feat: auto-rebalance, Cypher-like graph queries, tutorial examples — 232 tests

Cluster Auto-Rebalance:
- ClusterMembership with onNodeJoin/onNodeLeave/onNodeFail
- Automatic shard reassignment on node failure
- Rebalance triggers on member changes

Cypher-like Graph Queries:
- MATCH/CREATE/MERGE/DELETE query parser
- Full pattern parsing: nodes with labels/properties, edges with labels
- WHERE, RETURN, ORDER BY, LIMIT clauses
- executeCypher for basic graph matching

Tutorial:
- 8 comprehensive examples: KV store, B-Tree, vector search, graph, FTS, MVCC, BaraQL parsing, community detection
- Runnable demo with all major engines

10 new tests (232 total, all passing)
This commit is contained in:
2026-05-06 02:05:20 +03:00
parent d80ec4e449
commit a7e66cb661
4 changed files with 579 additions and 1 deletions
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## BaraDB Examples — getting started tutorials
import ../src/barabadb/storage/lsm
import ../src/barabadb/storage/btree
import ../src/barabadb/vector/engine
import ../src/barabadb/graph/engine
import ../src/barabadb/graph/community
import ../src/barabadb/fts/engine
import ../src/barabadb/core/mvcc
import ../src/barabadb/query/lexer
import ../src/barabadb/query/parser
# Example 1: Basic Key-Value Store
proc exampleKeyValue() =
echo "=== Example 1: Key-Value Store ==="
var db = newLSMTree("./tutorial_kv")
# Put data
db.put("user:1", cast[seq[byte]]("Alice,30,Engineer"))
db.put("user:2", cast[seq[byte]]("Bob,25,Designer"))
db.put("user:3", cast[seq[byte]]("Charlie,35,Manager"))
# Get data
let (found, value) = db.get("user:1")
if found:
echo " user:1 = ", cast[string](value)
# Contains check
echo " user:1 exists: ", db.contains("user:1")
echo " user:99 exists: ", db.contains("user:99")
# Delete
db.delete("user:3")
echo " user:3 deleted: ", db.contains("user:3")
db.close()
# Example 2: B-Tree Range Queries
proc exampleBTree() =
echo "=== Example 2: B-Tree Range Queries ==="
var btree = newBTreeIndex[string, string]()
for i in 0..<100:
btree.insert("key_" & $i, "value_" & $i)
# Point query
let vals = btree.get("key_42")
echo " Point query key_42: ", vals
# Range scan
let range = btree.scan("key_10", "key_20")
echo " Range scan key_10..key_20: ", range.len, " results"
echo " First: ", range[0][0], " = ", range[0][1]
echo " Last: ", range[^1][0], " = ", range[^1][1]
# Example 3: Vector Similarity Search
proc exampleVectorSearch() =
echo "=== Example 3: Vector Similarity Search ==="
var idx = newHNSWIndex(dimensions = 3)
# Insert vectors with metadata
idx.insert(1, @[1.0'f32, 0.0'f32, 0.0'f32], {"type": "red"}.toTable)
idx.insert(2, @[0.0'f32, 1.0'f32, 0.0'f32], {"type": "green"}.toTable)
idx.insert(3, @[0.0'f32, 0.0'f32, 1.0'f32], {"type": "blue"}.toTable)
idx.insert(4, @[0.9'f32, 0.1'f32, 0.0'f32], {"type": "red"}.toTable)
# Search similar vectors
let query = @[1.0'f32, 0.0'f32, 0.0'f32]
let results = idx.search(query, k = 3)
echo " Search results for [1.0, 0.0, 0.0]:"
for (id, dist) in results:
echo " ID: ", id, " distance: ", dist
# Example 4: Graph Traversal
proc exampleGraph() =
echo "=== Example 4: Graph Traversal ==="
var g = newGraph()
# Create nodes
let alice = g.addNode("Person", {"name": "Alice", "age": "30"}.toTable)
let bob = g.addNode("Person", {"name": "Bob", "age": "25"}.toTable)
let charlie = g.addNode("Person", {"name": "Charlie", "age": "35"}.toTable)
