mi_integer am_beginscan(MI_AM_SCAN_DESC *scanDesc)

scanDesc

points to the scan descriptor.

The functions that the access method supplies for am_beginscan, am_getnext, and am_endscan compose the main scan-management routines. In its turn, the am_beginscan purpose function can perform the following operations:

• Obtain the qualification descriptor from the scan descriptor
• Parse the criteria in the qualification descriptor

  For a more detailed discussion, refer to Processing Queries.

• Determine the need for data type conversions to process qualification expressions
• Based on the information in the qualification descriptor, initiate a search for data that fulfills the qualification
• Allocate PER_COMMAND memory to build user data and then store the user data in the scan descriptor for the am_getnext function

  For more information about memory allocation, refer to Storing Data in Shared Memory.

You can also choose to defer any processing of qualifications until the am_getnext function.

MI_OK indicates success. MI_ERROR indicates failure.

See the descriptions of:

• Purpose functions am_endscan, am_getnext, and am_rescan
• Optimizing Queries