Introduction of Search

Author: Reggie Lai, Engineering manager of Search Feature & Infra

Search is one of the common and important functions of online services. It provides an efficient way for users to find what they are looking for. As an online marketplace, Mercari leverages and optimizes our search capability to delight our users in their item discovery experience.
In this short article, I’ll briefly introduce the concept of search, how we use it in Mercari and what we’re trying to achieve in the near future.

What is Search

Search is a function or process to retrieve information from corresponding resources by search queries. The information can be all kinds of digital content such as text, web pages, images and video, etc. The resources are generally indexed in a way optimized for such retrieval processes. The retrieved information is called search result, and usually ranked in an order of relevancy to search queries.

Search in Mercari

Mercari is an online marketplace for selling/buying items and Search is the most essential approach to match these two activities. The typical user journey is as follow:

  • buyers submit keywords relevant to the items they want to search
  • the search result of items listed by sellers will be returned in a specific order

High Level Architecture

Mission & Focus Areas

Search as a whole is on a mission to connect buyers and sellers, by understanding their needs to make efficient and enjoyable experiences in the item discovery process. As an ultimate goal to help buyers to get what they want, and as a result, sellers can sell their listed items successfully.

There are several teams under this big search umbrella but focusing on different areas, such as but not limited to the following:

  • user interface and client-side presentation
  • ranking optimization and supportive features for search results
  • data aggregation, handling and storage
  • natural language processing and linguistic components
  • distributed infrastructure and production serving

Search Infra High Level Direction

The high level direction for search infra/platform are:

  • Robust Foundation: the system maintainability enhancement and computing resource optimization are the keys to provide a robust and sustainable foundation for all search applications.
  • Speed for Product Development: make search platform as a service for all search applications. Product development can focus more on business logic implementation for idea experiments and feature releases.


There are many pieces and domains in search. Mercari has teams putting effort in all aspects together to satisfy our customers. As a whole search is a complicated process but the goal is simple. Hope this article helps in high level understanding.

We Are Hiring

Search is the primary user journey of using Mercari service. The search quality is critical for user experience and revenue of the whole organization. In the search infra/platform team you’ll be able to get your hands on the underlying infrastructures and see how search really works under the hood. Your expertise in search engine core and large-scale distributed systems will ultimately influence our product and business to a significant degree.

Do you like large scales? We’re dealing with hundreds of millions listings and serving tens of thousands requests during peak time. If you’re experienced in search engines and cloud services with good command in programming, we’d like to invite you to work with us!

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