Be careful not to index on a foreign key, i.e. do not index a field that
is a tlookup or trans to another file.
An example is if custno is on the order header,and you xlate it to
order.line, do not index order.line by custno. It will not update
properly.
U2 indexing is such a breath of fresh air over the D3 indexing I was
using for a few years recently.
[email protected] wrote:
Our primary application hasn't needed the performance gains offered by
indexing, but our database has grown large and complex enough that we're
looking at it seriously. Having only dabbled with indexing in test
environments, I've got a few general and best practice questions. I've
seen some comments in the archives on some of the pitfalls, e.g. the
dangers of indexing remote files and indexing on correlatives with
subroutines. But posts I found are at least a year old. I'm guessing there
may be updated information out there. Feel free to point out that
everything I'm asking is in the archives and send me there.
Some questions:
* Are there guidelines for how many indices is too many for one file
(assuming disk space isn't an issue)?
* Does BUILD.INDEX with the ONLINE parameter work as advertised? Can it
really be run while the file is being updated?
* How about data consistency? I seem to remember there being concerns in
earlier days of an index not always being updated correctly.
* How about indexing multi/subvalued fields? I don't know that we'd want
to, but is it advisable? Valuable?
* We use EMC to clone our production account so we can run nightly reports
off-line. The account is renamed in this process. Might that cause any
index issues? The clone is read-only, so there are no updates, just
queries.
* I've seen mention of index corruption. Is it obvious when an index is
corrupt or can it be subtle? If subtle, are there ways to detect issues
before our users do?
* Performance is what we're after, but are there benefits to indexing
other than performance?
AIX 5.3
UniData 7.1
All thoughts, comments, observations are most appreciated.
Brad Schrag
U.S. BANCORP made the following annotations
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