Fragment Metadata

Each fragment of an array contains metadata about the fragment, including the number of cells, the file offsets, and aggregate and indexing information.

Each fragment includes a special fragment metadata file inside its folder. This files contains necessary index information about the fragment for TileDB to implement efficient read operations. Some of the information the fragment metadata file stores includes:

• The number of total cells in the fragment.
• The file offsets of each data tile for each attribute and dimension.
• Aggregate information for each data tile.
• Indexing information (such as the R-tree in sparse arrays).

For more information about the format of the fragment metadata file, visit the Storage Format Spec section.

Over time, the number of fragments in an array increases with each write you perform, which may have a negative impact on performance. To reduce these effects, TileDB supports consolidation of fragments, as well as fragment metadata. Consolidation of fragment metadata generates a consolidated fragment metadata file, which combines the metadata of multiple fragments in one, significantly boosting the read performance.