jchen5

When we talk about how SingleStore unifies transactions and analytics into a single database, and how fast it is at both, people understandably find it hard to believe at first - most database systems today do one or the other well, but not both.

Here are numbers to back up our claims, on the industry-standard benchmarks TPC-H (analytics) and TPC-C (transactions). SingleStore delivers state-of-the-art performance on both, compared to leading cloud data warehouses and a leading cloud operational database - SingleStore matches the data warehouses on TPC-H and matches the operational dbs on TPC-C, and does it with excellent scale-out performance in the cloud. On the other hand, the data warehouses couldn't even run TPC-C, and the operational database didn't finish TPC-H within 24 hours.

Not every workload needs the full spectrum of transactions and analytics, but modern applications increasingly need at least some of both. We think SingleStore is the general-purpose database system of the future, capable of running a breadth of workloads and unifying multiple disparate domain-specific database systems into one.

Check out the results at https://www.singlestore.com/blog/tpc-benchmarking-results/ and if you're interested, try out SingleStore for yourself - we published the benchmark materials in our github repo https://github.com/memsql/benchmarks-tpc

The data says a lot of people have mild/moderate visual visual artifacts (halos, starbursts, etc.) and dry eye prior to getting lasik. Lasik appears to make some of those symptoms disappear in many people, but also causes symptoms to appear in a smaller number of people.

E.g. for dry eye, from PROWL-1 [2], table 2: before: 45% any severity, 6% severe; after 6 months: 27% any severity, 3% severe; and those changes included 19.5% of those without symptoms developing new symptoms and 65% of those with prior symptoms seeing those resolve.

But it's really hard to interpret the data because a surprisingly large fraction of people report changes (both no symptoms to symptoms and vice versa) over some period of time without having lasik at all! ("14% (95% CI, 3%-35%) to 29% (95% CI, 13%-49%) of participants answered that they either did or did not have a symptom on the test and vice versa on the retest")

See my comment [1] for more.

[1] https://news.ycombinator.com/item?id=21547710

[2] https://jamanetwork.com/journals/jamaophthalmology/fullartic...

I have been looking through the literature on lasik complications since I am considering lasik and there were several articles recently such as [1] which goes into a lot more detail. There are a lot of temporary complications/side effects (e.g. a few months), but what I'm most interested in understanding is the risk of lasik causing serious, long-lasting or permanent complications. The main ones discussed in these articles are visual artifacts (halos, starbursts, etc.) and dry eye (which at the extreme end means constant intense pain).

Unfortunately, as far as I could tell, there aren't very good studies on the topic - they're very limited in number of people and in length of time studied, or they don't measure a control group/baseline - which is a big problem because there is a surprisingly high prevalence of symptoms in the population even before lasik. This makes the data very hard to interpret.

E.g. [1] reports that 6 months after surgery, "41 percent of patients reported visual aberrations, with nearly 2 percent saying the symptoms presented 'a lot of difficulty' or 'so much difficulty that I can no longer do some of my usual activities.' But looking at the data from the PROWL-1 and PROWL-2 studies [2], table 3, 67% of patients had some visual symptom _before_ lasik surgery, with 3.3% / 7.5% having difficulty performing activities and 10.8% / 13.3% reporting "very" or "extremely" bothersome symptoms (again, before lasik). The prevalence of severe visual symptoms decreases 6 months after lasik. However, while some people go from severe symptoms to no symptoms, some of that is just due to regression to the mean (see note on test-retest in [2]), and there is also a substantial percentage of the population that goes from no symptoms to having some symptoms (which is the main thing I am trying to estimate).

Surveying some of the other literature [2][3][4], the overall pattern I saw was that pre-lasik the prevalence of dry eye and visual symptoms is about 60% of any severity, 5% severe, 5-10% moderate. Post-lasik they are about 50% any severity, 3% severe, 5% moderate. Overall they are less postop - but the question is how many people who were normal preop develop symptoms postop (minus how many people who were normal develop symptoms 6 months later without any lasik surgery). I haven't found good enough data to answer this with any degree of accuracy, other than an upper bound of <1% developing severe symptoms and <5% developing moderate symptoms. That isn't a very helpful upper bound to me - a 1% chance of permanent severe complications is a lot, and I think it's obvious that if the rate were that high we'd know about it. But from the data it appears plausible that the rate of developing long-lasting moderate complications is 0.1% - 1%, and the high end of that range is still a pretty substantial rate of complications. I think the actual rates are a lot lower, we just don't seem to have enough data to measure it better. I would love to see pointers to better studies, better analyses of the data, etc.

[1] https://www.nytimes.com/2018/06/11/well/lasik-complications-...

[2] https://jamanetwork.com/journals/jamaophthalmology/fullartic...

[3] https://www.ncbi.nlm.nih.gov/pubmed/25896684

[4] https://www.ncbi.nlm.nih.gov/pubmed/27373395

If you just use the no-frills SQL query, we're able to optimize it to do a fast index seek (instead of scan) on q.time, because we know we only have to get the max row. This optimization isn't specific to proximate joins, a simple query like: select max(a) from t where a < 42; will be optimized by memsql.