Class: ActiveRecord::Materialized::AggregateAnalysis

Inherits:
Object
  • Object
show all
Defined in:
lib/activerecord/materialized/aggregate_analysis.rb

Overview

Decides whether a view can be maintained by applying signed deltas (summary-delta IVM) instead of re-aggregating a partition's base rows. True only for a single-table GROUP BY without HAVING whose aggregates are all distributive (SUM/COUNT/COUNT(*)) and which carries a trustworthy row count so emptied partitions can be detected; everything else falls back to scoped recompute, which is always correct.

Defined Under Namespace

Classes: Column

Instance Method Summary collapse

Constructor Details

#initialize(relation) ⇒ AggregateAnalysis

Returns a new instance of AggregateAnalysis.



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# File 'lib/activerecord/materialized/aggregate_analysis.rb', line 19

def initialize(relation)
  @relation = relation
  @aggregate_columns = nil
end

Instance Method Details

#aggregate_columns ⇒ Object 



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# File 'lib/activerecord/materialized/aggregate_analysis.rb', line 24

def aggregate_columns
  @aggregate_columns ||= @relation.select_values.filter_map { |value| classify(value) }
end

#delta_maintainable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/activerecord/materialized/aggregate_analysis.rb', line 28

def delta_maintainable?
  single_table? && grouped? && !having? && distributive_aggregates? && aggregate_columns.any?(&:counts_rows)
end

#distributive_aggregates? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/activerecord/materialized/aggregate_analysis.rb', line 32

def distributive_aggregates?
  aggregate_columns.any? && aggregate_columns.all? { |column| distributive?(column) }
end

#row_count_column ⇒ Object 



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# File 'lib/activerecord/materialized/aggregate_analysis.rb', line 36

def row_count_column
  aggregate_columns.find(&:counts_rows)
end