Before My PhD Journey
My PhD journey is about to begin. As I sit at my desk now, the familiar street outside my window looks the same, but inside me a long farewell has already started. Hangzhou in summer can be muggy, yet these days it has cooled down: still sunny, but no longer dizzyingly hot. It feels comfortable. More than five years of work pass before my eyes like a fast-forwarded film. I feel it is time to write down my experiences, thoughts, struggles, and choices. This is both an account of the past and a way to look toward the road ahead.
The idea of doing a PhD was never a sudden impulse. It was a seed planted in my student days. Back then, I was genuinely interested in research. I still remember a line from Andrej Karpathy’s “A Survival Guide to a PhD.” It felt like a beam of light. In a PhD, you may have five years to fully commit to one direction, become one of the people at the frontier, and push it forward with your own hands. That is a luxury, and perhaps a once-in-a-lifetime one.
“Luxury” is exactly the right word. In a world that is increasingly noisy and fragmented, having five uninterrupted years to focus deeply and purely on the boundary of a problem is itself a profound happiness. I longed for that luxury, for that feeling of moving through the wilderness of knowledge alone and with others, and for the excitement of intellectual collision with brilliant minds.
But practical realities always arrive before dreams. My family was financially poor. My parents had no pension and no medical insurance. They worked hard all their lives, and as their son I had the responsibility to provide at least a basic safety net for their old age. This responsibility was a non-negotiable constraint in my life. So between ideal and duty, I chose duty first. After graduation, I entered industry and folded the PhD dream away like a treasured white shirt, carefully placing it in the deepest corner of the closet. I told myself it was only temporary, and I would take it out when the time was right.
Searching in Reality: Finding My Objective Function
My first job was in high-frequency trading. By conventional standards, it was an excellent start: high technical bar, hard problems, and strong compensation. In the first months, I truly enjoyed solving technical challenges, and the intellectual satisfaction was real and intense. But over time, a deep sense of emptiness began to flood in.
I remember once working with a trader for two straight weeks on a core algorithm implementation. We were in the office almost every day until midnight. The whiteboard was packed with formulas and system diagrams, erased and redrawn again and again. In the end, we reduced strategy latency by 90%, a major technical breakthrough. The team celebrated briefly. But standing there, I felt strangely calm, even hollow.
Late that night, I walked out alone and stood on a bridge in Lujiazui. Lights glittered around me, traffic flowed below, and behind every window there seemed to be another busy soul like mine. I asked myself: what did all this change? Beyond making numbers move faster and capital games more extreme, did it make the world any better? I could not find an answer. It felt like forging an incredibly sharp weapon only to discover that its only purpose was to play a closed game irrelevant to most people. I kept asking: is this really the life I want?
This emptiness did not happen once. It seeped into my daily life. On morning commutes to Lujiazui, after late-night coding sessions, it showed up on schedule. The more successful the work, the stronger the feeling. I felt like a climber who reached a summit only to realize the view was never what he wanted. This mismatch between outward success and inner meaning was more exhausting than technical difficulty itself.
I began to realize I had become an efficient executor without a soul. My work did not resonate with my values. Painful as it was, this period was also a necessary calibration. It forced me to understand what I truly wanted: work that I personally find meaningful and that creates social value. I have a simple belief: if my work creates real value for society, then as a creator I will also receive corresponding returns, material or spiritual. If a job cannot satisfy my pursuit of meaning, then no matter how high the income, it becomes long-term internal friction.
So I described my life confusion with engineering language: my life’s objective function was wrong. No amount of local optimization can fix a mis-specified goal. I did not need to run faster on the wrong road. I needed to stop and find the road that truly belonged to me.
At that moment of confusion, a light came from afar. About a year after graduation, my close friend Xinjing, who had once discussed technology and dreams with me at Zhejiang University, was admitted to MIT for a PhD to pursue databases. I was sincerely happy for him, and I also felt a sharp, almost painful envy. His choice rang like a clear bell in my heart, reminding me that the white shirt in the closet was still clean and new. I told myself: I must walk that road too.
An Unexpected Rehearsal: Finding My Calling on the Podium
After leaving my first job, I got an accidental chance to return to Zhejiang University and teach machine learning for the Turing class for a period of time. At first I only wanted to fulfill my advisor’s request and fill a temporary gap. I never expected this “accident” to become a decisive turning point in my life.
