What Makes a Solana Indexer Reliable?

A Solana indexer is easy to start and hard to trust.

Receiving a transaction stream is only the beginning. The real work is knowing what has been processed, handling interruptions, and making sure the data in your database still reflects the chain.

A reliable indexer is built around recovery, not only speed.

The stream is not the database

A live stream tells the indexer what is happening now.

Yellowstone gRPC is a strong fit for continuously consuming filtered accounts, transactions, and blocks. It gives the indexer the data it needs to react in real time.

But a stream can disconnect. A consumer can restart. A deployment can fail halfway through a batch.

That means the stream cannot be the only record of progress. The indexer needs its own durable state.

Save a checkpoint

A checkpoint is the point in the chain the indexer knows it has fully processed.

Store the last processed slot alongside the indexed data. Only move that checkpoint forward after the associated writes are complete.

This gives the indexer a clear answer after a restart: begin again from the last confirmed point, rather than guessing what may have been missed.

The checkpoint does not need to be complicated. It needs to be durable and updated in the same workflow as the data it represents.

Design for duplicates

An event may arrive twice. The indexer may process part of a batch before it stops. A recovery pass may read data that is already stored.

This should not create a problem.

Use transaction signatures, account addresses, slots, and instruction indexes to give records stable identities. Then make writes idempotent: processing the same event again should lead to the same final state.

This is what makes recovery safe. Without it, every reconnect becomes a special case.

Use RPC to close the gap

After an interruption, the indexer needs confirmed state.

Use RPC to fetch blocks, transactions, or account data around the saved checkpoint. Rebuild the missing range, update the local state, then resume the live stream.

The live stream provides speed. RPC provides the confirmed reference point.

Both are useful, but they do different jobs.

Separate raw events from application state

Store enough raw chain data to explain how your application state was produced.

Then build the views your product needs: token balances, portfolio history, trade activity, protocol positions, or program-specific records.

This separation makes it possible to change an application view without replaying the entire product logic from memory. It also makes debugging much easier when users ask why a number changed.

The simple rule

A reliable indexer can answer three questions at any time:

• What slot have we fully processed?
• Can we safely process this event again?
• How do we rebuild the data after a gap?

If those answers are clear, a fast stream becomes a dependable system—not just a fast source of messages.