Added an example script to prune the rawdata table

etc/sample_stacktach_prune.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+# Example script to prune the Stacktach RawData table
+
+# The following is one way you could keep your RawData table from growing
+# very large -- keep only the last N days worth of data, N being a number
+# convenient to your installation.
+
+# Full path to where you have deployed the Stacktach app
+PATH_TO_ST='/path/to/stacktach'
+
+# Let us say we want to keep only 90 days' worth of RawData.
+# 90 days = 90 * (24*60*60) seconds = 7776000 seconds.
+KEEP_RAWDATA_DAYS=90
+KEEP_RAWDATA_SECS=$((KEEP_RAWDATA_DAYS*24*60*60))
+
+# Source the stacktach_config.sh script to populate the 
+# STACKTACH_DB_* variables among other things, and do the deed.
+cd ${PATH_TO_ST} && \
+. ${PATH_TO_ST}/etc/stacktach_config.sh && \
+python manage.py dbshell <<EOF \
+     > /tmp/stacktach_prune.stdout \
+    2> /tmp/stacktach_prune.stderr
+
+DELETE FROM stacktach_rawdata
+WHERE stacktach_rawdata.when < (UNIX_TIMESTAMP(NOW())-${KEEP_RAWDATA_SECS});
+
+EOF