Tag
access-paths
- Jun 25, 2026 Fanout, Height, and Why B-Trees Stay Shallow How page size, key width, and pointer width determine the branching factor of a B-tree, and why three or four levels cover billions of keys. databases
- May 17, 2026 Bitmap Index Scans and the Order of Heap Fetches Why a plan collects row identifiers into a bitmap before fetching rows, how the bitmap is compressed and ordered, and when losing row order is acceptable. databases
- Nov 13, 2024 The Crossover Between an Index Scan and a Sequential Scan Why fetching a few percent of a table by index can cost more than reading all of it, how physical correlation moves the crossover point, and what bitmap scans change. databases
- Jul 3, 2024 Physical Operator Selection and Access Path Mechanics What distinguishes a sequential scan from an index scan, a bitmap heap scan from an index-only scan, and how each access path decides when to stop reading. databases
- Jan 1, 2024 Clustered and Secondary Access Paths and the Cost of a Row Fetch What separates a clustered index from a secondary index, how a secondary lookup pays for a second descent, and why covering indexes change the plan. databases