Class: PgCanary::Rules::RegexWithoutTrgm

Inherits:
Base
  • Object
show all
Includes:
IndexPredicates
Defined in:
lib/pg_canary/rules/definitions/regex_without_trgm.rb

Overview

Regular-expression search (~, ~*, SIMILAR TO) cannot use a plain btree index; only a pg_trgm GIN/GiST index can serve it. The regex variant of leading_wildcard_like.

Constant Summary collapse

REGEX_OPS = 
%w[~ ~* !~ !~*].freeze

Constants included from IndexPredicates

IndexPredicates::TRGM_ACCESS_METHODS

Instance Method Summary collapse

Methods inherited from Base

all, check, default_enabled, enabled?, #initialize, option, options, rule_name

Constructor Details

This class inherits a constructor from PgCanary::Rules::Base

Instance Method Details

#check ⇒ Object 



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# File 'lib/pg_canary/rules/definitions/regex_without_trgm.rb', line 17

def check
  detections = []
  each_scope do |scope|
    next unless scope.where_clause

    scope.where_clause.walk_scope do |node|
      next unless node.is_a?(PgQuery::A_Expr)

      operator = display_operator(node)
      next unless operator

      column_ref = node.lexpr&.strip_casts
      next unless column_ref.is_a?(PgQuery::ColumnRef)

      table, column = scope.resolve(column_ref)
      next unless table && column
      next unless applicable_table?(table)
      next if trgm_index?(table, column)

      detections << detection(
        table: table,
        columns: column,
        message: "Regular-expression search (#{operator}) on #{table}.#{column} cannot use " \
                 "a btree index and will scan every row in production.",
        suggestion: <<~SUGGESTION.chomp
          Consider the pg_trgm extension with a GIN index:
            CREATE EXTENSION IF NOT EXISTS pg_trgm;
            CREATE INDEX index_#{table}_on_#{column}_trgm ON #{table} USING gin (#{column} gin_trgm_ops);
        SUGGESTION
      )
    end
  end
  detections
end