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Document that COUNT(*) might not need a seq scan any more.

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Noted by Josh Kupershmidt.
This commit is contained in:
Robert Haas 2012-01-27 12:40:37 -05:00
parent db6de5b71e
commit eb6af016fc
1 changed files with 4 additions and 2 deletions
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doc/src/sgml/func.sgml
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@ -11102,8 +11102,10 @@ SELECT b1 = ANY((SELECT b2 FROM t2 ...)) FROM t1 ...;
<programlisting>
SELECT count(*) FROM sometable;
</programlisting>
will be executed by <productname>PostgreSQL</productname> using a
sequential scan of the entire table.
will require effort proportional to the size of the table:
<productname>PostgreSQL</productname> will need to scan either the
entire table or the entirety of an index which includes all rows in
the table.
</para>
</note>