From ee27eec40cba8e9d5c749f444b6090a8ba11e792 Mon Sep 17 00:00:00 2001 From: Olivier Doucet Date: Wed, 9 Jan 2013 15:52:44 +0100 Subject: [PATCH] Updated rrdgraph_libdbi doc about MySQL performance issues --- doc/rrdgraph_libdbi.pod | 12 ++++++++++++ 1 file changed, 12 insertions(+) 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 -- 2.47.2