From: MARK CALLAGHAN Date: August 3 2010 4:21pm Subject: Re: 64 table join limit List-Archive: http://lists.mysql.com/internals/38014 Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 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 sche= maless design with an attribute table (ala couchDb etc.) where you might ne= ed a self-join for every field in the logical table. =A0I noticed the decla= ration ulonglong table_map is still in both 5.1 and 5.4 vs. key_map which i= s Bitmap<64>. =A0I wonder if anyone has an opinion if this is a safe change= to make for table_map? > > > > > > > -- > MySQL Internals Mailing List > For list archives: http://lists.mysql.com/internals > To unsubscribe: =A0 =A0http://lists.mysql.com/internals?unsub=3Dmdcallag@= gmail.com > > --=20 Mark Callaghan mdcallag@stripped