NAME
DBIx::Class::Snowflake::Manual - Manual for setting up DBIx::Class::Snowflake with Snowflake schemas.
SYNOPSIS
package My::Snowflake::DimDate;
use base 'DBIx::Class';
__PACKAGE__->table('DimDate');
# makes the class a Dimension of a Snowflake/Star
__PACKAGE__->load_components("Snowflake::Dimension");
# NECESSARY to use this resultset or something based off of it
__PACKAGE__->resultset_class('DBIx::Class::Snowflake::ResultSet::Dimension');
# Allows you to tell Snowflake to not pay attention to the ID column
__PACKAGE__->ignore_columns('date_id']);
package My::SnowFlake::FactSale;
use base 'DBIx::Class';
__PACKAGE__->table('FactSale');
# makes the class a Fact of a Snowflake/Star
__PACKAGE__->load_components("Snowflake::Fact");
# NECESSARY to use this resultset or something based off of it
__PACKAGE__->resultset_class('DBIx::Class::Snowflake::ResultSet::Fact');
# Allows you to tell Snowflake to not pay attention to the ID column
# or other unnecessary columns
__PACKAGE__->ignore_columns(['sale_id', 'some_other_bad_column']);
# meanwhile elsewhere in your code...
my $possible_attributes = $schema->resultset('FactSale')->attributes();
my $wanted_metrics = some_function_to_get_metrics($possible_attributes);
my $wanted_filters = some_function_to_setup_filters($possible_attributes);
my $report_rs = $schema->resultset('FactSale')->generate_report(
{
'filters' => $wanted_filters,
'metrics' => $wanted_metrics
}
);
# do something with your report...DESCRIPTION
A full description of the module and its features. May include numerous subsections (i.e. =head2, =head3, etc.)
SUBROUTINES/METHODS
NOTE All subroutines that can be called on a row can be called on a resultset and vice versa, they will act the exact same. That is, if you setup the schema like it says to above, if not then your mileage will vary.
subs for facts and dimensions
ignore_columns
ignore_columns takes 1 parameter. The parameter can be a string, a hashref, an arrayref, a stringref, or a coderef. It accepts the parameter and ignores those columns for that class not for any dimensions fo that class.
If the ignore_columns subroutine is called on an instance it is only valid for that instance, if it is called on the package then it is valid for all instances.
NOTE: The columns are only ignored for that class, you CANNOT set all the columns in all of the dimensions to be ignored in the fact and expect that to work.
How it handles thing:
- string
-
It assumes it is the name of a column to ignore.
- stringref
-
It treats the string referred to like a string.
- hashref
-
It assumes it is a hash formatted like: { 'ignored_column_A' => 1, 'ignored_column_B' => 1 } The value doesn't matter, if the column is a key in this hash it is ignored.
- arrayref
-
It assumes each entry in the array is a column name to be ignored
- coderef
-
It executes the code referenced and then passes the values into itself so that the results of the code are treated as a hashref, etc. would be treated.
- undef
-
It resets the columns it is remembering to ignore for that class or instance.
attrs
See attributes.
attributes
Calling this on a dimension or a fact will recursively search all of the dimensions of that class and return a list of all not ignored attributes and their types in the following format:
[
{ 'name' => 'dim_rel_accessorA.col_A', 'type' => 'integer' },
{ 'name' => 'dim_rel_accessorA.col_B', 'type' => 'text' },
{ 'name' => 'dim_rel_accessorB.col_1', 'type' => 'date' },
{ 'name' => 'dim_rel_accessorC.count', 'type' => 'integer' },
]subs for just facts
generate_report
generate_report generates a report given some set of metrics and filters. This works in the DBIC standard fashion in that when called in an array context it returns an array of results and when called in a scalar fashion it returns a ResultSet object.
This takes one parameter which is a hashref with the following format:
{
'filters' =>
{
'dimAuthor.last_name' => 'Norman',
'dimRegion.name' => 'Missouri',
'dimSaleDate.day_of_week' => 3
},
'metric' =>
{
'dimBook.EAN_code' => 1,
'dimCity.name' => 1,
'dimCategory.name' => 1
}
}For the filters hash the values should be the value you are filtering on, for the metrics hash the value is ignored, it is only formatted like that for consistency.
The easiest way to use generate_report is in conjunction with attributes(). The names provided by attributes are the same names generate_report expects.
The resultset returned will have columns for each of the metrics requested regardless of where they are actually located in the schema, so for exampe.
$rs = $schema->resultset('FactSales')->generate_report($data_above)$rs will have a column dimBook.EAN_code, but it won't have an accessor to access it do this:
$rs->get_column('dimBook.EAN_code');Then you can treat it like a normal column by getting it's values, max, etc.
DIAGNOSTICS
Can't locate object method "generate_report" via package "MySchema::FactB" at ... - You forgot to load the Snowflake::Fact component for fact table FactB.
Can't locate object method "attributes" via package "DBIx::Class::ResultSet" at ... - You forgot to set the resultset_class to DBIx::Class::Snowflake::ResultSet::Dimension or DBIx::Class::Snowflake::ResultSet::Fact for one of the facts or dimensions in your table.
Can't locate object method "_resolve_metrics" via package "MySchema::DimExample" at ... - You forgot to load the Snowflake::Dimension component for the dimension table DimExample.
Unable to resolve dimension 'some_attr', does not exist in snowflake. at... - You've passed in an attribute inside the filters hash into generate_report that doesn't exist, after it searched all of your dimensions it gave up.
Unable to resolve dimension 'some_attr', does not exist in snowflake. at... - You've passed in an attribute inside your metric hash into generate_report that doesn't exist, after it searched all of your dimensions it gave up.
Unable to determine what columns to ignore, I don't know what to do with a 'something'. - You've passed in something to ignore_columns that isn't an acceptable value. Or, possibly, you passed in a coderef that generated a value that wasn't acceptable.
DEPENDENCIES
This Module requires DBIx::Class. This module should probably be used in only star and snowflake schemas, but if you find another use for this then please let me know via email.
INCOMPATIBILITIES
A list of any modules that this module cannot be used in conjunction with. This may be due to name conflicts in the interface, or competition for system or program resources, or due to internal limitations of Perl (for example, many modules that use source code filters are mutually incompatible).
TODO
Base name of attribute on name of column and name of table 'table.column' =head1 TODO
Base name of attribute on name of column and name of table 'table.column' so that all attributes are guaranteed to have a unique name.
Modify generate_report so it generates a smaller set of JOINs
Modify the filter conversion code to be more efficient.
so that all attributes are guaranteed to have a unique name.
Modify generate_report so it generates a smaller set of JOINs
Modify the filter conversion code to be more efficient.
BUGS AND LIMITATIONS
There is one known limitation. The module understands an attribute as the name of the relationship that got it there and the name of the column. So, for example, if you had two classes, DimDate and FactSale, and FactSale had a relationship with DimDate called date_id and DimDate had an attribute called day_of_week this module would assume that date_id.day_of_week was unique. If there is some other dimension that would translate to date_id.day_of_week there is no guarantee as to which one would be picked.
The generate_report function could be made to be more efficient.
Please report other problems to Matt Follett<cpan(AT_GOES_HERE)mfollett.com> Patches are welcome.