[HN Gopher] eBay's Fast Billion-Scale Vector Similarity Engine
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       eBay's Fast Billion-Scale Vector Similarity Engine
        
       Author : jabo
       Score  : 30 points
       Date   : 2023-05-05 20:56 UTC (2 hours ago)
        
 (HTM) web link (tech.ebayinc.com)
 (TXT) w3m dump (tech.ebayinc.com)
        
       | Scoundreller wrote:
       | Nice to see eBay invest further on its search side.
       | 
       | This paper is too dense for me to read through at this moment,
       | but eBay must be a real disappointment for its shareholders:
       | 
       | Despite its head start at being a platform for online retail open
       | to anyone, eBay stock has only doubled in 10 years, or in other
       | words, added $12b in equity value (currently $24b). Imagine that:
       | a successful tech company with a real product in a market that's
       | going stratospheric (online shopping) has lagged the S&P 500.
       | 
       | Meanwhile Amazon has octupled, which works out to adding $864b in
       | market value.
       | 
       | In other words, Amazon has added 36 eBays worth of equity to
       | itself in the last 10 years.
       | 
       | Ok, I haven't looked at corp debt to calculate these numbers
       | based on enterprise value, but that could make the numbers worse:
       | eBay is asset-light with little physical infra compared to
       | Amazon.
       | 
       | eBay's fees have gone through the roof, so I suspect its volume
       | has been decreasing.
        
         | sashank_1509 wrote:
         | Amazons growth has been one of the most astonishing things this
         | decade. It feels like they broke all rules and managed to
         | absolutely dominate. I remember in the 2000s the dominant
         | paradigm was to be a platform since software "can't do infra".
         | The idea was to be the middleman that Walmart, Target etc use,
         | not to directly compete with them. Amazon did the opposite and
         | competed hard and won.
         | 
         | Another anecdote is in a sea of tech companies that try to
         | attract talent with perks/ benefit/ even high salaries Amazon
         | had none. Amazon prides itself for making a table out of a door
         | to save money (no joke). But arguably Amazon employees made
         | bank in Amazon because of its stock growth, definitely more
         | compared to Google, Apple, Meta, maybe similar to Microsoft.
         | Finally of all companies, Amazon is the only big tech I know
         | that veered off its main product and still dominated. AWS is
         | completely off the left field for Amazon, it makes me
         | optimistic that Amazon might become a juggernaut in healthcare
         | too (they definitely are trying).
        
         | cjbgkagh wrote:
         | Ebay used to have an engineering limit on the number of items
         | in their indexes so they couldn't grow and had to increase fees
         | instead to keep the item count down, I don't know if they still
         | have that limit, I haven't been paying attention. It meant they
         | ended up with a focus on very high margin crap, Amazon is now
         | going the same way because they can and it makes a lot of
         | money.
         | 
         | Maybe with more listings eBay can lower their fees so that low
         | margin items are able to be sold. And maybe with some
         | competition between the two there might be a reduction of fees
         | and a return to quality. Sadly I don't think eBay is competing
         | effectively, their website still sucks and I can't get anything
         | resembling an invoice for taxes, maybe it's there but I haven't
         | seen it, I don't use eBay very often.
        
           | MontyCarloHall wrote:
           | >Ebay used to have an engineering limit on the number of
           | items in their indexes so they couldn't grow and had to
           | increase fees instead to keep the item count down
           | 
           | I find this incredibly hard to believe. The hard limit on the
           | number of total listings was deemed such an intractable
           | problem to solve that rather than focus all engineering
           | efforts for a few months on raising it, they just threw up
           | their hands, didn't even attempt to solve it, and tried to
           | increase revenue solely through higher listing fees?
        
             | bliteben wrote:
             | I find it very credible. Early ebay had very high fees on
             | photos. They also would purge old auctions within at least
             | 90 days. They still do purge old auctions which clearly
             | would have some seo value. Also the whole way ebay motors
             | was operated as essentially a separate site lends
             | credibility as well.
        
               | MontyCarloHall wrote:
               | That just means they were trying to cut costs (by
               | reducing their storage footprint) and raise revenue (by
               | charging a premium for photos) at the same time. I guess
               | the brass at eBay deemed the commercial value of
               | archiving old listings to be worth less than the cost of
               | storing them. Remember, storage used to be very
               | expensive, and no amount of engineering effort could
               | decrease the cost of server racks and hard drives.
               | 
               | eBay motors is separate because the process of buying a
               | car is very different from buying knickknacks. The number
               | of listings on eBay motors is tiny compared to the main
               | site, so it doesn't even make sense that they'd split it
               | off specifically to split up their listing database.
               | 
               | None of what you mention is evidence of a technical
               | limitation.
        
       | esafak wrote:
       | HNSW seems better in the criteria that matter.
       | 
       | I think similarity search is a commodity now; I would not invest
       | in developing an in-house solution given the abundance of good
       | commercial solutions.
        
         | cjbgkagh wrote:
         | They're embeddings so they're dense. There are few things
         | easier than dense vector similarity.
        
           | esafak wrote:
           | Embeddings for retrieval don't have to be. It is not unheard
           | of to transform the raw embeddings to optimize them for
           | retrieval; e.g., through binarization or hashing.
        
             | cjbgkagh wrote:
             | I was more making a distinction between embeddings and bag
             | of words which are very very sparse matrices. The embedding
             | dimensionality will not be anywhere near as high so this
             | level of sparsity is a minor inconvenience.
             | 
             | Edit: also CPUs for this, yikes...
        
       | almog wrote:
       | One of the best things about eBay compared to other market places
       | like Amazon and Aliexpress, is that their search operators
       | include not just AND (space) but also OR (comma separated values
       | inside parentheses) and NOT (minus) but more importantly - eBay's
       | search engine respects the supported operators and denoting which
       | items are search results and which are suggested/similar.
       | 
       | This cannot be said about Amazon, Aliexpress, both which
       | intentionally (I guess) mix similar items with results that match
       | the search query.
       | 
       | I hope that eBay keep those two things distinct.
        
         | Duplo wrote:
         | I dislike eBay search, for example all of a sudden one of my
         | daily bookmarked searches went from the usual 10 results to
         | THOUSANDS, all of them not including my search term, this is
         | the link:
         | https://www.ebay.co.uk/sch/i.html?_nkw=Tasmota&LH_PrefLoc=1&...
         | 
         | Why are some sellers having all their listings (car parts)
         | included in my search for "Tasmota"?
        
           | almog wrote:
           | That's interesting, I've seen it happening randomly that a
           | search query would return unrelated results for 1 out of 100
           | queries using the same query.
           | 
           | In your example however, it seems to me that if you add
           | quotes, the irrelevant results are gone:
           | https://www.ebay.co.uk/sch/i.html?_nkw=%22Tasmota%22
        
         | Scoundreller wrote:
         | _And_ you can setup email alerts for those complex search
         | terms.
         | 
         | I made a tiny amount of money doing typo arbitrage on bundles
         | labelled as "Nitendo" many years ago.
         | 
         | Sometimes when I wanted a really niche item, I'd wait for one
         | of those alert emails that had more than usual results because
         | I knew the bidding would be split.
        
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