Re: Table count option

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От Dave Page
Тема Re: Table count option
Дата
Msg-id 455B8CF1.2030400@postgresql.org
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Ответ на Table count option  ("Melvin Davidson" <mdavidson@cctus.com>)
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Melvin Davidson wrote:
> OK, one more time.
> 
> Yes I know that right click count does that!
> 
> I know about select count(*).
> I know about Right-click -> Count
> 
> The question was/is "What is the equivalent SQL function to update the
> Rows(counted) value?

Right, one more time :-)

There is no SQL function. It just does a SELECT count(*) and updates the 
value stored in memory (in the pgTable object to be precise).

> IOW, What is the underlying code in Right-click -> Count?

Ultimately, once you get clear of all the menu handling code you get to:

void pgTable::UpdateRows()
{    pgSet *props = ExecuteSet(wxT("SELECT count(*) AS rows FROM ONLY ") 
+ GetQuotedFullIdentifier());    if (props)    {        rows = props->GetLongLong(0);        delete props;
rowsCounted= true;    }
 
}

pgTable.rows contains the row count.
pgTable.rowsCounted is a flag that indicates that a count has been done, 
rather than an estimate made (estimates come from pg_class.reltuples, 
which is populated by ANALYZE).

Regards, Dave


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