let diana = g.addNode("Person", {"name": "Diana", "age": "28"}.toTable)
# Create edges
discard g.addEdge(alice, bob, "KNOWS")
discard g.addEdge(bob, charlie, "KNOWS")
discard g.addEdge(alice, diana, "KNOWS")
# BFS traversal
let bfs = g.bfs(alice)
echo " BFS from Alice: ", bfs.len, " nodes"
# Shortest path
let path = g.shortestPath(alice, charlie)
echo " Shortest path Alice→Charlie: ", path.len, " hops"
# PageRank
let ranks = g.pageRank()
echo " PageRank top node: ", ranks.entries().sorted(
proc(a, b: (NodeId, float64)): int = cmp(b[1], a[1]))[0]
# Example 5: Full-Text Search
proc exampleFTS() =
echo "=== Example 5: Full-Text Search ==="
var idx = newInvertedIndex()
# Add documents
idx.addDocument(1, "Nim is a statically typed compiled language with Python-like syntax")
idx.addDocument(2, "Python is an interpreted language popular for data science")
idx.addDocument(3, "Rust is a systems programming language with memory safety")
idx.addDocument(4, "JavaScript runs in browsers and on servers via Node.js")
# BM25 search
echo " BM25 search: 'programming language':"
for result in idx.search("programming language", limit = 3):
echo " Doc ", result.docId, " score: ", result.score
# TF-IDF search
echo " TF-IDF search: 'compiled language':"
for result in idx.searchTfidf("compiled language", limit = 3):
echo " Doc ", result.docId, " score: ", result.score
# Fuzzy search
echo " Fuzzy search: 'propgramming' (typo):"
for result in idx.fuzzySearch("propgramming", maxDistance = 2, limit = 3):
echo " Doc ", result.docId, " score: ", result.score
# Example 6: Transactions (MVCC)
proc exampleTransactions() =
echo "=== Example 6: Transactions ==="
var tm = newTxnManager()
# Transaction 1: write
let txn1 = tm.beginTxn()
discard tm.write(txn1, "balance:alice", cast[seq[byte]]("100"))
discard tm.write(txn1, "balance:bob", cast[seq[byte]]("200"))
discard tm.commit(txn1)
# Transaction 2: snapshot isolation
let txn2 = tm.beginTxn()
# Can't see concurrent writes
let (found, val) = tm.read(txn2, "balance:alice")
echo " Alice balance (txn2 before commit): ", if found: cast[string](val) else: "nil"
# Transaction 3: concurrent write
let txn3 = tm.beginTxn()
discard tm.write(txn3, "balance:alice", cast[seq[byte]]("150"))
discard tm.commit(txn3)
# txn2 still sees old value (snapshot)
let (found2, val2) = tm.read(txn2, "balance:alice")
echo " Alice balance (txn2 after txn3 commit): ", if found2: cast[string](val2) else: "nil"
discard tm.commit(txn2)
# New transaction sees latest
let txn4 = tm.beginTxn()
let (found3, val3) = tm.read(txn4, "balance:alice")
echo " Alice balance (new txn): ", if found3: cast[string](val3) else: "nil"
discard tm.commit(txn4)
# Example 7: BaraQL Query Parsing
proc exampleBaraQL() =
echo "=== Example 7: BaraQL Query Parsing ==="
let queries = [
"SELECT name, age FROM users WHERE age > 18 ORDER BY name LIMIT 10",
"INSERT users { name := 'Alice', age := 30 }",
"UPDATE users SET name = 'Bob' WHERE id = 1",
"DELETE FROM users WHERE id = 99",
"SELECT dept, count(*), avg(salary) FROM employees GROUP BY dept HAVING count(*) > 5",
"SELECT u.name, o.total FROM users u LEFT JOIN orders o ON u.id = o.user_id",
"WITH recent AS (SELECT * FROM orders WHERE date > '2025-01-01') SELECT * FROM recent",
]
for query in queries:
try:
let tokens = tokenize(query)
let ast = parse(tokens)
echo "", query[0..<min(query.len, 60)], "..."
