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SQL Anywhere 11.0.1 (Français) » SQL Anywhere Server - SQL Reference » System Objects » System procedures » Alphabetical list of system procedures

 

sa_get_dtt_groupreads system procedure

Estimates and reports the cost of issuing group reads on the database server.

Syntax
sa_get_dtt_groupreads( dbspace_id )
Arguments
  • dbspace_id   Use this UNSIGNED SMALLINT parameter to specify the database file ID.

Remarks

You can obtain the dbspace_id from the SYSDBSPACE system view. The estimates returned by the sa_get_dtt_groupreads system procedure are part of the cost model, and are used to select group reads of appropriate sizes during operations such as sorting.

This procedure, intended for internal diagnostic purposes, retrieves data from the ISYSOPTSTAT system table. Rows are not returned if the specified dbspace does not have any estimates recorded in SYSOPTSTAT. To tailor estimates for specific hardware devices, execute the following statement:

ALTER DATABASE CALIBRATE GROUP READ;
Result set
Column name Data type Description
GroupSize UNSIGNED INTEGER Size, in pages, of disk over which random access takes place.
ReadTime FLOAT Amortized cost, in microseconds, of reading one page.
Permissions

None

Side effects

None

See also