Panagiotis Bailis
Senior Software Engineer - Vector Search at Elastic
Thessaloniki, Macedonia and Thrace, Greece
Summary
🤩
Rockstar🎓
Top SchoolPanagiotis Bailis is a Senior Software Engineer with 12 years of experience specializing in information retrieval, machine learning and NLP, currently focused on vector search at Elastic. He has a strong background in production search systems from senior roles at Cookpad and Atypon and contributed concrete enhancements to the widely used open-source Elasticsearch project, adding exists-query support for sparse vectors and ensuring backward-compatible index behavior. Comfortable across backend systems and data mapping, he blends research-informed thinking (MSc with Distinction from Edinburgh) with practical engineering that ships at scale. Based in Thessaloniki, Greece, he brings deep expertise in search internals and testing, and a knack for spotting edge cases—such as non-strictly increasing doc IDs—that break assumptions in real-world systems. Colleagues describe him as a pragmatic problem-solver who elevates search relevance while keeping production reliability front and center.
12 years of coding experience
9 years of employment as a software developer
Master of Science (MSc) with Distinction, Master of Science (MSc) with Distinction at The University of EdinburghBachelor's degree, Bachelor's degree at Aristoteleion Panepistimion Thessalonikis
Greek, English
Github Skills (13)
lucene10
javas10
elasticsearch10
search-engine10
elasticsearchquery10
aws-elasticsearch10
java10
elasticsearch-api10
amazon-elasticsearch10
testing9
data-structure7
data-structures7
algorithms7
Programming languages (3)
Github contributions (5)
elastic/elasticsearch
Sep 2023 - Feb 2025
Free and Open Source, Distributed, RESTful Search Engine
Role in this project:
Back-end Developer
Back-end DeveloperContributions:364 reviews, 214 PRs, 86 pushes in 1 year 5 months
Contributions summary:Panagiotis focused on enhancing the functionality of the Elasticsearch search engine by implementing support for "exists" queries for sparse_vector fields. They added non-null `sparse_vector` fields to `_field_names` and introduced a new IndexVersion to ensure backward compatibility. The user also refactored and added tests to an example plugin to account for non-strictly increasing doc IDs in the results. These changes involved modifying Java code related to data mapping, querying, and testing.
restfulsearch-engineopensearchelasticsearchjava
pmpailis/rl-monopoly
Oct 2013 - Mar 2021
Contributions:21 commits, 12 pushes, 4 branches in 7 years 5 months
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