erland;230298 Wrote: > I've setup a number of different indexes, but I expect that with a > 4,500,000 row table index can make some things fast but a five time > join on this table, it is probably impossible to get 1-2 second > response time independent which index that are used. But if someone are > good at setting up database index with MySQL, I'm really interesting in > help regarding this.
I was reading from SQL Unleashed last night and on the topic of index versus full table scans it mentions the following tradeoffs: - if you need to retrieve only one or a few rows and they are identifiable through an index, then an index lookup is likely to be the most efficient approach - if you need to retrieve a sizeable portion of a table's rows, a full table scan is more efficient The "grey zone" is defined as between 5 - 20% of a table's rows to be retrieved - below 5% an index will likely perform better and above 20% the full table scan will perform better. The suggestion is made that one should test queries in the "grey zone" to ascertain which performs better having regard to the tables in question. -- egd Thecus N5200PRO >> Transporter >> ATC SCA2 >> ATC SCM100SLAT ------------------------------------------------------------------------ egd's Profile: http://forums.slimdevices.com/member.php?userid=3425 View this thread: http://forums.slimdevices.com/showthread.php?t=38714 _______________________________________________ plugins mailing list plugins@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/plugins
