Re: SQL Hidden indexes originating from constraints

Hi,



Beware, I'm in deep water and may have misunderstood most of what I'm
trying
to explain below:



Trying to analyze a bunch of ODBC requests for performance improvements and
my starting point is to compare where-clauses to available indexes.

Found a schema with a bunch of large tables - and to my surprise NO
indexes.
DSPLIB - no. DSPDBR - no. Went graphical at
:2001/Databases/Schemas/Schema/Indexes - no.

However I found a bunch of constraints named Q_* that can be found at
2001:/ Databases/Schemas/Schema/Tables/Table-right-click/Show indexes.



It seems to me that the SQL manager creates an index for every constraint
being defined and if I run an sql-statement in Visual Explain it actually
uses the Q_* index.



Questions:

Anyone knows the reason those indexes are not showed up as indexes unless I
right click on the specific table name and click Show Indexes?

Why are they hidden? I can't get usage information etc.

If I'm reasonably right about these indexes being used it seems appropriate
to add a lookup to qsys2.syskeycst in my DB relations analyze program.



If I'm going to loose more hair on this I probably have to start with arms
and legs..



Thanks!



Stefan

--


Stefan Tageson



Mobile +46 732 369934











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