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Indexes and special data types

 
sourabh girdhar
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Hi

I have not got opportunity yet to work on spatial databases but I am curious to learn about them. Does this book contains details about how data storage in spatial database differs from normal database.
What happens to special datatypes like LOB,BLOB,CLOB etc..
How indexes are maintained in spatial databases.
 
chris webster
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Until the authors are able to reply, you might find some basic information on these questions in my post on another thread.

Chris
 
sourabh girdhar
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NIce article. Very well explained.

Thanks Cris
 
chris webster
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Here's some info on how PostGIS indexes spatial data.

In terms of data types, PostGIS (or Oracle Spatial) simply adds some extra data types to your PostgreSQL (or Oracle) RDBMS. All the regular data types are still there.

Spatial data tends to come with a lot of scalar (non-spatial) attributes e.g. a table listing hospitals might include the location (spatial data) but also the name, street address, phone number, size etc. So if you include a spatial data column on a particular table, it becomes a spatial data table and you can apply various spatial functions to the spatial elements of the data e.g. find the nearest hospital to your current location.

If there are no spatial data columns, then it's just a regular table. In both cases, you can still do all the usual SQL stuff on the non-spatial elements in the data. And of course you can combine spatial and non-spatial operations e.g. find the nearest hospital with a name that contains "X" (no idea why you would do this, of course!), which is one of the many benefits of using a spatial database.
 
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