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A DBA Put 11 Systems on the Scale: Distributed Databases Lost Every Time

By 倔强的石头_ ·
Read original on juejin.cn ↗ Google Translate ↗ Alt translation

Distributed database marketing pushes teams toward sharding they don't need. This hands-on evaluation shows how to measure your own systems and arrive at a defensible 'no' before spending on extra nodes, licenses, and operational overhead.

Summary

When a colleague suggested moving the new order creation platform to a distributed database, the annual capacity planning meeting ballooned into a 40-minute argument with no conclusion. The DBA was handed a one-page decision paper. The result is a practical framework that first dismantles the word "distributed" into four distinct usages: native sharding, the shard-plus-proxy pattern (still single-node underneath), multi-tenant virtualization on a cluster, and running the distributed system as a single node. Half the teams claiming to have gone distributed are actually on the multi-tenant mode with no sharding at all.

The comparison table across dimensions like read/write scaling, latency, consistency, reliability, and cost shows that shared-storage centralization (the Oracle RAC style) achieves the highest consistency and low latency, while native distributed suffers on latency and costs more overall. The author then maps common business scenarios: core transactions with high concurrency and simple statements fit either distributed sharding or centralized shared storage; CRM/ERP with complex queries favor centralized; data warehouses and HTAP workloads justify native distributed. Across their own 11 systems, including a core transaction DB under 1TB with 3,000 peak concurrency and a planned order platform projecting 2TB and 8,000 concurrent, none meet the common threshold for distribution (TB-scale data and 10k concurrency). The conclusion: no system requires distribution.

The paper ends with three decision questions: will data stably exceed 10TB in three years with concurrency clearly above 10k; is there a definite Oracle RAC replacement requirement; is the workload already cloud-native with elastic spikes? Only if the first is true does distribution become mandatory. The DBA also reviews KingbaseES (KES) for centralized selection, highlighting Oracle compatibility, a shared-storage cluster for RAC replacement, multi-model support for relational, document, time-series, and vector data, and domestic CPU/OS certification. The final advice: decide on architecture before choosing a product.

Takeaways
— The word 'distributed' covers four distinct uses: native sharding, shard-plus-proxy over single-node databases, multi-tenant clusters, and single-node deployment of a distributed product.
— About half of teams claiming to have gone distributed are actually running multi-tenant mode without any sharding.
— Shared-storage centralized architecture (the Oracle RAC style) matches distributed on read scaling and beats it on consistency and latency.
— Native distributed has higher latency due to multiple routing and coordination layers, making it unsuitable for latency-sensitive core transactions.
— A common industry threshold for needing distribution is TB-scale data and 10k peak concurrency; below that, centralized is the more rational choice.
— The author's 11 systems, including a core transaction DB at 3,000 peak concurrency and a planned order platform at 8,000 concurrency, all fall below that threshold.
— Oracle RAC replacement is a centralized shared-storage requirement, not a reason to adopt distributed.
— Three decision questions settle the debate: data volume stable above 10TB and concurrency above 10k; a definite Oracle RAC replacement need; cloud-native elasticity needs. Only the first mandates distribution.
Conclusions

Reducing an emotionally charged architectural debate to three measurable thresholds is a practical antidote to vendor-driven hype.

Treating 'distributed' as a single category obscures that most real deployments are multi-tenant or single-node, letting teams pay distributed license costs without receiving distributed capabilities.

The comparison table shows shared-storage centralized can match distributed on read scaling while achieving higher consistency and lower latency, making it a strong best-of-both-worlds option for core transactions.

Concepts & terms
Shared-storage cluster
A centralized database architecture where multiple instances attach to the same shared storage, like Oracle RAC. It provides high availability and read scaling without data sharding, preserving low latency and single-copy consistency.
Multi-tenant mode
In a distributed database context, running many business systems as tenants on one cluster, often without sharding. It centralizes management but can create resource redundancy and fault propagation.
Pseudo-distributed
An informal term for deploying a distributed database in single-node or multi-tenant mode without actual sharding, so the system behaves like a centralized database while costing like a distributed one.
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