Problem it solves: Relying only on on-chain reads for every UI view = slow apps, costly queries, and poor UX. Sui’s on-chain state is optimized for security and integrity, not for feeds, search, and history queries.

Goal: Design an off-chain indexing stack that consumes Sui events + checkpoints, builds fast UI views, and still preserves on-chain provenance ✅.

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💡 Why Off-Chain Indexing?

• Querying multiple objects directly = expensive + slow.
• Users expect instant feeds, filters, and search.
• Indexers turn event streams → efficient DB tables for fast UX 🚀.

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🏗 Indexer Architecture Pattern

Here’s the playbook:

1. Event sourcing → Emit compact events from Move modules (mint, list, match, transfer). Include object IDs + minimal context.
2. Checkpoint sync → Consume checkpoints to maintain global ordering and consistency.
3. Normalized storage → Store canonical tables (users, collections, listings, trades) with references to object IDs.
4. Realtime ingestion → Use RPC/WebSocket feeds for low-latency; fall back to checkpoint scans for missed data.
5. Materialized views → Precompute feeds, leaderboards, balances = instant UI responses ⚡.

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🛠 Design Best Practices

• Event schema stability → version events so indexers migrate cleanly.
• No sensitive data → store hashes/references, not raw PII.
• Reconciliation hooks → periodically re-scan on-chain state to catch gaps.
• Idempotency → make event processing safe to retry (no duplicates).

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🔄 Example Pipeline

• Move emits: OrderCreated(collection, token, seller, price)
• Indexer consumes event → inserts into listings table → updates collection_stats.
• UI queries fast tables for listings while finality still verified against checkpoints.

👉 Result: snappy feeds + provable on-chain truth.

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📊 Monitoring Your Indexer

• Track lag (seconds behind chain).
• Measure event processing rate.
• Validate event order per checkpoint.
• Support re-indexing from checkpoint X in case of corruption.

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🎯 Outcome

With a solid indexing stack: ✅ Your UI feels instant. ✅ Complex queries (feeds, filters, history) are cheap + fast. ✅ Users still trust the data since everything links back to on-chain truth.

Off-chain speed ⚡, on-chain integrity 🔒 → the best of both worlds.