Walter Meester
HoogkarspelNetherlands
General information
Category:
Databases,Tables, Views, Indexing and SQL syntax
Hi George,
>>I'm not saying that fragmentation is always good, but I neither think that fragmentation is always bad either. In certain situations fragmented files could perform better than unfragmented files. Unfortunately we don't have much control on how tables are fragmented, so talking about advatages and disadvantages is purely an academic issue.
>See my reply to Jim.
I'm not sure to which reply you're reffering too, but I agree that in most cases fragmentation at the least is not helpfull in improving performance.
However, if you look at specific cases where 90 % of the disk I/O has to do with data retrieval of logical grouped record, suchs as 'dossiers' (e.g. patient records in health information systems, insurance dossiers etc), the fragmentation of the logical 'dossiers' theoretically is far worse than fragmentation of the physical tables.
You've got to damn well identify such case, before you draw your conclusions in order to fragment or not to fragment tables in your databases.
Walter,
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