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neo4j_vector.ts
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neo4j_vector.ts
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import neo4j from "neo4j-driver";
import * as uuid from "uuid";
import { Document } from "../document.js";
import { Embeddings } from "../embeddings/base.js";
import { VectorStore } from "./base.js";
export type SearchType = "vector" | "hybrid";
export type DistanceStrategy = "euclidean" | "cosine";
interface Neo4jVectorStoreArgs {
url: string;
username: string;
password: string;
database?: string;
preDeleteCollection?: boolean;
textNodeProperty?: string;
textNodeProperties?: string[];
embeddingNodeProperty?: string;
keywordIndexName?: string;
indexName?: string;
searchType?: SearchType;
retrievalQuery?: string;
nodeLabel?: string;
createIdIndex?: boolean;
}
const DEFAULT_SEARCH_TYPE = "vector";
const DEFAULT_DISTANCE_STRATEGY = "cosine";
/**
* @security *Security note*: Make sure that the database connection uses credentials
* that are narrowly-scoped to only include necessary permissions.
* Failure to do so may result in data corruption or loss, since the calling
* code may attempt commands that would result in deletion, mutation
* of data if appropriately prompted or reading sensitive data if such
* data is present in the database.
* The best way to guard against such negative outcomes is to (as appropriate)
* limit the permissions granted to the credentials used with this tool.
* For example, creating read only users for the database is a good way to
* ensure that the calling code cannot mutate or delete data.
*
* @link See https://js.langchain.com/docs/security for more information.
*/
export class Neo4jVectorStore extends VectorStore {
private driver: neo4j.Driver;
private database: string;
private preDeleteCollection: boolean;
private nodeLabel: string;
private embeddingNodeProperty: string;
private embeddingDimension: number;
private textNodeProperty: string;
private keywordIndexName: string;
private indexName: string;
private retrievalQuery: string;
private searchType: SearchType;
private distanceStrategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY;
_vectorstoreType(): string {
return "neo4jvector";
}
constructor(embeddings: Embeddings, config: Neo4jVectorStoreArgs) {
super(embeddings, config);
}
static async initialize(
embeddings: Embeddings,
config: Neo4jVectorStoreArgs
) {
const store = new Neo4jVectorStore(embeddings, config);
await store._initializeDriver(config);
await store._verifyConnectivity();
const {
preDeleteCollection = false,
nodeLabel = "Chunk",
textNodeProperty = "text",
embeddingNodeProperty = "embedding",
keywordIndexName = "keyword",
indexName = "vector",
retrievalQuery = "",
searchType = DEFAULT_SEARCH_TYPE,
} = config;
store.embeddingDimension = (await embeddings.embedQuery("foo")).length;
store.preDeleteCollection = preDeleteCollection;
store.nodeLabel = nodeLabel;
store.textNodeProperty = textNodeProperty;
store.embeddingNodeProperty = embeddingNodeProperty;
store.keywordIndexName = keywordIndexName;
store.indexName = indexName;
store.retrievalQuery = retrievalQuery;
store.searchType = searchType;
if (store.preDeleteCollection) {
await store._dropIndex();
}
return store;
}
async _initializeDriver({
url,
username,
password,
database = "neo4j",
}: Neo4jVectorStoreArgs) {
try {
this.driver = neo4j.driver(url, neo4j.auth.basic(username, password));
this.database = database;
} catch (error) {
throw new Error(
"Could not create a Neo4j driver instance. Please check the connection details."
);
}
}
async _verifyConnectivity() {
await this.driver.verifyAuthentication();
}
async close() {
await this.driver.close();
}
async _dropIndex() {
try {
await this.query(`
MATCH (n:\`${this.nodeLabel}\`)
CALL {
WITH n
DETACH DELETE n
}
IN TRANSACTIONS OF 10000 ROWS;
`);
await this.query(`DROP INDEX ${this.indexName}`);
} catch (error) {
console.error("An error occurred while dropping the index:", error);
}
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
async query(query: string, params: any = {}): Promise<any[]> {
const session = this.driver.session({ database: this.database });
const result = await session.run(query, params);
return toObjects(result.records);
}
static async fromTexts(
texts: string[],
// eslint-disable-next-line @typescript-eslint/no-explicit-any
metadatas: any,
embeddings: Embeddings,
config: Neo4jVectorStoreArgs
): Promise<Neo4jVectorStore> {
const docs = [];
for (let i = 0; i < texts.length; i += 1) {
const metadata = Array.isArray(metadatas) ? metadatas[i] : metadatas;
const newDoc = new Document({
pageContent: texts[i],
metadata,
});
docs.push(newDoc);
}
return Neo4jVectorStore.fromDocuments(docs, embeddings, config);
}
static async fromDocuments(
docs: Document[],
embeddings: Embeddings,
config: Neo4jVectorStoreArgs
): Promise<Neo4jVectorStore> {
const {
searchType = DEFAULT_SEARCH_TYPE,
createIdIndex = true,
textNodeProperties = [],
} = config;
const store = await this.initialize(embeddings, config);
const embeddingDimension = await store.retrieveExistingIndex();
if (!embeddingDimension) {
await store.createNewIndex();
} else if (store.embeddingDimension !== embeddingDimension) {
throw new Error(
`Index with name "${store.indexName}" already exists. The provided embedding function and vector index dimensions do not match.
