From: Olivier Doucet Date: Wed, 9 Jan 2013 14:52:44 +0000 (+0100) Subject: Updated rrdgraph_libdbi doc about MySQL performance issues X-Git-Tag: v1.5.0-rc1~199^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F363%2Fhead;p=thirdparty%2Frrdtool-1.x.git Updated rrdgraph_libdbi doc about MySQL performance issues --- diff --git a/doc/rrdgraph_libdbi.pod b/doc/rrdgraph_libdbi.pod index 1e4aa4db..b8575601 100644 --- a/doc/rrdgraph_libdbi.pod +++ b/doc/rrdgraph_libdbi.pod @@ -138,6 +138,18 @@ To illustrate this here a command to create a graph that contains the actual val * To debug the SQL statements set the environment variable RRDDEBUGSQL and the actual SQL statements and the timing is printed to stderr. + + +=head1 Performance issues with MySQL backend + +LibDBI has a big performance issue when you retrieve data from a MySQL server. Performance impact is exponentially based on the number of +values you retrieve from the database. +For example, it would take more than 2 seconds to graph 5DS on 150 hours of data with a precision of 5 minutes +(against 100ms when data comes from a RRD file). This bug has been fixed on latest version of LibDBI (not release yet). +At that time, you would need to compile libdbi and libdbi-drivers from CVS repository to fix it. +You can find more informations on this libdbi-users mailing list thread : http://sourceforge.net/mailarchive/message.php?msg_id=30320894 + + =head1 BUGS * at least on Linux please make sure that the libdbi driver is explicitly linked against libdbi.so.0