Table
An SQL table or physical file is the base object for a query. It represents the source of the data used to produce the result set for the query. It is created by the user and specified in the FROM clause (or OPNQRYF FILE parameter).
The optimizer will determine the most efficient way to extract the data from the table in order to satisfy the query. This may include scanning or probing the table or using an index to extract the data.
Visual explain icon:
- Table scan
A table scan is the easiest and simplest operation that can be performed against a table. It sequentially processes all of the rows in the table to determine if they satisfy the selection criteria specified in the query. It does this in a way to maximize the I/O throughput for the table. - Table probe
A table probe operation is used to retrieve a specific row from a table based upon its row number. The row number is provided to the table probe access method by some other operation that generates a row number for the table.