Technical Note: Indexing for Envision Datasets

Technical information about Indexing for Envision Datasets.

Supported Envision Versions: 1.0, 1.1, 1.2

MongoDB limitation on size of index entries / workaround

When a dataset is defined in Envision, accompanying collections are generated in the MongoDB METRIC_RAW_DATA and METRIC_ROLLUP_DATA databases.

These collections will include generated indexes with names of the format <dataset name> UIDX, and will consist of all dimensions defined for the dataset.

MongoDB restricts the size of entries in such indexes to less than 1024 bytes; it is possible that records collected for the dataset will exceed this limit, and if that happens those records will not be written to the collection.

Because of this limitation, it might be necessary to modify the MongoDB <dataset name> UIDX indexes for a dataset that has many (or lengthy) dimensions to include only those dimensions that will be used often in Envision charts defined on the dataset.

If this happens, the indexes should be manually updated to exclude dimensions that are not critical to chart performance.