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+.\" ========================================================================
+.\"
+.IX Title "RRDGRAPH_LIBDBI 1"
+.TH RRDGRAPH_LIBDBI 1 "2009-06-09" "1.3.999" "rrdtool"
+.\" For nroff, turn off justification. Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH "NAME"
+rrdgraph_libdbi \- fetching data for graphing in rrdtool graph via libdbi
+.SH "SYNOPSIS"
+.IX Header "SYNOPSIS"
+<rrdfile> = \fBsql//<libdbi driver>/<driver\-option\-name>=<driver\-option\-value>/...[/rrdminstepsize=<stepsize>][/rrdfillmissing=<fill missing n samples>]//<table>/<unixtimestamp column>/<data value column>[/derive]/<where clause 1>/.../<where clause n>\fR
+.SH "DESCRIPTION"
+.IX Header "DESCRIPTION"
+This pseudo-rrd-filename defines a sql datasource:
+.IP "\fBsql//\fR" 8
+.IX Item "sql//"
+.Vb 1
+\& magic cookie\-prefix for a libdbi type datasource
+.Ve
+.IP "\fB<libdbi driver>\fR" 8
+.IX Item "<libdbi driver>"
+.Vb 1
+\& which libdbi driver to use (e.g: mysql)
+.Ve
+.IP "\fB<driver\-option\-name>\fR=\fB<driver\-option\-value>\fR" 8
+.IX Item "<driver-option-name>=<driver-option-value>"
+.Vb 2
+\& defines the parameters that are required to connect to the database with the given libdbi driver
+\& (These drivers are libdbi dependent \- for details please look at the driver documentation of libdbi!)
+.Ve
+.IP "\fB/rrdminstepsize\fR=\fB<minimum step size>\fR" 8
+.IX Item "/rrdminstepsize=<minimum step size>"
+.Vb 1
+\& defines the minimum number of the step\-length used for graphing (default: 300 seconds)
+.Ve
+.IP "\fB/rrdfillmissing\fR=\fB<fill missing steps>\fR" 8
+.IX Item "/rrdfillmissing=<fill missing steps>"
+.Vb 1
+\& defines the number of steps to fill with the last value to avoid NaN boxes due to data\-insertation jitter (default: 0 steps)
+.Ve
+.IP "\fB<table>\fR" 8
+.IX Item "<table>"
+.Vb 1
+\& defines the table from which to fetch the resultset.
+\&
+\& If there is a need to fetch data from several tables, these tables can be defined by separating the tablenames with a "+"
+\&
+\& hex\-type\-encoding via %xx are translated to the actual value, use %% to use %
+.Ve
+.IP "\fB<[*]unixtimestamp column>\fR" 8
+.IX Item "<[*]unixtimestamp column>"
+.Vb 2
+\& defines the column of E<lt>tableE<gt> which contains the unix\-timestamp
+\& \- if this is a DATETIME field in the database, then prefix with leading \*(Aq*\*(Aq
+\&
+\& hex\-type\-encoding via %xx are translated to the actual value, use %% to use %
+.Ve
+.IP "\fB<data value column>\fR" 8
+.IX Item "<data value column>"
+.Vb 1
+\& defines the column of E<lt>tableE<gt> which contains the value column, which should be graphed
+\&
+\& hex\-type\-encoding via %xx are translated to the actual value, use %% to use %
+.Ve
+.IP "\fB/derive\fR" 8
+.IX Item "/derive"
+.Vb 1
+\& defines that the data value used should be the delta of the 2 consecutive values (to simulate COUNTER or DERIVE type datasources)
+.Ve
+.IP "\fB/<where clause(s)>\fR" 8
+.IX Item "/<where clause(s)>"
+.Vb 1
+\& defines one (ore more) where clauses that are joined with AND to filter the entries in the <lt>table<gt>
+\&
+\& hex\-type\-encoding via %xx are translated to the actual value, use %% to use %
+.Ve
+.PP
+the returned value column-names, which can be used as ds-names, are:
+.IP "\fBmin\fR, \fBavg\fR, \fBmax\fR, \fBcount\fR and \fBsigma\fR" 8
+.IX Item "min, avg, max, count and sigma"
+.Vb 3
+\& are returned to be used as ds\-names in your DS definition.
+\& The reason for using this is that if the consolidation function is used for min/avg and max, then the engine is used several times.
