Split page
Point lookups are similar to B-trees, except that because pages are linked in only one direction,
Point lookups are similar to B-trees, except that because pages are linked in only one direction,
the Database Engine follows right page pointers, where each nonleaf page has the highest
value of its child, rather than lowest value as in a B-tree.
If a leaf-level page has to change, the Database Engine doesn’t modify the page itself. Rather,
the Database Engine creates a delta record that describes the change, and appends it to the
previous page. Then it also updates the page map table address for that previous page, to the
address of the delta record that now becomes the physical address for this page.
There are three different operations that can be required for managing the structure of a Bw-
tree: consolidation, split, and merge.
A long chain of delta records can eventually degrade search performance as it could require
long chain traversal when searching through an index. If a new delta record is added to a chain
that already has 16 elements, the changes in the delta records are consolidated into the
referenced index page, and the page is then rebuilt, including the changes indicated by the
new delta record that triggered the consolidation. The newly rebuilt page has the same page
ID but a new memory address.
An index page in Bw-tree grows on as-needed basis starting from storing a single row to
storing a maximum of 8 KB. Once the index page grows to 8 KB, a new insert of a single row