Embedding function dimension: ${store.embeddingDimension}
Vector index dimension: ${embeddingDimension}`
);
}
if (searchType === "hybrid") {
const ftsNodeLabel = await store.retrieveExistingFtsIndex();
if (!ftsNodeLabel) {
await store.createNewKeywordIndex(textNodeProperties);
} else {
if (ftsNodeLabel !== store.nodeLabel) {
throw Error(
"Vector and keyword index don't index the same node label"
);
}
}
}
if (createIdIndex) {
await store.query(
`CREATE CONSTRAINT IF NOT EXISTS FOR (n:${store.nodeLabel}) REQUIRE n.id IS UNIQUE;`
);
}
await store.addDocuments(docs);
return store;
}
static async fromExistingIndex(
embeddings: Embeddings,
config: Neo4jVectorStoreArgs
) {
const { searchType = DEFAULT_SEARCH_TYPE, keywordIndexName = "keyword" } =
config;
if (searchType === "hybrid" && !keywordIndexName) {
throw Error(
"keyword_index name has to be specified when using hybrid search option"
);
}
const store = await this.initialize(embeddings, config);
const embeddingDimension = await store.retrieveExistingIndex();
if (!embeddingDimension) {
throw Error(
"The specified vector index name does not exist. Make sure to check if you spelled it correctly"
);
}
if (store.embeddingDimension !== embeddingDimension) {
throw new Error(
`The provided embedding function and vector index dimensions do not match.
Embedding function dimension: ${store.embeddingDimension}
Vector index dimension: ${embeddingDimension}`
);
}
if (searchType === "hybrid") {
const ftsNodeLabel = await store.retrieveExistingFtsIndex();
if (!ftsNodeLabel) {
throw Error(
"The specified keyword index name does not exist. Make sure to check if you spelled it correctly"
);
} else {
if (ftsNodeLabel !== store.nodeLabel) {
throw Error(
"Vector and keyword index don't index the same node label"
);
}
}
}
return store;
}
static async fromExistingGraph(
embeddings: Embeddings,
config: Neo4jVectorStoreArgs
) {
const {
textNodeProperties = [],
embeddingNodeProperty,
searchType = DEFAULT_SEARCH_TYPE,
retrievalQuery = "",
nodeLabel,
} = config;
let _retrievalQuery = retrievalQuery;
if (textNodeProperties.length === 0) {
throw Error(
"Parameter `text_node_properties` must not be an empty array"
);
}
if (!retrievalQuery) {
_retrievalQuery = `
RETURN reduce(str='', k IN ${JSON.stringify(textNodeProperties)} |
str + '\\n' + k + ': ' + coalesce(node[k], '')) AS text,
node {.*, \`${embeddingNodeProperty}\`: Null, id: Null, ${textNodeProperties
.map((prop) => `\`${prop}\`: Null`)
.join(", ")} } AS metadata, score
`;
}
const store = await this.initialize(embeddings, {
...config,
retrievalQuery: _retrievalQuery,
});
const embeddingDimension = await store.retrieveExistingIndex();
if (!embeddingDimension) {
await store.createNewIndex();
} else if (store.embeddingDimension !== embeddingDimension) {
throw new Error(
`Index with name ${store.indexName} already exists. The provided embedding function and vector index dimensions do not match.\nEmbedding function dimension: ${store.embeddingDimension}\nVector index dimension: ${embeddingDimension}`
);
}
if (searchType === "hybrid") {
const ftsNodeLabel = await store.retrieveExistingFtsIndex(
textNodeProperties
);
if (!ftsNodeLabel) {
await store.createNewKeywordIndex(textNodeProperties);
} else {
if (ftsNodeLabel !== store.nodeLabel) {
throw Error(
"Vector and keyword index don't index the same node label"
);
}
}
}
// eslint-disable-next-line no-constant-condition
while (true) {
const fetchQuery = `
MATCH (n:\`${nodeLabel}\`)
WHERE n.${embeddingNodeProperty} IS null
AND any(k in $props WHERE n[k] IS NOT null)
RETURN elementId(n) AS id, reduce(str='', k IN $props |
str + '\\n' + k + ':' + coalesce(n[k], '')) AS text
LIMIT 1000
`;
const data = await store.query(fetchQuery, { props: textNodeProperties });
if (!data) {
continue;
}
const textEmbeddings = await embeddings.embedDocuments(
data.map((el) => el.text)
);
const params = {
data: data.map((el, index) => ({
id: el.id,
embedding: textEmbeddings[index],
})),
};
await store.query(
`
UNWIND $data AS row
MATCH (n:\`${nodeLabel}\`)
WHERE elementId(n) = row.id
CALL db.create.setVectorProperty(n, '${embeddingNodeProperty}', row.embedding)
YIELD node RETURN count(*)
`,
params
);
if (data.length < 1000) {
break;
}
}
return store;
}
