Gel 是一个开源 PostgreSQL 数据层，针对从开发到生产的快速周期进行了优化。它提供高层的强类型图状数据模型、可组合的层次查询语言、完整的 SQL 支持、迁移、Auth 和 AI 模块。

如果你在 Colab 中打开这个 Notebook，可能需要先安装 LlamaIndex 🦙。

! pip install gel llama-index-vector-stores-gel

! pip install llama-index

# import logging
# import sys

# Uncomment to see debug logs
# logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
# logging.getLogger().addHandler(logging.StreamHandler(stream=sys.stdout))

from llama_index.core import SimpleDirectoryReader, StorageContext
from llama_index.core import VectorStoreIndex
from llama_index.vector_stores.gel import GelVectorStore
import textwrap
import openai

设置 OpenAI

第一步是配置 OpenAI 密钥。它将用于为加载到索引中的文档创建嵌入

import os

os.environ["OPENAI_API_KEY"] = "<your key>"
openai.api_key = os.environ["OPENAI_API_KEY"]

下载数据

!mkdir -p 'data/paul_graham/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/paul_graham/paul_graham_essay.txt' -O 'data/paul_graham/paul_graham_essay.txt'

加载文档

使用 SimpleDirectoryReader 加载存储在 data/paul_graham/ 中的文档

documents = SimpleDirectoryReader("./data/paul_graham").load_data()
print("Document ID:", documents[0].doc_id)

创建数据库

为了将 Gel 用作向量存储的后端，你需要一个可用的 Gel 实例。幸运的是，它不一定涉及 Docker 容器或任何复杂的东西，除非你希望如此！

要设置本地实例，请运行：

! gel project init --non-interactive

如果你使用 Gel Cloud（你应该使用！），请在该命令中再添加一个参数：

终端窗口

gel project init --server-instance <org-name>/<instance-name>

有关运行 Gel 的完整方式列表，请查看参考文档中的 Running Gel 部分。

设置 schema

Gel schema 是对应用程序数据模型的明确高层描述。除了让你准确定义数据的布局方式外，它还驱动 Gel 的许多强大功能，例如链接、访问策略、函数、触发器、约束、索引等。

LlamaIndex 的 GelVectorStore 期望 schema 采用以下布局：

schema_content = """
using extension pgvector;

module default {
    scalar type EmbeddingVector extending ext::pgvector::vector<1536>;

    type Record {
        required collection: str;
        text: str;
        embedding: EmbeddingVector;
        external_id: str {
            constraint exclusive;
        };
        metadata: json;

        index ext::pgvector::hnsw_cosine(m := 16, ef_construction := 128)
            on (.embedding)
    }
}
""".strip()

with open("dbschema/default.gel", "w") as f:
    f.write(schema_content)

为了将 schema 更改应用到数据库，请使用 Gel 的迁移工具运行迁移：

! gel migration create --non-interactive
! gel migrate

从现在开始，GelVectorStore 可以用作 LlamaIndex 中任何其他向量存储的直接替代品。

创建索引

vector_store = GelVectorStore()

storage_context = StorageContext.from_defaults(vector_store=vector_store)
index = VectorStoreIndex.from_documents(
    documents, storage_context=storage_context, show_progress=True
)
query_engine = index.as_query_engine()

查询索引

现在我们可以使用索引来提问了。

response = query_engine.query("What did the author do?")

print(textwrap.fill(str(response), 100))

response = query_engine.query("What happened in the mid 1980s?")

print(textwrap.fill(str(response), 100))

元数据过滤器

GelVectorStore 支持在节点中存储元数据，并在检索步骤中基于该元数据进行过滤。

下载 git 提交数据集

!mkdir -p 'data/git_commits/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/csv/commit_history.csv' -O 'data/git_commits/commit_history.csv'

import csv

with open("data/git_commits/commit_history.csv", "r") as f:
    commits = list(csv.DictReader(f))

print(commits[0])
print(len(commits))

