A long time ago, in a galaxy far, far away, paul.serby@clockltd.com (Paul Serby) wrote:
> Why does 'select count(id) from "tblContacts"' do a sequential scan
> when the field 'id' is indexed using a btree? MySql simply looks at
> the index which is keeping a handy record of the number of rows.
> Can anybody explain how and why postgres does this query like it
> does?
Look into the semantics of MVCC (MultiVersion Concurrency Control);
that (otherwise useful) feature prevents having any such "handy
record."
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let name="cbbrowne" and tld="cbbrowne.com" in String.concat "@" [name;tld];;
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Developmental Psychology
"Schoolyard behavior resembles adult primate behavior because "Ontogeny
Recapitulates Phylogeny" doesn't stop at birth."
-- Mark Miller