Database trigger/monitor without polling
lazarus / 16-Databases

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LittleBritaly · 2014-03-17 08:08

I'm looking for a way to monitor a mysql table for changes without
polling every second or so.

At the moment I'm using Lnet to send a message to a (local network)
server, which then polls the database and prints off an order (it's
the only machine on the local network with a printer).

The database is not stored locally (it's at our web url) and I'm
unhappy with relying on a communication connection between the two
machines on the  local network.

I'd much rather have the 'print server' be able to monitor a table /
receive a push notification, is there a cleaner way to do this with
Lazarus (even changing the database engine if required).

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BigChimp · 2014-03-17 08:21

Not a Mysql guy... perhaps MySQL provides some kind of trigger
mechanism which can call an external executable/connect to a port and
send data/etc.

Both Firebird and PostgreSQL support events and Lazarus/FPC's sqldb
(as well as Zeos, I think) offer support for that mechanism:

http://wiki.lazarus.freepascal.org/Firebird_in_action#Monitoring_Event
s

http://wiki.lazarus.freepascal.org/postgresql#Event_monitoring