Guessing?

#41

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#42

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#43

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#44

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#45

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#46

Brian Selzer wrote:
....

Quote:

Well, that's just it. It has no consistent method for doing so. ...

It does, I gave one, ie., apply, ie., distribute algebraically, the
union to the base relations in the view expression, then apply whatever
constraints the definition has. Works just as consistently for deletes
to joins.

If it just

Quote:

guesses at the intent, 50% of the time it will guess wrong, and you'll end
up with garbage in the database. As a consequence, queries like, "How many
suppliers are west of the Mississippi?" will return the wrong answer.
...

My whole point is that the dbms has no business guessing, just following
orders. Why anybody would imagine a dumb pre-programmed logical machine
can know human intentions can only be pathological mysticism. As they
say, "don't believe everything you think".

Quote:

But again, it should not allow the update if it has to guess, because
inevitably, it will guess wrong at least some of the time and the database
will end up corrupt. That it has to guess is not a guess.
...

It is mysticism to think that a dbms that follows its own consistent
rules is somehow guessing.

#47

paul c wrote:

Quote:

Bob Badour wrote:

See POOD and the justifications for it. I think it safe to say at
least some relational proponents might agree with the comment about
mysticism or at least that Codd's opinion on the matter was not as
conclusive as he might have thought.

Would you say POOD is an upshot of the Information Principle?

I would say POOD is a direct response to the sorts of view updating
problems discussed in the book excerpt you omitted this time.

Quote:

Or is just a design approach Date and McGoveran came up with to work
around what they saw as an implementation problem?

It is a design principle for avoiding ambiguity in view updates.

Quote:

A corrolary of the IP might be that any contradictory information allows
contradictory results. If so, that wouldn't worry me. I'm
distinguishing here between information that we know versus the more
abstract information that the dbms has, given a particular design, I'd
say only what the dbms knows matters.

POOD is all about making sure the dbms knows what it needs to know. (Not
that I like anthropomorphizing dbmses.)

#48

paul c wrote:

Quote:

Bob Badour wrote:

See POOD and the justifications for it. I think it safe to say at
least some relational proponents might agree with the comment about
mysticism or at least that Codd's opinion on the matter was not as
conclusive as he might have thought.

Would you say POOD is an upshot of the Information Principle?

I would say POOD is a direct response to the sorts of view updating
problems discussed in the book excerpt you omitted this time.

Quote:

Or is just a design approach Date and McGoveran came up with to work
around what they saw as an implementation problem?

It is a design principle for avoiding ambiguity in view updates.

Quote:

A corrolary of the IP might be that any contradictory information allows
contradictory results. If so, that wouldn't worry me. I'm
distinguishing here between information that we know versus the more
abstract information that the dbms has, given a particular design, I'd
say only what the dbms knows matters.

POOD is all about making sure the dbms knows what it needs to know. (Not
that I like anthropomorphizing dbmses.)

#49

paul c wrote:

Quote:

Bob Badour wrote:

See POOD and the justifications for it. I think it safe to say at
least some relational proponents might agree with the comment about
mysticism or at least that Codd's opinion on the matter was not as
conclusive as he might have thought.

Would you say POOD is an upshot of the Information Principle?

I would say POOD is a direct response to the sorts of view updating
problems discussed in the book excerpt you omitted this time.

Quote:

Or is just a design approach Date and McGoveran came up with to work
around what they saw as an implementation problem?

It is a design principle for avoiding ambiguity in view updates.

Quote:

A corrolary of the IP might be that any contradictory information allows
contradictory results. If so, that wouldn't worry me. I'm
distinguishing here between information that we know versus the more
abstract information that the dbms has, given a particular design, I'd
say only what the dbms knows matters.

POOD is all about making sure the dbms knows what it needs to know. (Not
that I like anthropomorphizing dbmses.)

#50

paul c wrote:

Quote:

Bob Badour wrote:

See POOD and the justifications for it. I think it safe to say at
least some relational proponents might agree with the comment about
mysticism or at least that Codd's opinion on the matter was not as
conclusive as he might have thought.

Would you say POOD is an upshot of the Information Principle?

I would say POOD is a direct response to the sorts of view updating
problems discussed in the book excerpt you omitted this time.

Quote:

Or is just a design approach Date and McGoveran came up with to work
around what they saw as an implementation problem?

It is a design principle for avoiding ambiguity in view updates.

Quote:

A corrolary of the IP might be that any contradictory information allows
contradictory results. If so, that wouldn't worry me. I'm
distinguishing here between information that we know versus the more
abstract information that the dbms has, given a particular design, I'd
say only what the dbms knows matters.

POOD is all about making sure the dbms knows what it needs to know. (Not
that I like anthropomorphizing dbmses.)