Cypher Pattern Library
Write Patterns (Ingestion)
Safe MERGE — always idempotent
MERGE (p:Program {program_id: $program_id})
ON CREATE SET p.created_at = datetime()
ON MATCH SET p.updated_at = datetime()
SET p.source_path = $source_path,
p.line_count = $line_count
Create relationship safely
MATCH (a:Program {program_id: $caller})
MATCH (b:Program {program_id: $callee})
MERGE (a)-[r:CALLS]->(b)
SET r.using_params = $params
Bulk paragraph creation (use UNWIND for arrays)
UNWIND $paragraphs AS para
MERGE (p:Paragraph {fqn: $program_id + '.' + para.name})
SET p.name = para.name,
p.line_start = para.line_start,
p.line_end = para.line_end
MERGE (prog:Program {program_id: $program_id})
MERGE (prog)-[:CONTAINS]->(p)
Read Patterns (Analysis)
Full dependency tree (bounded depth)
MATCH path = (start:Program {program_id: $name})-[:CALLS*1..10]->(end:Program)
RETURN path, length(path) AS depth
ORDER BY depth
Reverse: everything that calls this program
MATCH path = (caller:Program)-[:CALLS*1..10]->(target:Program {program_id: $name})
RETURN caller.program_id, length(path) AS hops
ORDER BY hops
Copybook blast radius
MATCH (cb:Copybook {name: $copybook_name})<-[:INCLUDES]-(p:Program)
OPTIONAL MATCH (p)<-[:CALLS*1..5]-(upstream:Program)
RETURN DISTINCT p.program_id AS direct_user,
collect(DISTINCT upstream.program_id) AS transitive_callers
Find circular dependencies
MATCH (a:Program)-[:CALLS*2..]->(a)
RETURN a.program_id AS circular_program
Programs with no inbound calls (leaf programs — safe to migrate first)
MATCH (p:Program)
WHERE NOT ()-[:CALLS]->(p)
RETURN p.program_id, p.migration_score, p.migration_category
ORDER BY p.migration_score ASC
Fan-in / Fan-out coupling metrics
MATCH (p:Program)
OPTIONAL MATCH (p)-[:CALLS]->(callee)
OPTIONAL MATCH (caller)-[:CALLS]->(p)
RETURN p.program_id,
count(DISTINCT callee) AS fan_out,
count(DISTINCT caller) AS fan_in,
count(DISTINCT callee) + count(DISTINCT caller) AS total_coupling
ORDER BY total_coupling DESC
LIMIT 20
Data items shared across most programs (high-risk copybooks)
MATCH (cb:Copybook)<-[:INCLUDES]-(p:Program)
RETURN cb.name, count(p) AS used_by_programs
ORDER BY used_by_programs DESC
LIMIT 10
Aggregation Patterns (Reporting)
Node count by label
MATCH (n) RETURN labels(n)[0] AS label, count(n) AS count ORDER BY count DESC
Relationship count by type
MATCH ()-[r]->() RETURN type(r) AS rel, count(r) AS count ORDER BY count DESC
Migration readiness dashboard
MATCH (p:Program)
RETURN p.migration_category AS category,
count(p) AS programs,
avg(p.migration_score) AS avg_score,
sum(p.line_count) AS total_lines
ORDER BY avg_score ASC
For ingestion-specific patterns: read WRITE-PATTERNS.md
For analysis query templates: read QUERY-PATTERNS.md
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