That period remains unforgettable and exciting to this day. The first time I stood on the podium and saw dozens of clear, bright, eager eyes, I was struck by a completely new feeling. I was no longer a confused engineer. I became a transmitter of knowledge and a guide for thought. At that moment, it felt like the white shirt I had folded away floated back out of the closet and gently settled on my shoulders, carrying the smell of sunshine.
I spent enormous time preparing lectures. I almost gave up all social life, and immersed myself in syllabi and lectures from MIT, Stanford, CMU, and Berkeley. I wanted to offer these brilliant students a genuinely world-class course. In class, I did not just teach formulas and algorithms. I wanted to convey the joy of learning and the motivations behind ideas. I guided students to ask questions and encouraged critical thinking.
I remember once, while discussing spectral clustering, a student raised a hand and asked: “The min-cut problem seems very close to max-flow min-cut from algorithms. Can we just use that algorithm directly?” I paused for a few seconds and then felt a surge of joy. This was exactly what I most wanted to see: students actively building their own cross-disciplinary understanding, instead of passively receiving knowledge. Seeing confusion become clarity through explanation and dialogue brought me a deeper and more lasting joy than writing any efficient code ever had.
In the final class, I told them that I hoped this course had shown them that machine learning is both useful and interesting, and that learning can also be meaningful and joyful. I recited a passage from “Young China” and told them: in the small sense, many problems in machine learning and deep learning remain unsolved; in the large sense, this country and this society still have many unresolved problems. I believed some of them would solve part of those problems in the future, and create their own future. At the end, they gave me a long applause and came up for photos. Looking at their young and hopeful faces, I felt absolutely certain: this is what I want to do for life.
That experience also made me reflect on my own path. My family was poor. Without this country’s educational policies, I would never have had the chance to come this far or to improve my family’s life. Education is the most precious gift this country gave me. Now I want to pass that gift on. I resolved to contribute to computer science education in China, and to students from ordinary backgrounds who still carry great dreams, just like I once did.
At that moment, the PhD dream in the closet perfectly overlapped with a mission of serving education. It was no longer only a personal academic pursuit. It gained a larger and heavier meaning.
Tempered in Engineering: Forging Weapons for the Ideal
I knew this was what I wanted to do for life. But the path would be long. Ideals need the soil of reality. That white shirt representing the future had to be redeemed through concrete effort. I still needed to build financial security for my family, and I also needed to sharpen stronger tools for future academic work. With this renewed clarity, I joined DolphinDB. The following years became a period of rapid growth in my engineering capability.
I was very lucky to work in a technically pure and highly challenging environment, and to experience the full process of building a world-class software product from scratch. This was not a school assignment, nor tightening screws in a giant company. We faced real-world extreme performance requirements and complex scenarios. Those years were intense tempering, and what I learned went far beyond writing code.
In 2021, we started from zero to develop a new storage engine. Everything had to be built from scratch. Xinjing and I did extensive design research, read top papers from the past decade one by one, and debated repeatedly in front of a whiteboard, drawing version after version of architecture diagrams and stress-testing feasibility in theory. I still remember discussing one key memtable design for days: variants of LSM-Tree, applicability of B+Tree, and our own hybrid proposal. Every option was decomposed down to details, with prototypes and experiments used repeatedly to validate ideas.
Perfect plans in theory always meet surprises in practice. We had to write minimal prototypes for proof of concept. I still remember when we first implemented lock-free and zero-copy memtable and saw system throughput jump by an order of magnitude in testing. That pure engineer’s joy is hard to describe: turning theory into reality, and turning insight into performance.
I also started taking on the role of R&D lead, organizing team work and task assignment. More importantly, I stayed on the front line with everyone and kept coding. I believe only by going into implementation details can one truly understand a system’s strengths and weaknesses. We set extremely high quality standards, wrote large-scale tests, and built solid CI/CD pipelines to ensure every release was stable and reliable.
That full loop transformed my understanding of how to do engineering well. I am deeply grateful to my friend Xinjing, who introduced me and became my first mentor; to Davis, founder of DolphinDB, who is not only an outstanding CEO but also a top engineer still coding on the front line; and to Da Fei and every teammate who helped and guided me.
