SYNOPSIS
A simplified object to manage a collection of information related to streaming data from
a database. at least with MYSQL, the perl driver does odd caching so to stream one
needs to create a new database connection in order to stream
DESCRIPTION
LICENSE
* Software License Agreement (BSD License)
* MappedQueryDB [MQdb] toolkit
* copyright (c) 2006-2009 Jessica Severin
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
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* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Jessica Severin nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
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APPENDIX
The rest of the documentation details each of the object methods. Internal methods are labeled.
set_stream_useresult_behaviour
Description : sets a global behaviour for all DBStreams.
setting use_result to "on" will leave the results on the database and
will keep the database connection open durring streaming.
Both methods have similar speed performance, but keeping the results
on the database server means the client uses essentially no memory.
The risk of turning this on is that the the database connection remains open
and there is risk of it timing out if processing takes a long time to stream all data.
When turned off, the entire result set is transfered in bulk to the driver (DBD::mysql)
and streaming happens from the underlying driver code and the perl code layer.
Default is "off" since this is safer but one risks needing lots of memory on the client.
Parameter[1] : 1 or "y" or "on" turns the use_result on and keeps the database connection open
Returntype : none
Exceptions : none
Example : MQdb::DBStream->set_stream_useresult_behaviour(1);
next_in_stream
Description: gets the next object in the stream. If the stream is empty it return undef.
Returntype : instance of the defined DBStream::stream_class, or undef
Exceptions : none
Example :
my $stream = WorldKit::Person->stream_all_by_country_region($db, "USA", "wisconsin");
while(my $person = $stream->next_in_stream) {
#do something
}
as_array
Description: instantiates all remaining instances in the stream and returns them as an array
Returntype : reference to array of instances of the defined class of this stream
Exceptions : none
Example :
my $stream = WorldKit::Person->stream_all_by_country_region($db, "USA", "wisconsin");
my $all_people = $stream->as_array; #because I have a large memory machine and need them all in memory
foreach my $person (@$all_people) {
#do something
}
stream_database
Description: this is an internal system method.
Needs to have two database connections open, one for the active
stream handle, and one for lazy-loading additional data on the returned
objects. This is used to set the database which is the one streaming objects
Arg (1) : $database (MQdb::Database) for setting
Returntype : MQdb::Database
Exceptions : none
Callers : MQdb::MappedQuery
stream_class
Description: this is an internal system method.
Set/get the class used for creation of objects on this stream.
The class must be a subclass of MQdb::MappedQuery
Arg (1) : $class (must be subclass of MQdb::MappedQuery) for setting
Returntype : a class which is a subclass of MQdb::MappedQuery
Exceptions : none
Callers : MQdb::MappedQuery
prepare
Description: this is an internal system method. It is used to set the SQL query used
to stream objects out of a database. Must be have stream_class() set
to a subclass of MappedQuery which implements the mapRow() method.
Returntype : $self
Exceptions : none
Callers : MQdb::MappedQuery
