5.1.5 Smart Scan Metadata Sharing

During Smart Scan operations, Oracle Database sends query metadata to the Exadata Storage Servers. The query metadata contains information like predicated columns, projected columns, predicates, database session information, bloom filters, and so on, which is required to offload the query to the storage servers. Historically, during parallel query execution, each Oracle Database parallel query server process sends serialized and compressed query metadata to the storage server, where it is uncompressed and deserialized before use. Furthermore, for each parallel query, a significant portion of the metadata is common to all of the parallel query server processes.

Starting with release 21.2.0, Oracle Exadata System Software shares common query metadata across Smart Scan sessions belonging to the same parallel query. This feature reduces the memory and processing footprint for parallel queries in Exadata Storage Server. In turn, the saved resources can support other work and increase the overall system throughput. The benefit is greatest for sophisticated operations that typically require more metadata, such as join queries using Bloom filters, data mining models, external tables, and tables with JSON/XML types.

Minimum requirements:

• Oracle Exadata System Software release 21.2.0