8/26/2024

Saving Indexes in LlamaIndex: Practical Steps

When working with the wonderful world of data and generative AI, knowing how to save your work efficiently is a BIG deal. With LlamaIndex, storing your indexes properly can save you tons of time & even future headaches. Think about it: you’ve spent all that time LOADING, INDEXING, and readying your data for some smooth queries. You wouldn’t wanna start from scratch again, right? So, let’s dive into how you can save indexes in LlamaIndex with a detailed guide that’ll make the process easier for you!

1. Understanding Why You Need to Save Indexes

At its core, LlamaIndex allows you to create and work with indexes which are super helpful when you want to query data efficiently. The default behavior is to store this indexed data in-memory, which is neat for quick tests or small datasets. However, if you’re dealing with large datasets or you just want to avoid the time cost of having to re-index all over again, you need to store that data on disk. It’s all about avoiding re-indexing. Trust me, it’s a GAME CHANGER!

2. Persisting to Disk

Persisting your index to disk is pretty straightforward in LlamaIndex. The built-in
1 .persist()
method allows you to save your indexed data to a specified location. Here’s a simple code snippet to get you started:
1 index.storage_context.persist(persist_dir="<persist_dir>")
This command will create a directory with the name you specify in
1 <persist_dir>
and store your indexed data there. You can even save a Composable Graph by doing:
1 graph.root_index.storage_context.persist(persist_dir="<persist_dir>")

2.1. Load Your Persisted Index

Once you’ve saved your index, you wanna load it up when you need it! To avoid unnecessary loading & re-indexing, you can load your previously persisted index using this approach:
1 2 3 4 5 6 7 from llama_index.core import StorageContext, load_index_from_storage # rebuild storage context storage_context = StorageContext.from_defaults(persist_dir="<persist_dir>") # load index index = load_index_from_storage(storage_context)
Tip: If you have initialized your index with any custom transformations, embedding models, etc., you'll need to pass options during the loading process. Make sure you manage global settings to help with that!

3. Using Vector Stores

When discussing indexes, one common type you’ll encounter is the VectorStoreIndex. Creating embeddings through API calls can be pretty expensive in terms of time & computational resources. Hence, it's important to save these embeddings when using LlamaIndex to avoid the repeated overhead of re-indexing.
LlamaIndex supports a bunch of vector stores. Let’s take Chroma, an open-source vector store, as an example. First, you’ll need to install it:
1 pip install chromadb
Once that’s done, you can use Chroma to store your embeddings! Here’s a sneak peek of what the code looks like:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 import chromadb from llama_index.core import VectorStoreIndex, SimpleDirectoryReader from llama_index.vector_stores.chroma import ChromaVectorStore from llama_index.core import StorageContext # load documents documents = SimpleDirectoryReader("./data").load_data() # initialize client, setting path save data db = chromadb.PersistentClient(path="./chroma_db") # create collection chroma_collection = db.get_or_create_collection("quickstart") # assign chroma vector_store to context vector_store = ChromaVectorStore(chroma_collection=chroma_collection) storage_context = StorageContext.from_defaults(vector_store=vector_store) # create index index = VectorStoreIndex.from_documents(documents, storage_context=storage_context)
The query engine can be created like this:
1 2 3 query_engine = index.as_query_engine() response = query_engine.query("What is the meaning of life?") print(response)

3.1. Loading Stored Embeddings

If you already have stored embeddings, you don’t need to load documents again or create a new VectorStoreIndex. Instead, load the stored vectors directly:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 import chromadb from llama_index.core import VectorStoreIndex from llama_index.vector_stores.chroma import ChromaVectorStore from llama_index.core import StorageContext # initialize client db = chromadb.PersistentClient(path="./chroma_db") # collection chroma_collection = db.get_or_create_collection("quickstart") # assign chroma vector_store to context vector_store = ChromaVectorStore(chroma_collection=chroma_collection) storage_context = StorageContext.from_defaults(vector_store=vector_store) # load index from stored vectors index = VectorStoreIndex.from_vector_store(vector_store, storage_context=storage_context) # create query engine query_engine = index.as_query_engine() response = query_engine.query("What does llama2 mean?") print(response)
Tip: Check out more comprehensive examples using Chroma if you wanna dive deeper into this!

4. Inserting New Documents/Nodess

So, you’ve created your index & stored it. But what if you want to add any new documents to the index? It's simple to do so with the
1 insert
method.
Here's how you can insert new documents:
1 2 3 4 5 from llama_index.core import VectorStoreIndex index = VectorStoreIndex([]) # create an empty index documents = ["new_doc1", "new_doc2"] # your new documents for doc in documents: index.insert(doc)
Make sure to check out the document management how-to for more examples on managing these documents!

5. Best Practices When Saving Indexes

Alright, you've got the basics. But if you really want to master saving your indexes, here are some best practices you can follow:
  • Be Consistent: Always save your indexes after significant updates. Don’t wait until the last minute!
  • Organize Directories: Keep your persist directories organized to make future loads cleaner.
  • Monitor Changes: Keep an eye on how your new data affects existing indexes. This can save you future troubles.
  • Optimize Performance: Use different vector stores according to the needs of your project.

6. Conclusion

Saving indexes in LlamaIndex is crucial for efficient data querying and managing your generative AI applications. Whether you’re using regular indices or vector store indices, knowing the right steps to persist your data can drastically optimize your workflow.
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