except Exception as e:
echo "", query[0..<min(query.len, 40)], "... : ", e.msg
# Example 8: Community Detection
proc exampleCommunity() =
echo "=== Example 8: Community Detection ==="
var g = newGraph()
# Create two communities with dense internal connections
var nodes: seq[NodeId] = @[]
for i in 0..<10:
nodes.add(g.addNode("User_$1", {"id": $i}.toTable))
# Community 1: fully connected
for i in 0..4:
for j in i+1..4:
discard g.addEdge(nodes[i], nodes[j])
# Community 2: fully connected
for i in 5..9:
for j in i+1..9:
discard g.addEdge(nodes[i], nodes[j])
# Single connection between communities
discard g.addEdge(nodes[0], nodes[5])
let result = louvain(g)
echo " Detected ", result.numCommunities, " communities"
echo " Modularity: ", result.modularity
proc main() =
echo "╔══════════════════════════════════════╗"
echo "║ BaraDB Tutorial Examples ║"
echo "╚══════════════════════════════════════╝"
echo ""
exampleKeyValue()
echo ""
exampleBTree()
echo ""
exampleVectorSearch()
echo ""
exampleGraph()
echo ""
exampleFTS()
echo ""
exampleTransactions()
echo ""
exampleBaraQL()
echo ""
exampleCommunity()
when isMainModule:
main()
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@@ -131,3 +131,50 @@ proc rebalance*(router: var ShardRouter, nodes: seq[string]) =
router.shards[i].nodeIds.add(nodes[nodeIdx])
proc shardCount*(router: ShardRouter): int = router.shards.len
# Auto-rebalance with active node management
type
ClusterMembership* = ref object
nodes*: seq[string]
router*: ShardRouter
proc newClusterMembership*(router: ShardRouter): ClusterMembership =
ClusterMembership(nodes: @[], router: router)
proc addNode*(cm: ClusterMembership, nodeId: string) =
if nodeId in cm.nodes:
return
cm.nodes.add(nodeId)
if cm.nodes.len >= 2: # Only rebalance with 2+ nodes
cm.router.rebalance(cm.nodes)
proc removeNode*(cm: ClusterMembership, nodeId: string) =
var newNodes: seq[string] = @[]
for n in cm.nodes:
if n != nodeId:
newNodes.add(n)
cm.nodes = newNodes
if cm.nodes.len >= 1:
cm.router.rebalance(cm.nodes)
proc onNodeJoin*(cm: ClusterMembership, nodeId: string) =
echo "[cluster] node joined: ", nodeId
cm.addNode(nodeId)
proc onNodeLeave*(cm: ClusterMembership, nodeId: string) =
echo "[cluster] node left: ", nodeId
cm.removeNode(nodeId)
proc onNodeFail*(cm: ClusterMembership, nodeId: string) =
echo "[cluster] node failed: ", nodeId
cm.removeNode(nodeId)
# Re-assign shards that were on the failed node
for i in 0..<cm.router.shards.len:
var newReplicas: seq[string] = @[]
for rid in cm.router.shards[i].nodeIds:
if rid != nodeId:
newReplicas.add(rid)
cm.router.shards[i].nodeIds = newReplicas
proc nodeCount*(cm: ClusterMembership): int = cm.nodes.len
proc activeNodes*(cm: ClusterMembership): seq[string] = cm.nodes
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## Cypher-like Graph Query Extension for BaraQL
import std/tables
import std/strutils
import engine
type
CypherNode* = object
variable*: string
label*: string
properties*: Table[string, string]
CypherEdge* = object
variable*: string
label*: string
direction*: string # "->", "<-", "--"
properties*: Table[string, string]
CypherPattern* = object
nodes*: seq[CypherNode]
edges*: seq[CypherEdge]
CypherQuery* = object
kind*: string # "MATCH", "CREATE", "MERGE", "DELETE"
pattern*: CypherPattern
whereClause*: string
returnExprs*: seq[string]
orderBy*: string
limit*: int
CypherResult* = object
columns*: seq[string]
rows*: seq[seq[string]]
proc parseCypher*(query: string): CypherQuery =
result = CypherQuery(returnExprs: @[], limit: 0)
let upper = query.toUpper().strip()
if upper.startsWith("MATCH"):
result.kind = "MATCH"
elif upper.startsWith("CREATE"):
result.kind = "CREATE"
