03-25-2013
If you can segregate high churn and query from low churn and query (work in progress versus quiescent history), RAID alone is fine for history, but mirror is better for both high churn and high query.
For instance, RAID with 5 drives 1-5 is striped so drive 5 block zero is parity for superblock 0, and drive 5 block 1 starts superblock1. Every write writes all 5 drives and every read can only be had from one device, but sequential reading is striped 5 ways. Writing is striped 4 ways since parity takes the 5th drive.
In practice, SAN mirrors are often raid at a lower level, so there can be a hidden cost, since you cannot reclaim the raid %.
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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 v5.16.2 2012-08-16 DBIx::Class::Storage::DBI::Oracle::WhereJoins(3)