Database Reference
In-Depth Information
Query and scan operations
The query operation is a very important operation that allows us to fetch specific items
from the given table. It needs a primary input and an optional start key to compare with the
list of items. The query fetches all matching entries to the input from a given table. You can
also use comparison operations, such as greater than, less than, contains, between, and so
on to narrow down the result set. Data returned from a query or scan operation is limited to
1 MB. If it does not find any matching items with respect to a given input key, it returns an
empty set.
Query results are always sorted in the order of the range key value. By default, the order of
sorting is ascending. If a table has secondary index, then the query operation can be per-
formed on it as well.
The scan operation checks every individual item for a given table. We can specify the filter
criteria in order to manage the search results after the scan gets completed. A scan filter
normally consists of the list of attribute values to be compared with and the comparison op-
erator. Like the query operator, the scan also puts the maximum result size as 1 MB.
