Re: How much clustered? - Mailing list pgsql-general

From Tom Lane
Subject Re: How much clustered?
Date
Msg-id 28416.1140104260@sss.pgh.pa.us
Whole thread Raw
In response to How much clustered?  (Carlos Henrique Reimer <carlosreimer@yahoo.com.br>)
Responses Re: How much clustered?  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-general
Carlos Henrique Reimer <carlosreimer@yahoo.com.br> writes:
>   I would like to know how much clustered is a table related to some index.... How can I discover?

You could do
    select ctid from mytable order by indexcolumns
and then do whatever sort of calculation strikes your fancy on the
sequence of page numbers.  (It's probably fair to ignore the row
numbers, considering an index to be fully clustered if the page
reference sequence is perfect.)

            regards, tom lane

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