postinst is in pinba-engine-mysql-5.7 1.1.0-1ubuntu1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | #!/bin/sh
set -e
. /usr/share/debconf/confmodule
if [ -f /usr/share/dbconfig-common/dpkg/postinst.mysql ]; then
        dbc_dbname="pinba"
	. /usr/share/dbconfig-common/dpkg/postinst.mysql
	dbc_go pinba-engine-mysql-5.7 $@
        case postinst."$1" in
            prerm.remove)
                if [ "$dbc_purge" = "true" ]; then
                    dbc_logpart "uninstalling pinba plugin... "
                    rem=`dbc_mktemp`
                    echo "UNINSTALL PLUGIN pinba;" > $rem
                    _dbc_nodb="yes" $dbc_sqlfile_cmd $rem || dbc_remove_error "uninstalling pinba plugin"
                    rm -f $rem
                    dbc_logline "done"
                fi
                ;;
        esac
fi
exit 0
 |