Class DBIndex

source code

                   object --+            
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 base.structure.StructureBase --+        
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                   object --+   |        
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           base.common.Parser --+        
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base.structure.ParseableStructure --+    
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             base.structure.Structure --+
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                                       DBIndex

A description of an index in the database.

In real databases, indices may be fairly complex things; still, the most common usage here will be to just index a single column:

       <index columns="my_col"/>

To index over functions, use the character content; parentheses are added by DaCHS, so don't have them in the content. An explicit specification of the index expression is also necessary to allow RE pattern matches using indices in character columns (outside of the C locale). That would be:

       <index columns="uri">uri text_pattern_ops</index>

(you still want to give columns so the metadata engine is aware of the index). See section "Operator Classes and Operator Families" in the Postgres documentation for details.

For pgsphere-valued columns, you at the time of writing need to specify the method:

       <index columns="coverage" method="GIST"/>

To define q3c indices, use the ``//scs#q3cindex`` mixin; if you're devious enough to require something more flexible, have a look at that mixin's definition.

If indexed columns take part in a DaCHS-defined view, DaCHS will not notice. You should still declare the indices so users will see them in the metadata; writing:

       <index columns="col1, col2, col3"/>

is sufficent for that.