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From JohnnyS <jtk...@gmail.com>
Subject SQL Query index type
Date Mon, 10 Aug 2015 10:15:34 GMT
Hi

I'm using Apache Ignite to query a large spatial database using a z-order
curve and I'm trying to improve the query performance. One way to do this is
to use a hash index for equal queries. The H2 documentation says
(http://www.h2database.com/html/grammar.html#create_index) that "Hash
indexes are meant for in-memory databases and memory tables (CREATE MEMORY
TABLE). For other tables, or if the index contains multiple columns, the
HASH keyword is ignored. Hash indexes can only test for equality, and do not
support range queries (similar to a hash table)."

Does the ignite indexing system support hash indices and is there a way to
force the index type?

On a somewhat related note, could you clarify the order parameter in the
QuerySqlField.Group. If I have several indexed fields in a group and set
different orders for the indices, how does this affect the query behaviour
and performance?

Thanks,
johnny




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