColIdx* B-Tree index?
Which values consists of nodes in our *IDX_MultiColIdx* B-Tree index?
age and also the row pointer (
ROWID or clustered key, with respect to the table organization), sorted lexicographically.
Exactly how they'll be saved, is dependent around the datatype and database system.
CHAR is saved right-padded with spaces as much as its size, while
VARCHAR is prepended using its length.
MyISAM plus some other engines may use key compression: the matching areas of some secrets are just saved once, and also the other secrets only keep varying parts, such as this:
Hamblin Hamblin, California Hamblin (surname) Hambling Baronets Hambly Hambly Arena Hambly Arena Fire Hambo Hambo Lama Itigelov Hambok Hambone
is going to be saved as:
Hamblin , California  (surname) g Baronets Hambly  Arena  Arena Fire Hambo  Lama Itigelov k ne
[x] means "take leading
x figures in the previous key"
I suppose you are asking concerning the internal database implementation since you mention 'non-leaf nodes'.
The inside nodes inside a b-tree don't need to keep full key they only have to store separator secrets. Prefix and suffix compression imply that interior nodes can be quite dense, and for that reason lessen the height from the b-tree and for that reason improve efficiency.
For instance, given a catalog using the consecutive secrets <'A very lengthy string', 314159> and <'Not exactly the same string', 9348>, all of the interior node must represent may be the separation between individuals individuals secrets, which may be symbolized in one character. Similarly, once the secrets to become separated within the interior node possess a common prefix, that prefix only need be saved once and the stage where they diverge symbolized.
The leaf nodes have to keep full key values, and may be saved inside a linked list for key order traversal. Leaf node pages could be compressed by utilizing prefix compression or any other strategies to further lessen the tree height.
For any good reference about this, see "Transaction Processing: Concepts and methodsInch by Grey &lifier Reuter, and stick to the references if you would like more detail.