We operate one of the largest short video streaming platforms in the world, serving billions of global users every day. Similar to other platforms, we employ Adaptive Bitrate (ABR) streaming, which adaptively selects an appropriate representation from a group of video representations forming a bitrate ladder. In this paper, instead of developing yet another ABR algorithm, we optimize the bitrate ladder configuration, which constitutes the decision space of ABR, by developing a system called TLadder.

The last decade has seen a remarkable rise in specialized database systems. Systems for transaction processing, data warehousing, time series analysis, full-text search, data lakes, in-memory caching, document storage, queuing, graph processing, and geo-replicated operational workloads are now available to developers. A belief has taken hold that a single general-purpose database is not capable of running varied workloads at a reasonable cost with strong performance, at the level of scale and concurrency people demand today. There is value in specialization, but the complexity and cost of using multiple specialized systems in a single application environment is becoming apparent. This realization is driving developers and IT decision makers to seek databases capable of powering a broader set of use cases when looking to adopt a new database. Hybrid transaction and analytical (HTAP) databases have been developed to try to tame some of this chaos.

Real-time analytics on massive datasets has become a very common need in many enterprises. These applications require not only rapid data ingest, but also quick answers to analytical queries operating on the latest data. MemSQL is a distributed SQL database designed to exploit memory-optimized, scale-out architecture to enable real-time transactional and analytical workloads which are fast, highly concurrent, and extremely scalable. Many analytical queries in MemSQL's customer workloads are complex queries involving joins, aggregations, sub-queries, etc. over star and snowflake schemas, often ad-hoc or produced interactively by business intelligence tools. These queries often require latencies of seconds or less, and therefore require the optimizer to not only produce a high quality distributed execution plan, but also produce it fast enough so that optimization time does not become a bottleneck. In this paper, we describe the architecture of the MemSQL Query Optimizer and the design choices and innovations which enable it quickly produce highly efficient execution plans for complex distributed queries. We discuss how query rewrite decisions oblivious of distribution cost can lead to poor distributed execution plans, and argue that to choose high-quality plans in a distributed database, the optimizer needs to be distribution-aware in choosing join plans, applying query rewrites, and costing plans. We discuss methods to make join enumeration faster and more effective, such as a rewrite-based approach to exploit bushy joins in queries involving multiple star schemas without sacrificing optimization time. We demonstrate the effectiveness of the MemSQL optimizer over queries from the TPC-H benchmark and a real customer workload.

We report the development of an artificial haircell (AHC) fabricated using two methods: (1) silicon bulk micromachining and (2) polymer surface micromachining. Both methods leverage efficient three dimensional assembly of microstructures. The AHC is modeled after biological hair cells, a common and versatile mechanoreceptor in biology. The design, fabrication process, along with testing results are discussed in the paper.

We report the development of a multi-modal, flexible tactile sensing skin based on polymer substrates and integrated micromachining technology with increased mechanical robustness relative to silicon tactile devices. This polymer-based tactile skin is very unique because it includes the following sensing modalities beyond surface roughness and contact force measurement: thermal conductivity, hardness, temperature, and its own curvature. These new modalities allow the demonstrated tactile sensors to characterize an object or a contact event in a more comprehensive fashion. Sensing is accomplished via thin film metal gold heaters, nickel RTD's (Resistance Temperature Device), and NiCr (nichrome) strain gauges. Experimental characterization of the sensors' performance and potential for application to robotics are presented.