09-11-2012
Ways to preserve a memory cache
The environment is Java/Windows. The program keeps near real-time state in memory cache, which is updated by multiple sources, size of the cache is roughly 500 MB, frequency of updates is ~ 20 per second. I am looking into different ways to keep current snapshot of the memory on the disk for a) planned program restarts and b) possibility of failover. Requirement for downtime is not more than 2 minutes.
So far two options are discussed: 1) write serialized objects into plain files and 2) use RDBMS (MS SQL Server)
Both have pros and cons: for (1) there is considerable effort to re-populate cache from disk, but it should be the fastest; for (2) the programmers plan to use ORM, such as MyBatis and they say it will cut programming effort, although we are adding vulnerabilities of frequently updated RDBMS and speed needs to be proved to be fast enough.
What would gurus do?
Please don't suggest Hybernate, TopLink etc... to use as cache repository.
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LEARN ABOUT MOJAVE
dbix::class::storage::dbi::oracle::wherejoins
DBIx::Class::Storage::DBI::Oracle::WhereJoins(3) User Contributed Perl Documentation DBIx::Class::Storage::DBI::Oracle::WhereJoins(3)
NAME
DBIx::Class::Storage::DBI::Oracle::WhereJoins - Oracle joins in WHERE syntax support (instead of ANSI).
PURPOSE
This module is used with Oracle < 9.0 due to lack of support for standard ANSI join syntax.
SYNOPSIS
DBIx::Class should automagically detect Oracle and use this module with no work from you.
DESCRIPTION
This class implements Oracle's WhereJoin support. Instead of:
SELECT x FROM y JOIN z ON y.id = z.id
It will write:
SELECT x FROM y, z WHERE y.id = z.id
It should properly support left joins, and right joins. Full outer joins are not possible due to the fact that Oracle requires the entire
query be written to union the results of a left and right join, and by the time this module is called to create the where query and table
definition part of the SQL query, it's already too late.
METHODS
See DBIx::Class::SQLMaker::OracleJoins for implementation details.
BUGS
Does not support full outer joins. Probably lots more.
SEE ALSO
DBIx::Class::SQLMaker
DBIx::Class::SQLMaker::OracleJoins
DBIx::Class::Storage::DBI::Oracle::Generic
DBIx::Class
AUTHOR
Justin Wheeler "<jwheeler@datademons.com>"
CONTRIBUTORS
David Jack Olrik "<djo@cpan.org>"
LICENSE
This module is licensed under the same terms as Perl itself.
perl v5.18.2 2013-07-12 DBIx::Class::Storage::DBI::Oracle::WhereJoins(3)