# The Capacity of Private Information Retrieval from Heterogeneous Uncoded Caching Databases

arXiv: https://arxiv.org/abs/1902.09512 · HTML: https://mlsanity.com/paper/1902.09512/

## Key facts

- Cited by 2 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 25 Feb 2019.

## Built on by (most cited first, 2 of 2)

- [Private Counterfactual Retrieval With Immutable Features](https://mlsanity.com/paper/2411.10429/) (2024)
- [What If, But Privately: Private Counterfactual Retrieval](https://mlsanity.com/paper/2508.03681/) (2025)

## Abstract (arXiv)

We consider private information retrieval (PIR) of a single file out of K files from N non-colluding databases with heterogeneous storage constraints m=(m1, cdots, mN). The aim of this work is to jointly design the content placement phase and the information retrieval phase in order to minimize the download cost in the PIR phase. We characterize the optimal PIR download cost as a linear program. By analyzing the structure of the optimal solution of this linear program, we show that, surprisingly, the optimal download cost in our heterogeneous case matches its homogeneous counterpart where all databases have the same average storage constraint μ=frac1N sumn=1N mn. Thus, we show that there is no loss in the PIR capacity due to heterogeneity of storage spaces of the databases. We provide the optimum content placement explicitly for N=3.