
Is Google lying about total number of results? - zabi_rauf
https://www.useloom.com/share/0a12b65af22a48ad84eac2a02119b3e7
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trumped
Yes. Often they initially claim that there is many thousands of results but
when you get to page 5, it now claims that there is only 47 results (for
example).

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Arnt
Do you also consider it a lie when postgresql's planner starts a query by
assuming that it'll deliver thousands of rows, but once it's run the query to
completion there are only 47?

Postgresql does that because the initial number is based on samples and
statistics and heuristics, and is produced by the query planner as a side
effect of making the query execution plan. I imagine Google, too, has a query
planner.

~~~
trumped
I agree with you but from my experience, the total number of results if almost
definitely inflated... either that or it is completely meaningless. (ie: about
the only time that the result count is not inflated is when there are 0
results and I have never seen them underestimate)

~~~
Arnt
There's a good reason to expect that it usually will be an oversestimate. Two
reasons actually.

One, google has a strong incentive to avoid underestimates: Underestimates
have a fairly high risk of causing RAM/CPU problems since the actual work that
must be needed is higher than estimated, and that's an evil ugly problem when
processing input from potentially malevolent anonymous users on the net.

Two, the simplest algorithm to compute the estimate is one that'll
overestimate if you choose a good combination of search terms, such as two
words that hardly ever occur together. The planner's statistics will know how
common each search term is, but may not know that this particular combination
is very rare.

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Amelia_s
no, I don't think so. researches are following algorithms no matter what the
word searched is but some results might be excluded form the search according
to some specific settings.