At DolphinDB, my work was recognized quickly and I became R&D lead in under four months. I could have stayed, waited for IPO, and obtained substantial financial rewards. During those days, I often felt a happy contradiction: on one hand, I enjoyed the pure joy of solving world-class engineering problems with excellent teammates; on the other hand, late at night, the classroom lights and students’ eyes would return vividly in my mind. That calling kept reminding me: all the tools I was forging here were for a more important battle in the future. The white shirt was still in the closet, waiting to be worn.
In fact, before joining, I had been open with Davis about my long-term plan. I told him I would definitely pursue a PhD in the future, and that one key reason for working here was to build financial security for my family first. He understood and respected that choice. Over these years, I never stopped preparing for PhD applications. I was fortunate to collaborate with Xinjing, Viktor Leis, Xiangyao Yu, and Mike Stonebraker, and publish a SIGMOD 2025 paper, which built a solid foundation for my application.
Decision Time: When Dreams Meet Reality
Time passed, and I reached my fourth year at DolphinDB. I calculated my savings and felt they were enough to provide my parents with a reassuring baseline for the future. The constraint that had once bound me was finally satisfied.
I knew it was time to open the closet and take out that long-preserved white shirt.
I began preparing PhD applications formally. Because of my undergraduate background (Northwestern Polytechnical University), US visa policy posed substantial uncertainty, so I had to focus on other countries. During this process, I once again felt the power of kindness and support. Viktor Leis, second author of our SIGMOD paper and professor at TUM, kindly introduced me to several top professors in Germany and Switzerland. Thanks to this, I entered their view and ultimately received offers. I remain deeply grateful for that cross-border support.
At first, Canada was not on my list. But my master’s advisors, Prof. Deng Cai and Prof. Xiaofei He, strongly encouraged me to consider North America. They believed it remained the center of computer science research, with the most active academic ecosystem. My mentor from my Google internship, Jingtao, also strongly recommended that I apply and gave me many practical suggestions. Encouraged by them, I submitted an application to the University of Toronto.
When all offers arrived, I had the pleasant difficulty of choosing. After in-depth conversations with several respected mentors, they almost unanimously recommended Toronto. During my PhD, I also wanted to explore innovation at the intersection of databases and AI, and Toronto unquestionably has world-class resources in that area. So I made my final choice. Later I reflected that where I do research may not matter that much in itself. Those schools all provide excellent environments. For me, being able to quietly do what I love and move toward my goal is enough.
When I told Davis I had decided to pursue the PhD, he was reluctant to lose me. But he told me something deeply moving: “Of course we hope you stay and go all the way to IPO with us. But your own path matters more, and we support your choice.”
Some Reflections Before Departure
Looking back at these five-plus winding years, I want to share a few reflections.
First, choosing what you truly love is profoundly important. For me, pursuing a PhD and taking the education path feels like an irresistible calling. I can only choose this; otherwise I would regret it for life. Some life choices are beyond cost-benefit calculation. When you hear a strong enough inner voice, you only need to listen and follow. Because of that, I believe this love can sustain me through whatever difficulties lie ahead. As Jobs said, “everything else is secondary.”
Second, in the AI era, if we use tools well, individual capability can be amplified in unprecedented ways. I am optimistic about the future. I believe these technologies can help create education models that are more efficient, fairer, and more inspiring. I hope to combine what I learned in academia and industry with AI to make practical contributions, however small, to computer science education in China.
Finally, I want to thank everyone who helped me along this path: my advisors, who gave both knowledge and direction at key moments; professors who wrote recommendation letters and trusted me; my friend Xinjing, both role model and fellow traveler; like-minded friends whose conversations constantly sharpened my thinking; my family, who silently bore my “stubbornness” and gave unconditional love; and the leaders and colleagues at DolphinDB, whose support and mentorship are invaluable assets for my future journey.
And the person I must thank most is my wife. When I described this difficult and unusual path and asked for her support, she gave me unwavering understanding and strength, allowing me to pursue my calling without looking back. I still remember telling her my favorite declaration of love was Premier Zhou Enlai’s line to his wife: “I hope we can devote ourselves to the revolution together, and one day walk to the guillotine together.” She understood instantly and held my hand tightly. She is my comrade on this journey.
My country, I will come back. Wait for me.