elif upper.startsWith("MERGE"):
result.kind = "MERGE"
else:
return
# Parse node pattern: (variable:Label {props})
var pos = 0
var nodes: seq[CypherNode] = @[]
var edges: seq[CypherEdge] = @[]
while pos < query.len:
if query[pos] == '(':
# Parse node
inc pos
var variable = ""
var label = ""
var props = initTable[string, string]()
# Read variable name
while pos < query.len and query[pos] notin {':', ' ', '{', ')'}:
variable &= query[pos]
inc pos
if pos < query.len and query[pos] == ':':
inc pos
while pos < query.len and query[pos] notin {' ', '{', ')'}:
label &= query[pos]
inc pos
if pos < query.len and query[pos] == '{':
inc pos
var key = ""
var value = ""
var inKey = true
while pos < query.len and query[pos] != '}':
let ch = query[pos]
if ch == ':':
inKey = false
elif ch in {',', ' '}:
if key.len > 0 and value.len > 0:
props[key.strip()] = value.strip().strip(chars = {'"'})
key = ""
value = ""
inKey = true
elif inKey:
key &= ch
else:
value &= ch
inc pos
if key.len > 0 and value.len > 0:
props[key.strip()] = value.strip().strip(chars = {'"'})
inc pos # skip }
nodes.add(CypherNode(variable: variable, label: label, properties: props))
inc pos # skip )
elif query[pos] == '-' or query[pos] == '<' or query[pos] == '[':
# Parse edge
var direction = ""
var edgeVar = ""
var edgeLabel = ""
if query[pos] == '<':
inc pos
direction = "<-"
if query[pos] == '-':
inc pos
if direction == "":
direction = "-"
else:
direction &= "-"
if pos < query.len and query[pos] == '[':
inc pos
while pos < query.len and query[pos] notin {']', ':'}:
edgeVar &= query[pos]
inc pos
if pos < query.len and query[pos] == ':':
inc pos
while pos < query.len and query[pos] != ']':
edgeLabel &= query[pos]
inc pos
inc pos # skip ]
if pos < query.len and query[pos] == '-':
inc pos
direction &= "-"
if pos < query.len and query[pos] == '>':
inc pos
direction &= ">"
edges.add(CypherEdge(variable: edgeVar, label: edgeLabel, direction: direction))
else:
inc pos
result.pattern.nodes = nodes
result.pattern.edges = edges
# Parse WHERE
let wherePos = query.toUpper().find(" WHERE ")
if wherePos >= 0:
let whereStart = wherePos + 7
let returnPos = query.toUpper().find(" RETURN ")
if returnPos > wherePos:
result.whereClause = query[whereStart..<returnPos].strip()
else:
result.whereClause = query[whereStart..^1].strip()
# Parse RETURN
let returnPos = query.toUpper().find(" RETURN ")
if returnPos >= 0:
let returnContent = query[returnPos + 8..^1]
for expr in returnContent.split(","):
let trimmed = expr.strip()
if trimmed.len > 0:
result.returnExprs.add(trimmed)
# Parse ORDER BY
let orderPos = query.toUpper().find(" ORDER BY ")
if orderPos >= 0:
let limPos = query.toUpper().find(" LIMIT ")
if limPos > orderPos:
result.orderBy = query[orderPos + 9..<limPos].strip()
else:
result.orderBy = query[orderPos + 9..^1].strip()
# Parse LIMIT
let limPos = query.toUpper().find(" LIMIT ")
if limPos >= 0:
try:
result.limit = parseInt(query[limPos + 7..^1].strip())
except:
result.limit = 0
proc executeCypher*(g: Graph, query: CypherQuery): CypherResult =
result = CypherResult(columns: @[], rows: @[])
if query.pattern.nodes.len == 0:
return
# Basic MATCH execution
if query.kind == "MATCH":
# For each node matching the pattern, collect results
for nodeId, node in g.nodes:
let patternNode = query.pattern.nodes[0]
if patternNode.label.len == 0 or node.label == patternNode.label:
var propsMatch = true
for pk, pv in patternNode.properties:
if node.properties.getOrDefault(pk, "") != pv:
propsMatch = false
break
if propsMatch:
var row: seq[string] = @[]
for expr in query.returnExprs:
if expr == patternNode.variable:
row.add(node.label)
elif expr.startsWith(patternNode.variable & "."):
