Class: QueryGuard::Analysis::MissingIndexRiskDetector

Inherits:
RiskDetector
  • Object
show all
Defined in:
lib/query_guard/analysis/risk_detectors.rb

Overview

Detects missing table alias patterns (likely missing indexes)

Constant Summary collapse

FULL_TABLE_SCAN_INDICATORS =

Patterns that often indicate missing indexes

[
  /\bWHERE\b.*\b(?:LIKE|ILIKE|REGEXP)\b/i,  # LIKE on non-indexed column
  /\bON\b.*\b(?:FUNCTION|CAST|COALESCE)\b/i  # Function in JOIN condition
].freeze

Instance Attribute Summary

Attributes inherited from RiskDetector

#name

Instance Method Summary collapse

Constructor Details

#initialize ⇒ MissingIndexRiskDetector

Returns a new instance of MissingIndexRiskDetector.



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# File 'lib/query_guard/analysis/risk_detectors.rb', line 69

def initialize
  super(:missing_index_risk)
end

Instance Method Details

#detect(query, config) ⇒ Object 



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# File 'lib/query_guard/analysis/risk_detectors.rb', line 73

def detect(query, config)
  risks = []
  sql = query.sql

  # Simple heuristic: LIKE without index hint
  if matches_pattern?(sql, FULL_TABLE_SCAN_INDICATORS[0])
    risks << {
      pattern: :like_without_index,
      risk_level: :high,
      message: "LIKE pattern matching often requires full table scan; consider full-text search or indexed prefix matching",
      metadata: {
        recommendation: "Index column(s) or use full-text search",
        impact: "Sequential scan on large tables"
      }
    }
  end

  # Function in JOIN condition
  if matches_pattern?(sql, FULL_TABLE_SCAN_INDICATORS[1])
    risks << {
      pattern: :function_in_join,
      risk_level: :high,
      message: "Functions in JOIN conditions prevent index usage, causing sequential scans",
      metadata: {
        recommendation: "Move function outside JOIN condition",
        impact: "Index cannot be used"
      }
    }
  end

  risks
end