Multicolumn BTree indexes

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Multicolumn BTree indexes

Antoine Gourlay
Hi everyone,

I just committed [1] to trunk support for multiple-column BTree indexes.

At the java API level, all methods of the IndexManager that took a field
name now can take an array of field names, which obviously indexes those
methods. The usual range queries (possibly reduced to a lookup for a
single value) are allowed.

At the SQL level, the syntax was expanded to support creating and
deleting multiple-column indexes, i.e. this is valid now: "CREATE INDEX
ON myTable(field1, field2, field3)" and same for DROP INDEX.

Only non-geometry column are supported, and only types that can be
sorted (numeric, string and date/time types).

Erwan, does this fits what you needed for your graph analysis? Have a
look into IndexManagementTest for two use cases.

The query planner currently does not use these indexes, but I'll looking
into using them for some simple cases...

[1] r13350 <http://trac.orbisgis.org/t/changeset/13350> ; task #539
<http://trac.orbisgis.org/t/ticket/539>

--
Antoine Gourlay
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