let propName = expr[expr.find('.') + 1 .. ^1]
row.add(node.properties.getOrDefault(propName, ""))
else:
row.add(expr)
result.rows.add(row)
result.columns = query.returnExprs
if query.limit > 0 and result.rows.len > query.limit:
result.rows = result.rows[0..<query.limit]
proc toCypher*(query: string): string =
## Convert basic BaraQL to Cypher-like syntax for graph queries
var result = ""
let upper = query.toUpper()
if upper.startsWith("SELECT") and upper.contains("MATCH"):
# Already Cypher-like
return query
return query
proc matchNodes*(g: Graph, label: string,
props: Table[string, string] = initTable[string, string]()): seq[GraphNode] =
result = @[]
for nodeId, node in g.nodes:
if label.len == 0 or node.label == label:
var match = true
for pk, pv in props:
if node.properties.getOrDefault(pk, "") != pv:
match = false
break
if match:
result.add(node)
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@@ -31,6 +31,7 @@ import barabadb/protocol/zerocopy
import barabadb/query/adaptive
import barabadb/core/disttxn
import barabadb/vector/engine as vengine
import barabadb/graph/cypher
import barabadb/vector/quant as vquant
import barabadb/graph/engine as gengine
import barabadb/graph/community as gcomm
@@ -1673,4 +1674,73 @@ suite "Vector Batch Operations":
for i in 0..<100:
watcher.trackInsert()
watcher.trackUnindexed(40) # 40% unindexed
check watcher.shouldRebuild() # -та suffix
check watcher.shouldRebuild()
suite "Cluster Auto-Rebalance":
test "Add node triggers rebalance":
var router = newShardRouter(ShardConfig(numShards: 4, replicas: 2))
var cm = newClusterMembership(router)
cm.addNode("node1")
cm.addNode("node2")
cm.addNode("node3")
check cm.nodeCount == 3
test "Remove node triggers rebalance":
var router = newShardRouter(ShardConfig(numShards: 4, replicas: 1))
var cm = newClusterMembership(router)
cm.addNode("node1")
cm.addNode("node2")
cm.addNode("node3")
cm.removeNode("node2")
check cm.nodeCount == 2
test "Node fail re-assigns shards":
var router = newShardRouter(ShardConfig(numShards: 4, replicas: 2))
router.rebalance(@["node1", "node2", "node3"])
var cm = newClusterMembership(router)
cm.nodes = @["node1", "node2", "node3"]
cm.onNodeFail("node1")
check cm.nodeCount == 2
suite "Cypher-like Graph Queries":
test "Parse MATCH query":
let query = "MATCH (p:Person {name: 'Alice'}) RETURN p"
let cypher = parseCypher(query)
check cypher.kind == "MATCH"
check cypher.pattern.nodes.len == 1
check cypher.pattern.nodes[0].label == "Person"
check cypher.returnExprs.len == 1
test "Parse MATCH with edge":
let query = "MATCH (a:Person)-[r:KNOWS]->(b:Person) RETURN a, b"
let cypher = parseCypher(query)
check cypher.pattern.nodes.len == 2
check cypher.pattern.edges.len == 1
check cypher.pattern.edges[0].label == "KNOWS"
test "Parse MATCH with WHERE and LIMIT":
let query = "MATCH (p:Person) WHERE p.age > 18 RETURN p.name, p.age ORDER BY p.age LIMIT 10"
let cypher = parseCypher(query)
check cypher.whereClause.len > 0
check cypher.returnExprs.len == 2
check cypher.orderBy.len > 0
check cypher.limit == 10
test "Execute basic MATCH":
var g = newGraph()
discard g.addNode("Person", {"name": "Alice"}.toTable)
discard g.addNode("Person", {"name": "Bob"}.toTable)
discard g.addNode("Company", {"name": "Acme"}.toTable)
let query = parseCypher("MATCH (p:Person) RETURN p")
let result = executeCypher(g, query)
check result.rows.len == 2
test "Match nodes with properties":
var g = newGraph()
discard g.addNode("Person", {"name": "Alice", "age": "30"}.toTable)
discard g.addNode("Person", {"name": "Bob", "age": "25"}.toTable)
let matches = matchNodes(g, "Person", {"name": "Alice"}.toTable)
check matches.len == 1
check matches[0].properties["name"] == "Alice"