async createNewIndex(): Promise<void> {
const indexQuery = `
CALL db.index.vector.createNodeIndex(
$index_name,
$node_label,
$embedding_node_property,
toInteger($embedding_dimension),
$similarity_metric
)
`;
const parameters = {
index_name: this.indexName,
node_label: this.nodeLabel,
embedding_node_property: this.embeddingNodeProperty,
embedding_dimension: this.embeddingDimension,
similarity_metric: this.distanceStrategy,
};
await this.query(indexQuery, parameters);
}
async retrieveExistingIndex() {
let indexInformation = await this.query(
`
SHOW INDEXES YIELD name, type, labelsOrTypes, properties, options
WHERE type = 'VECTOR' AND (name = $index_name
OR (labelsOrTypes[0] = $node_label AND
properties[0] = $embedding_node_property))
RETURN name, labelsOrTypes, properties, options
`,
{
index_name: this.indexName,
node_label: this.nodeLabel,
embedding_node_property: this.embeddingNodeProperty,
}
);
if (indexInformation) {
indexInformation = this.sortByIndexName(indexInformation, this.indexName);
try {
const [index] = indexInformation;
const [labelOrType] = index.labelsOrTypes;
const [property] = index.properties;
this.indexName = index.name;
this.nodeLabel = labelOrType;
this.embeddingNodeProperty = property;
const embeddingDimension =
index.options.indexConfig["vector.dimensions"];
return Number(embeddingDimension);
} catch (error) {
return null;
}
}
return null;
}
async retrieveExistingFtsIndex(
textNodeProperties: string[] = []
): Promise<string | null> {
const indexInformation = await this.query(
`
SHOW INDEXES YIELD name, type, labelsOrTypes, properties, options
WHERE type = 'FULLTEXT' AND (name = $keyword_index_name
OR (labelsOrTypes = [$node_label] AND
properties = $text_node_property))
RETURN name, labelsOrTypes, properties, options
`,
{
keyword_index_name: this.keywordIndexName,
node_label: this.nodeLabel,
text_node_property:
textNodeProperties.length > 0
? textNodeProperties
: [this.textNodeProperty],
}
);
if (indexInformation) {
// Sort the index information by index name
const sortedIndexInformation = this.sortByIndexName(
indexInformation,
this.indexName
);
try {
const [index] = sortedIndexInformation;
const [labelOrType] = index.labelsOrTypes;
const [property] = index.properties;
this.keywordIndexName = index.name;
this.textNodeProperty = property;
this.nodeLabel = labelOrType;
return labelOrType;
} catch (error) {
return null;
}
}
return null;
}
async createNewKeywordIndex(
textNodeProperties: string[] = []
): Promise<void> {
const nodeProps =
textNodeProperties.length > 0
? textNodeProperties
: [this.textNodeProperty];
// Construct the Cypher query to create a new full text index
const ftsIndexQuery = `
CREATE FULLTEXT INDEX ${this.keywordIndexName}
FOR (n:\`${this.nodeLabel}\`) ON EACH
[${nodeProps.map((prop) => `n.\`${prop}\``).join(", ")}]
`;
await this.query(ftsIndexQuery);
}
sortByIndexName(
// eslint-disable-next-line @typescript-eslint/no-explicit-any
values: Array<{ [key: string]: any }>,
indexName: string
// eslint-disable-next-line @typescript-eslint/no-explicit-any
): Array<{ [key: string]: any }> {
return values.sort(
(a, b) =>
(a.index_name === indexName ? -1 : 0) -
(b.index_name === indexName ? -1 : 0)
);
}
async addVectors(
vectors: number[][],
documents: Document[],
// eslint-disable-next-line @typescript-eslint/no-explicit-any
metadatas?: Record<string, any>[],
ids?: string[]
): Promise<string[]> {
let _ids = ids;
let _metadatas = metadatas;
if (!_ids) {
_ids = documents.map(() => uuid.v1());
}
if (!metadatas) {
_metadatas = documents.map(() => ({}));
}
const importQuery = `
UNWIND $data AS row
CALL {
WITH row
MERGE (c:\`${this.nodeLabel}\` {id: row.id})
WITH c, row
CALL db.create.setVectorProperty(c, '${this.embeddingNodeProperty}', row.embedding)
YIELD node
SET c.\`${this.textNodeProperty}\` = row.text
SET c += row.metadata
} IN TRANSACTIONS OF 1000 ROWS
`;
const parameters = {
data: documents.map(({ pageContent, metadata }, index) => ({
text: pageContent,
metadata: _metadatas ? _metadatas[index] : metadata,
embedding: vectors[index],
id: _ids ? _ids[index] : null,
})),
};
await this.query(importQuery, parameters);
return _ids;
}
async addDocuments(documents: Document[]): Promise<string[]> {
const texts = documents.map(({ pageContent }) => pageContent);