添加带有自定义元数据的节点

# Create TextNode for each of the first 100 commits
from llama_index.core.schema import TextNode
from datetime import datetime
import re

nodes = []
dates = set()
authors = set()
for commit in commits[:100]:
    author_email = commit["author"].split("<")[1][:-1]
    commit_date = datetime.strptime(
        commit["date"], "%a %b %d %H:%M:%S %Y %z"
    ).strftime("%Y-%m-%d")
    commit_text = commit["change summary"]
    if commit["change details"]:
        commit_text += "\n\n" + commit["change details"]
    fixes = re.findall(r"#(\d+)", commit_text, re.IGNORECASE)
    nodes.append(
        TextNode(
            text=commit_text,
            metadata={
                "commit_date": commit_date,
                "author": author_email,
                "fixes": fixes,
            },
        )
    )
    dates.add(commit_date)
    authors.add(author_email)

print(nodes[0])
print(min(dates), "to", max(dates))
print(authors)

vector_store = GelVectorStore()

index = VectorStoreIndex.from_vector_store(vector_store=vector_store)
index.insert_nodes(nodes)

print(index.as_query_engine().query("How did Lakshmi fix the segfault?"))

应用元数据过滤器

现在，我们可以在检索节点时按提交作者或日期进行过滤。

from llama_index.core.vector_stores.types import (
    MetadataFilter,
    MetadataFilters,
)

filters = MetadataFilters(
    filters=[
        MetadataFilter(key="author", value="mats@timescale.com"),
        MetadataFilter(key="author", value="sven@timescale.com"),
    ],
    condition="or",
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("What is this software project about?")

for node in retrieved_nodes:
    print(node.node.metadata)

filters = MetadataFilters(
    filters=[
        MetadataFilter(key="commit_date", value="2023-08-15", operator=">="),
        MetadataFilter(key="commit_date", value="2023-08-25", operator="<="),
    ],
    condition="and",
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("What is this software project about?")

for node in retrieved_nodes:
    print(node.node.metadata)

应用嵌套过滤器

在上面的示例中，我们使用 AND 或 OR 组合了多个过滤器。我们也可以组合多组过滤器。

filters = MetadataFilters(
    filters=[
        MetadataFilters(
            filters=[
                MetadataFilter(
                    key="commit_date", value="2023-08-01", operator=">="
                ),
                MetadataFilter(
                    key="commit_date", value="2023-08-15", operator="<="
                ),
            ],
            condition="and",
        ),
        MetadataFilters(
            filters=[
                MetadataFilter(key="author", value="mats@timescale.com"),
                MetadataFilter(key="author", value="sven@timescale.com"),
            ],
            condition="or",
        ),
    ],
    condition="and",
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("What is this software project about?")

for node in retrieved_nodes:
    print(node.node.metadata)

上述内容可以通过使用 IN 运算符来简化。GelVectorStore 支持 in、nin 和 contains，用于将元素与列表进行比较。

filters = MetadataFilters(
    filters=[
        MetadataFilter(key="commit_date", value="2023-08-01", operator=">="),
        MetadataFilter(key="commit_date", value="2023-08-15", operator="<="),
        MetadataFilter(
            key="author",
            value=["mats@timescale.com", "sven@timescale.com"],
            operator="in",
        ),
    ],
    condition="and",
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("What is this software project about?")

for node in retrieved_nodes:
    print(node.node.metadata)

# Same thing, with NOT IN
filters = MetadataFilters(
    filters=[
        MetadataFilter(key="commit_date", value="2023-08-01", operator=">="),
        MetadataFilter(key="commit_date", value="2023-08-15", operator="<="),
        MetadataFilter(
            key="author",
            value=["mats@timescale.com", "sven@timescale.com"],
            operator="nin",
        ),
    ],
    condition="and",
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("What is this software project about?")

for node in retrieved_nodes:
    print(node.node.metadata)

# CONTAINS
filters = MetadataFilters(
    filters=[
        MetadataFilter(key="fixes", value="5680", operator="contains"),
    ]
)

retriever = index.as_retriever(
    similarity_top_k=10,
    filters=filters,
)

retrieved_nodes = retriever.retrieve("How did these commits fix the issue?")
for node in retrieved_nodes:
    print(node.node.metadata)