Greg Stark escribió:
On Wed, Nov 25, 2009 at 1:03 AM, Konstantin Izmailov wrote:

My question: can pg_attribute.attnum be used to determine the sequential
ordinal positions of columns in a table? What is a right way to get the
ordinal numbers?
You could use something like:

row_number() over (partition by T.schemaname,T.viewname order by
attnum) as "ORDINAL_POSITION"
Should we recast the attributes and columns views in information_schema?
I notice they still use attnum.

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Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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  • Tom Lane at Dec 3, 2009 at 3:09 pm

    Alvaro Herrera writes:
    Should we recast the attributes and columns views in information_schema?
    I notice they still use attnum.
    I'd vote against it, at least until we have something better than a
    row_number solution. That would create another huge performance penalty
    on views that are already ungodly slow.

    When and if we get around to separating physical from logical column
    position, the issue might go away "for free".

    regards, tom lane
  • Peter Eisentraut at Dec 5, 2009 at 7:48 pm

    On tor, 2009-12-03 at 10:09 -0500, Tom Lane wrote:
    Alvaro Herrera <alvherre@commandprompt.com> writes:
    Should we recast the attributes and columns views in information_schema?
    I notice they still use attnum.
    I'd vote against it, at least until we have something better than a
    row_number solution. That would create another huge performance penalty
    on views that are already ungodly slow.
    Should be easy to test the performance impact of this, since the limit
    for columns per table is 1600.

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