+\& And this results in the same SQL Statements used several times
+.Ve
+.SH "EXAMPLES"
+.IX Header "EXAMPLES"
+Here an example of a table in a MySQL database:
+.PP
+.Vb 5
+\& DB connect information
+\& dbhost=127.0.0.1
+\& user=rrd
+\& password=secret
+\& database=rrd
+\&
+\& here the table:
+\& CREATE TABLE RRDValue (
+\& RRDKeyID bigint(20) NOT NULL,
+\& UnixTimeStamp int(11) NOT NULL,
+\& value double default NOT NULL,
+\& PRIMARY KEY (RRDKeyID,UnixTimeStamp)
+\& );
+.Ve
+.PP
+and the RRDKeyID we want to graph for is: 1141942900757789274
+.PP
+The pseudo rrd-filename to access this is:
+\&\*(L"sql//mysql/host=127.0.0.1/dbname=rrd/username=rrd/password=secret//RRDValue/UnixTimeStamp/value/RRDKeyID=1141464142203608274\*(R"
+.PP
+To illustrate this here a command to create a graph that contains the actual values.
+.PP
+.Vb 10
+\& DS_BASE="sql//mysql/host=127.0.0.1/dbname=rrd/username=rrd/password=passwd//RRDValue/UnixTimeStamp/value/RRDKeyID=1141942900757789274"
+\& rrdtool graph test.png \-\-imgformat=PNG \-\-start=\-1day \-\-end=+3hours \-\-width=1000 \-\-height=600 \e
+\& "DEF:min=$DS_BASE:min:AVERAGE" \e
+\& "LINE1:min#FF0000:value" \e
+\& "DEF:avg=$DS_BASE:avg:AVERAGE" \e
+\& "LINE1:avg#00FF00:average" \e
+\& "DEF:max=$DS_BASE:max:AVERAGE" \e
+\& "LINE1:max#FF0000:max" \e
+\& "DEF:sigma=$DS_BASE:sigma:AVERAGE" \e
+\& "CDEF:upper=avg,4,sigma,*,+" \e
+\& "LINE1:upper#0000FF:+4 sigma" \e
+\& "CDEF:lower=avg,4,sigma,*,\-" \e
+\& "LINE1:lower#0000FF:\-4 sigma"
+.Ve
+.SH "NOTES"
+.IX Header "NOTES"
+* Naturally you can also use any other kind of driver that libdbi supports \- e.g postgres, ...
+.PP
+* From the way the datasource is joined, it should also be possible to do joins over different tables
+ (separate tables with \*(L",\*(R" in table and add in the \s-1WHERE\s0 Clauses the table equal joins.
+ This has not been tested!!!)
+.PP
+* It should also be relatively simple to add to the database using the same datasource string.
+ This has not been implemented...
+.PP
+* The aggregation functions are ignored and several data columns are used instead
+ to avoid querying the same \s-1SQL\s0 several times when minimum, average and maximum are needed for graphing...
+.PP
+* for \s-1DB\s0 efficiency you should think of having 2 tables, one containing historic values and the other containing the latest data.
+ This second table should be kept small to allow for the least ammount of blocking \s-1SQL\s0 statements.
+ Whith mysql you can even use myisam table-type for the first and InnoDB for the second.
+ This is especially interresting as with tables with +100M rows myisam is much smaller then InnoDB.
+.PP
+* To debug the \s-1SQL\s0 statements set the environment variable \s-1RRDDEBUGSQL\s0 and the actual \s-1SQL\s0 statements and the timing is printed to stderr.
+.SH "BUGS"
+.IX Header "BUGS"
+* at least on Linux please make sure that the libdbi driver is explicitly linked against libdbi.so.0
+ check via ldd /usr/lib/dbd/libmysql.so, that there is a line with libdbi.so.0.
+ otherwise at least the perl module RRDs will fail because the dynamic linker can not find some symbols from libdbi.so.
+ (this only happens when the libdbi driver is actually used the first time!)
+ This is \s-1KNOWN\s0 to be the case with \s-1RHEL4\s0 and \s-1FC4\s0 and \s-1FC5\s0! (But actually this is a bug with libdbi make files!)
+.PP
+* at least version 0.8.1 of libdbiexhibits a bug with \s-1BINARY\s0 fields
+ (shorttext,text,mediumtext,longtext and possibly also \s-1BINARY\s0 and \s-1BLOB\s0 fields),
+ that can result in coredumps of rrdtool.
+ The tool will tell you on stderr if this occures, so that you know what may be the reason.
+ If you are not experiencing these coredumps, then set the environment variable \s-1RRD_NO_LIBDBI_BUG_WARNING\s0,
+ and then the message will not get shown.
+.SH "AUTHOR"
+.IX Header "AUTHOR"
+Martin Sperl <rrdtool@martin.sperl.org>