Re^3: prepare statement within DBI


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Re^3: prepare statement within DBI

by mpeppler (Vicar)

on Aug 26, 2004 at 07:07 UTC ( [id://385926]=note: print w/replies, xml )

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in reply to Re^2: prepare statement within DBI
in thread prepare statement within DBI

A select count(*) usually has to traverse at least an index tree to find the actual number of rows currently in the table. A quick test on Sybase on a fairly busy server shows that it can take up to 3 seconds to count the rows in a 4+ million row table, with a lot of the time spent fetching data pages into cache. Keep in mind that the database engine has to be able to run the select count(*) where somecondition as well, for which no real short-cut is available, unless an appropriate index exists that can satisfy the WHERE clause.

Michael

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Re^4: prepare statement within DBI
by dragonchild (Archbishop) on Aug 26, 2004 at 12:06 UTC

select count(*) from table1;

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