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Re: 64 table join limit


Hi Dan

On 05/08/2010, at 12:28 AM, Dan Meany wrote:
Hi, I was wondering if anyone here had any opinions about this proposed fix for the 64 table join limit (originally by Sergei)


With the increased use of schemaless and hybrid, partly schemaless application designs, this would be a big enhancement. In my own application, being able to make minor, typed, virtual column additions for different SAAS clients in virtual tables at runtime without changing the physical schema or regenerating application binding layers is pretty priceless. But currently we are limited to 64 virtual columns by this mySQL join limit.

While I'm not opposed to the limit being raised if this is possible within a reasonable development effort, I tend to find that a need for this typically arises from:
 - query generation
 - views

And it comes down to query patterns requiring a lot of joins or self- joins to construct something in defiance of the schema, or in defiance of the relational model. - if it's the schema, then the schema should be modified to optimally work with these queries, rather than be focused on the data that's in them. basic guideline. - if you really want to be schemaless, don't use an RDBMS. RDBMS are structured, for a reason. It helps in a multitude of ways. Sometimes for whatever reason you can decide that structure is not what you need, but then using an RDBMS (apart from the familiar convenient interface) makes no sense. - if you're battling the relational model but do want its structure rules, sometimes the OQGRAPH engine can be of help since it allows you to deal with hierarchical and network/graph type structures in a relational way. This cuts out a lot of joins and query complexity. MariaDB 5.2 has the OQGRAPH engine integrated.

If you'd like assistance with the schema, or utilising OQGRAPH, we'd be happy to help.

Arjen Lentz, Exec.Director @ Open Query (http://openquery.com)
Exceptional Services for MySQL at a fixed budget.

Follow our blog at http://openquery.com/blog/
OurDelta: packages for MySQL and MariaDB @ http://ourdelta.org

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