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From:MARK CALLAGHAN Date:August 3 2010 4:21pm
Subject:Re: 64 table join limit
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Is there a better way to support this? Db servers I care about have
suffered greatly from such support for schema-less apps. A row per
attribute using the columns (attribute name, attribute value) might be
good when these attributes are to be indexed. Otherwise, this can be a
huge drain on performance.

On Tue, Aug 3, 2010 at 8:41 AM, Dan Meany <dan_meany@stripped> wrote:
> The 64 table limit on joins was discussed with a proposed solution based on the
> change to key_map in the thread 16713 some time ago:
>
> http://lists.mysql.com/internals/16713
>
> This has become much more of a constraint when implementing a partly schemaless
> design with an attribute table (ala couchDb etc.) where you might need a self-join for
> every field in the logical table.  I noticed the declaration ulonglong table_map is
> still in both 5.1 and 5.4 vs. key_map which is Bitmap<64>.  I wonder if anyone
> has an opinion if this is a safe change to make for table_map?
>
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-- 
Mark Callaghan
mdcallag@stripped
Thread
64 table join limitDan Meany3 Aug
  • Re: 64 table join limitMARK CALLAGHAN3 Aug
    • Re: 64 table join limitDan Meany3 Aug