5 ms·

What does it mean that "tables with multiple columns aren't strictly necessary"? Do you use tables with 1 column?

by rambojazz 6y ago

nkozyra 6y ago
"One sequential primary key field is all the columns anyone will ever need in a database" - Bill Gates
- ethbr0 6y ago
  128 bits are enough for enumerating everything. - 2017
  - d110af5ccf 6y ago
    2^128 is ~10^38. For frame of reference, there are ~10^22 atoms in a penny and ~10^50 atoms in the entire planet. Alternatively, 585 years is "only" ~2^64 nanoseconds. 2^128 nanoseconds is on the order of 10^22 years, while the estimated current age of the universe comes in at a mere 10^10 years. What sort of enumeration could you possibly do in practice on such a scale? (Allocation, on the other hand, is an entirely separate problem.)
    - ethbr0 6y ago
      I can't think of any. But I think the historical lesson is that what I (nay, people much smarter than me) can think of today is insufficient for the greater tomorrow. The ridiculous historical quotes for computer counts, disk size, RAM were all predicated on people not computing differently. As it turns out, technology progressed, and people began doing entirely new, unexpected things with computing.
      - d110af5ccf 6y ago
        For the record, most (not all) of those quotes are taken somewhat out of context. Even in 1950, it was trivial to come up with examples of sets with more than (for example) 2^32 elements. When it comes to address space allocation (ie IPv6) I agree; I'm skeptical that 128 bits will prove to be sufficient. But as far as simple enumeration goes, 2^128 is unimaginably large and I don't see how changes in computing could possibly affect that assessment. An example. Partition a 2^128 address space evenly between 2^64 individual computers (it's difficult to imagine humanity ever possessing anywhere near this many devices). Each computer does nothing more than visit each value in its segment of the address space sequentially. No additional computations, nothing, just visits it. At 1 value per nanosecond (ie 1 GHz) this otherwise pointless exercise requires approximately 585 years to complete.
coolgeek 6y ago
I believe that they are referring to the EAV data model, which is maximally flexible, in terms of schema modification. But performance, especially in terms of queries (but also in terms of DML) is atrocious
d110af5ccf 6y ago
It means that everything a relational database is capable of (from CS theory) can be done with a single column of values per table. Note that each such table also has a "column" of primary keys; in other words, it's a simple K -> V mapping. Also note that just because you can do something doesn't mean that it will be efficient, or that it will be enjoyable to work with.
- dragonwriter 6y ago
  > It means that everything a relational database is capable of (from CS theory) can be done with a single column of values per table. Note that each such table also has a "column" of primary keys So, in other words, it's a two column table (“primary key” aren't some kind of virtual column, either in concrete databases or in relational theory.) Calling a database with two columns one of which is the primary key a one-column table is...just wrong.

What does it mean that "tables with multiple columns aren't strictly necessary"? Do you use tables with 1 column?

nkozyra 6y ago

"One sequential primary key field is all the columns anyone will ever need in a database" - Bill Gates

ethbr0 6y ago
128 bits are enough for enumerating everything. - 2017
- d110af5ccf 6y ago
  2^128 is ~10^38. For frame of reference, there are ~10^22 atoms in a penny and ~10^50 atoms in the entire planet. Alternatively, 585 years is "only" ~2^64 nanoseconds. 2^128 nanoseconds is on the order of 10^22 years, while the estimated current age of the universe comes in at a mere 10^10 years. What sort of enumeration could you possibly do in practice on such a scale? (Allocation, on the other hand, is an entirely separate problem.)
  - ethbr0 6y ago
    I can't think of any. But I think the historical lesson is that what I (nay, people much smarter than me) can think of today is insufficient for the greater tomorrow. The ridiculous historical quotes for computer counts, disk size, RAM were all predicated on people not computing differently. As it turns out, technology progressed, and people began doing entirely new, unexpected things with computing.
    - d110af5ccf 6y ago
      For the record, most (not all) of those quotes are taken somewhat out of context. Even in 1950, it was trivial to come up with examples of sets with more than (for example) 2^32 elements. When it comes to address space allocation (ie IPv6) I agree; I'm skeptical that 128 bits will prove to be sufficient. But as far as simple enumeration goes, 2^128 is unimaginably large and I don't see how changes in computing could possibly affect that assessment. An example. Partition a 2^128 address space evenly between 2^64 individual computers (it's difficult to imagine humanity ever possessing anywhere near this many devices). Each computer does nothing more than visit each value in its segment of the address space sequentially. No additional computations, nothing, just visits it. At 1 value per nanosecond (ie 1 GHz) this otherwise pointless exercise requires approximately 585 years to complete.

coolgeek 6y ago

I believe that they are referring to the EAV data model, which is maximally flexible, in terms of schema modification. But performance, especially in terms of queries (but also in terms of DML) is atrocious

d110af5ccf 6y ago

It means that everything a relational database is capable of (from CS theory) can be done with a single column of values per table. Note that each such table also has a "column" of primary keys; in other words, it's a simple K -> V mapping. Also note that just because you can do something doesn't mean that it will be efficient, or that it will be enjoyable to work with.

dragonwriter 6y ago
> It means that everything a relational database is capable of (from CS theory) can be done with a single column of values per table. Note that each such table also has a "column" of primary keys So, in other words, it's a two column table (“primary key” aren't some kind of virtual column, either in concrete databases or in relational theory.) Calling a database with two columns one of which is the primary key a one-column table is...just wrong.