hi,

who can give a simple explanation of the difference between update statistics low/medium/high ?

thanks

Hi,
i didn't know it either,
but found an explanation:

2-638 Informix Guide to SQL: Syntax
UPDATE STATISTICS
LOW The database server updates the statistical data in the
systables, syscolumns, and sysindexes system catalog
tables. This mode causes the least amount of information to
be gathered. This mode executes more quickly than the
HIGH and MEDIUM modes.
HIGH In addition to performing the functions of the LOW mode,
the database server updates the data distribution statistics
in the sysdistrib system catalog table. The constructed
distribution is exact. Because of the time required to gather
this information, this mode executes more slowly than the
LOW and MEDIUM modes.
MEDIUM In addition to performing the functions of the LOW mode,
the database server updates the data distribution statistics
in the sysdistrib system catalog table. The database server
obtains the data for the distributions by sampling rather
than by scanning all the rows. This mode executes more
quickly than the HIGH mode but more slowly than the
LOW mode.

Read the valuable article "Understanding and Tuning Update Statistics" at
http://www7b.boulder.ibm.com/dmdd/zo...203miller.html

I find it excellent...


Murat

thanks, Murat