We have a number of database monitor items that are created through Discovery Rules. The Discovery rule has a macro value "

{#DBNAME}", which we can use in discovered item's parameters. If we try to use a generic macro value, the item becomes unsupported.

Example item prototype parameters:

case 1: (macro value specified on hostname)

DSN={$DSN}
sql=select numbackends from pg_stat_database where datname = '{#DBNAME}

'

-> fails

case 2: (generic macro value)

DSN=

{HOSTNAME}
sql=select numbackends from pg_stat_database where datname = '{#DBNAME}'

-> fails

case 3: (only use discovery macro value)

DSN={#DBNAME}
sql=select numbackends from pg_stat_database where datname = '{#DBNAME}'

-> works

log output:

9170:20131010:150649.247 In substitute_key_macros() data:'db.odbc.select.database_size[{#DBNAME}]'
9170:20131010:150649.247 In substitute_discovery_macros() data:'{#DBNAME}'
9170:20131010:150649.247 End of substitute_discovery_macros() data:'zabbix'
9170:20131010:150649.247 End of substitute_key_macros():SUCCEED data:'db.odbc.select.database_size[zabbix]'
9170:20131010:150649.247 In substitute_discovery_macros() data:'Database size for {#DBNAME}'
9170:20131010:150649.247 End of substitute_discovery_macros() data:'Database size for zabbix'
9170:20131010:150649.247 In substitute_discovery_macros() data:'DSN={HOSTNAME}

^M
sql=select pg_database_size('

{#DBNAME}

')'
9170:20131010:150649.247 End of substitute_discovery_macros() data:'DSN=

{HOSTNAME}^M
sql=select pg_database_size('zabbix')'
9170:20131010:150649.247 In substitute_key_macros() data:''
9170:20131010:150649.247 End of substitute_key_macros():FAIL data:''
9170:20131010:150649.250 query [txnlev:1] [begin;]
9170:20131010:150649.251 query [txnlev:1] [update items set params='DSN={HOSTNAME}

sql=select pg_database_size(''zabbix'')' where itemid=24003;
]

Similar issue in ZBX-4638 was solved (difference with this ticket is the use of discovery).