The initial project (v1/v2) was developed by SQLI, a French IT services company, with a custom PHP framework and Smarty templates. The legacy code contained 398 SVN revisions covering 2010-2013.

When I joined SQLI, 5 full-time PHP developers were dedicated to the project. Over time, I took on a growing share of the technical scope, eventually handling the entire perimeter on my own - a role that naturally evolved with my expertise and the autonomy that came with the PME environment. After covering the full perimeter solo for a while, I asked for reinforcement and obtained the hiring of a second developer.

From 2014-2016, our new Medialeads team undertook a complete rewrite of the platform, progressively migrating from the custom framework to Symfony 2/3 while maintaining the public site on a lighter custom MVC framework.

The platform was multilingual (7 languages), multi-country, with high product data volumes, and the need to maintain compatibility with existing supplier data feeds - all hosted on fully self-managed OVH dedicated servers: we handled absolutely everything ourselves, from system configuration to deployments.

• Massive data management & SQL optimization: mastery of SQL normal forms (1NF, 2NF, 3NF, BCNF), all join types (INNER/LEFT/RIGHT/CROSS/SELF), advanced indexing (B-tree, composite, covering indexes), constant `EXPLAIN ANALYZE` plan analysis, MySQL master-slave replication and Memcache caching. Ran nightly batches of several hours to recompute stock levels, prices and promotions across the whole catalog - at that scale a missing index could turn a 50 ms query into a 30-second timeout, so every millisecond saved per query compounded over millions of executions.
• Search engines & indexing: hands-on progression across four generations of search engines - (1) MySQL LIKE / FULLTEXT (MyISAM/InnoDB), (2) PostgreSQL full-text search with `tsvector`/`tsquery`, GIN indexes and `to_tsvector`/`ts_rank` functions, (3) Apache Solr indexing hundreds of thousands of products with advanced faceting (categories, colors, prices, suppliers), spell-checking and custom relevance scoring, (4) Elasticsearch with inverted indexes, multilingual analyzers (stemming, tokenization, normalization), TF-IDF scoring, aggregations and facets. Learned the deep differences between a relational engine and a dedicated search engine.
• Complex algorithms & business rules: design and implementation of numerous complex algorithms and intricate business rules - for example computing every possible combination of price, product variants and availability (Cartesian product / combinatorial explosion generating thousands of combinations per product across sizes, colors, quantities, marking types, marking zones and finishes). Mastery of dynamic pricing rule modeling and business decision engines.
• Mastered Symfony 2/3 ecosystem at production scale (Propel, Doctrine, bundles, services, security, WSSE)
• Developed strong skills in legacy code migration - transitioning from SVN monolith to Git-based microservices without downtime
• Built domain knowledge in B2B promotional products market, data feed automation, and multi-country e-commerce
• Learned to coordinate within a small team where each developer owns significant portions of the codebase

With todays standards and hindsight, a few choices could have been made differently - each decision made sense within the constraints of its era:

• Adopting a single framework from the start rather than maintaining a custom PHP framework alongside Symfony, though historical context justified coexistence during migration.
• Setting up CI/CD from the GitHub migration (January 2016) - Jenkins, Travis CI or GitLab CI were available even if GitHub Actions did not exist yet.
• Using Docker for dev and deploy environments, though Proxmox was the mature virtualization standard for PHP PME at the time.
• Centralizing data access via a single API rather than direct MySQL from each service - a pattern that only became widespread after 2017.