Implicit pass-through
(IP) is the process of translating SQL query code into equivalent
data source-specific SQL code so that it can be passed directly to
the data source for processing. IP improves query response time and
enhances security.
The performance benefits
that are provided by IP can be divided into two primary categories:
data transfer volume reduction and leveraging of data source-specific
capabilities. The volume of data being transferred is reduced by performing
the query on the data source. The number of rows that are transferred
from the data source to FedSQL can be significantly reduced, thereby
decreasing the overall query processing time. The leveraging of data
source-specific capabilities, such as massively parallel processing,
are specific to a data source. Other examples of special capabilities
are advanced join techniques, data partitioning, table statistics,
and column statistics. These capabilities often allow the data source
to perform the SQL query more quickly than FedSQL.
The security benefit
of IP is that every part of an IP query that can be processed is processed
on the data source side. This eliminates the need to have its associated
tables, which might contain sensitive information, transmitted over
to the FedSQL side for query processing.