[mapserver-users] Mapcache time dimension default value; and 'tearing down pooled connection' message

[Trygve Aspenes]

Hi there!

Slowly I'm getting mapserver/mapcache up running and looks now how to 
improve things.

First: When I load a mapcache tileset with time dimension from a pg db 
the oldest image is displayed in my client. Is it possible to somehow 
get the newest image as default?
My tileset dimension look something like this:

             <dimension type="postgresql" name="time" default="d1" 
time="true" unit="ISO8601">
                 <connection>
                     host=mapserver-db user=$PGSQ_USERNAME 
password=$PGSQ_PASSWORD dbname=mapserver port=5432
                 </connection>
                 <list_query>SELECT to_char(time, 
'YYYY-MM-DD"T"HH24:MI:SS"Z"') FROM products where product_name='<some 
product>' order by Id</list_query>
                 <validate_query>
                     SELECT to_char(time,'YYYY-MM-DD"T"HH24:MI:SS"Z"') 
FROM products
                     WHERE time >= to_timestamp(:start_timestamp)
                     AND time <= to_timestamp(:end_timestamp)
                     AND product_name='<some product>'
                     ORDER BY time DESC
                 </validate_query>
             </dimension>

I saw the `d1` default value in the documentation, but don't understand 
of that is a dummy or an actual selector. I have grepped around the 
source code, but could not see anything obvious.

Second: My client updates/fetch the getCapabilities of my mapcache 
server every minute. Each time this is fetched the mapcache log is 
filled with messages like:

mod_mapcache.c(164): [client ] tearing down pooled connection (dim_<some 
product>_time) to make room, referer: <my client>

I dont understand why these connections is teared down every time 
getCapabilites is requested.

I have looked in the documentation, but could not see how to control 
this. But in the mapcache.xml.sample the connection pool config is 
described. But adding this to my mapcache config does not remove these 
tear downs.

     <connection_pool>
         <max_connections>2000</max_connections>
         <time_to_live_us>120000000</time_to_live_us>
     </connection_pool>

Any suggestions why this connection tear down is happening and if there 
is something to do about it. It slows down the getCapabilities request a 
bit, but if I add to many tileset I guess this will even further slow 
down.

Thanks

Trygve Aspenes