return this.addVectors(
await this.embeddings.embedDocuments(texts),
documents
);
}
async similaritySearch(query: string, k = 4): Promise<Document[]> {
const embedding = await this.embeddings.embedQuery(query);
const results = await this.similaritySearchVectorWithScore(
embedding,
k,
query
);
return results.map((result) => result[0]);
}
async similaritySearchVectorWithScore(
vector: number[],
k: number,
query: string
): Promise<[Document, number][]> {
const defaultRetrieval = `
RETURN node.${this.textNodeProperty} AS text, score,
node {.*, ${this.textNodeProperty}: Null,
${this.embeddingNodeProperty}: Null, id: Null } AS metadata
`;
const retrievalQuery = this.retrievalQuery
? this.retrievalQuery
: defaultRetrieval;
const readQuery = `${getSearchIndexQuery(
this.searchType
)} ${retrievalQuery}`;
const parameters = {
index: this.indexName,
k: Number(k),
embedding: vector,
keyword_index: this.keywordIndexName,
query,
};
const results = await this.query(readQuery, parameters);
if (results) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
const docs: [Document, number][] = results.map((result: any) => [
new Document({
pageContent: result.text,
metadata: Object.fromEntries(
Object.entries(result.metadata).filter(([_, v]) => v !== null)
),
}),
result.score,
]);
return docs;
}
return [];
}
}
function toObjects(records: neo4j.Record[]) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
const recordValues: Record<string, any>[] = records.map((record) => {
const rObj = record.toObject();
// eslint-disable-next-line @typescript-eslint/no-explicit-any
const out: { [key: string]: any } = {};
Object.keys(rObj).forEach((key) => {
out[key] = itemIntToString(rObj[key]);
});
return out;
});
return recordValues;
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
function itemIntToString(item: any): any {
if (neo4j.isInt(item)) return item.toString();
if (Array.isArray(item)) return item.map((ii) => itemIntToString(ii));
if (["number", "string", "boolean"].indexOf(typeof item) !== -1) return item;
if (item === null) return item;
if (typeof item === "object") return objIntToString(item);
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
function objIntToString(obj: any) {
const entry = extractFromNeoObjects(obj);
// eslint-disable-next-line @typescript-eslint/no-explicit-any
let newObj: any = null;
if (Array.isArray(entry)) {
newObj = entry.map((item) => itemIntToString(item));
} else if (entry !== null && typeof entry === "object") {
newObj = {};
Object.keys(entry).forEach((key) => {
newObj[key] = itemIntToString(entry[key]);
});
}
return newObj;
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
function extractFromNeoObjects(obj: any) {
if (
// eslint-disable-next-line
obj instanceof (neo4j.types.Node as any) ||
// eslint-disable-next-line
obj instanceof (neo4j.types.Relationship as any)
) {
return obj.properties;
// eslint-disable-next-line
} else if (obj instanceof (neo4j.types.Path as any)) {
// eslint-disable-next-line
return [].concat.apply<any[], any[], any[]>([], extractPathForRows(obj));
}
return obj;
}
function extractPathForRows(path: neo4j.Path) {
let { segments } = path;
// Zero length path. No relationship, end === start
if (!Array.isArray(path.segments) || path.segments.length < 1) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
segments = [{ ...path, end: null } as any];
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
return segments.map((segment: any) =>
[
objIntToString(segment.start),
objIntToString(segment.relationship),
objIntToString(segment.end),
].filter((part) => part !== null)
);
}
function getSearchIndexQuery(searchType: SearchType): string {
const typeToQueryMap: { [key in SearchType]: string } = {
vector:
"CALL db.index.vector.queryNodes($index, $k, $embedding) YIELD node, score",
hybrid: `
CALL {
CALL db.index.vector.queryNodes($index, $k, $embedding) YIELD node, score
RETURN node, score UNION
CALL db.index.fulltext.queryNodes($keyword_index, $query, {limit: $k}) YIELD node, score
WITH collect({node: node, score: score}) AS nodes, max(score) AS max
UNWIND nodes AS n
RETURN n.node AS node, (n.score / max) AS score
}
WITH node, max(score) AS score ORDER BY score DESC LIMIT toInteger($k)
`,
};
return typeToQueryMap[searchType];
}