X-Engine

Abstract

Alibaba runs the largest e-commerce platform in the world serving more than 600 million customers, with a GMV (gross merchandise value) exceeding USD 768 billion in FY2018. Online e-commerce transactions have three notable characteristics: (1) drastic increase of transactions per second with the kickoff of major sales and promotion events, (2) a large number of hot records that can easily overwhelm system buffers, and (3) quick shift of the "temperature" (hot v.s. warm v.s. cold) of different records due to the availability of promotions on different categories over different short time periods. For example, Alibaba's OLTP database clusters experienced a 122 times increase of transactions on the start of the Singles' Day Global Shopping Festival in 2018, processing up to 491,000 sales transactions per second which translate to more than 70 million database transactions per second. To address these challenges, we introduce X-Engine, a write-optimized storage engine of POLARDB built at Alibaba, which utilizes a tiered storage architecture with the LSM-tree (log-structured merge tree) to leverage hardware acceleration such as FPGA-accelerated compactions, and a suite of optimizations including asynchronous writes in transactions, multi-staged pipelines and incremental cache replacement during compactions. Evaluation results show that X-Engine has outperformed other storage engines under such transactional workloads. CCS Concepts • Information systems → Data access methods; DBMS engine architectures; Database transaction processing.

Tailored Mesoporous Inorganic Biomaterials: Assembly, Functionalization, and Drug Delivery Engineering

“…In recent years, photoactivatable drug delivery system has been developed as potential responsive delivery technology, and illumination is employed as an efficient stimulus to control the drug‐release dynamics, such as red light, blue light, low‐power UV light (365 nm), and NIR light. [ 95,96,104,146,213,248–250 ] Light adsorbing species or photosensitizers, such as CdS, [ 104 ] TiO 2 , [ 192 ] WS 2 , [ 10 ] graphene oxide, [ 251 ] and carbon dots, [ 252 ] can be grafted or deposited on the surface of mesoporous materials to block these pores. Once these active ingredients are exposed to light illuminations, the gatekeepers can change the states to achieve a controllable drug release in targeted area.…”

“…For drug delivery, despite artificial biomaterials exhibiting great potentials and intriguing features in various drug‐loaded engineering, especially for anticancer drugs and bone‐tissue regulation, single‐component mesoporous biomaterials are almost impossible to accomplish the whole delivery‐release task, which is limited by their inherent performance defects, including loading capacity, biocompatibility, stimuli sensitivity, and self‐degradation capacity. [ 79–82 ] Thus, these mesoporous biomaterials were usually modified to construct multicomponent nanocarriers with diverse techniques, such as polymer grafting, [ 26,83,84 ] bond bridging, [ 85–87 ] doping, [ 88,89 ] quantum dot capping, [ 90–93 ] and coating, [ 94–96 ] which can remarkably improve physicochemical properties of these biomaterials to realize drug therapy. In reality, traditional DDSs contain three indispensable segments.…”

JellyFish

“…Both the proposed work and X-Engine [32] enhance the skip list data structure to reduce the overhead of MVCC under highly concurrent workloads. JellyFish handles an update as an insertion supporting MVCC, but it inserts updates into the per-key list, rather than the skip list, thereby eliminating the overhead of traversing redundant data copies.…”

“…The source code for X-Engine is publicly unavailable, and we interpret its internal implementation based on its publication[32].…”

Preparation and characterization of one‐component polyurethane powder adhesives by the solution polymerization technology

“…Although the method of mechanical pulverization was relatively simple, it required secondary processing and the process was complex. Zhang et al . invented the waterborne PU powder material by the freeze‐dried PU emulsion.…”