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Handling large data sets for web apps
Message
De
01/08/2001 09:26:46
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivie
 
 
À
01/08/2001 09:10:26
Information générale
Forum:
Visual FoxPro
Catégorie:
West Wind Web Connection
Divers
Thread ID:
00535271
Message ID:
00538271
Vues:
11
>We are not running across a network, just from the local hard drive but because we have been gradually scaling up, the could be a possibility in the near future.

Unfortunately, it seems that my comments sometimes don't apply on the local drive, only over the network. Full Optimization, on a local drive and with relatively few records, may actually be worthwhile. I remember testing some years ago; queries were actually faster with the index on deleted() (which I now avoid). The situation may change quite a bit, though, with hundreds of thousands of records (instead of, say, one thousand), or over a network.

>As you have stated though, the data is changing all the time. Is the penalty that I am getting now about .1 to .2 worth constantly monitoring the data basically doing what Oracle or SQL Server would do - Kind of a crude statistics. I don't know.

The Database Server has to do statistics. On the other hand, you, as a programmer, can do some intelligent guessing in advance: what data do you plan to place in a field? Of course, some statistics every now and then, to check your initial guess, may be useful. The following query counts how many times each value of KeyField is used in SampleTable:
select KeyField, count(*) as TimesUsed;
  from SampleTable;
  group by KeyField;
  order by TimesUsed descending
>As to your comment about Oracle, I'm not sure why you would ever use rule-based optimization unless the overhead for keeping statistics outweighs the benefits.

Yes, I understand cost-based optimization is the preferred method. But I don't actually use Oracle - I only did some reading. Therefore, I wouldn't know for sure.

Hilmar.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
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