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Re: Enumerating a row set

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On Thu, Mar 26, 2009 at 06:42:45PM -0400, George Sakkis wrote:
> Hi all,
> 
> Is there a function similiar to Python's enumerate() [1] ? Searching
> the docs didn't reveal any relevant builtin but I hope it's doable in
> pgsql. Ideally I'd like a function that can be used as:
> 
> SELECT e.i, e.col1, e.col2
> FROM enumerate(some_table, 'i') e
> LIMIT 10

In PostgreSQL 8.4, you'll be able to do:

SELECT
    row_number() OVER (ORDER BY col1) AS i,
    e.col1,
    e.col2,
    ...
FROM ...

Until then, there are some ugly, fragile workarounds with
generate_series() and/or temp sequences.

Cheers,
David.
> 
> i   col1  col2
> =========
> 0   ...     ...
> 1   ...     ...
> ...   ...     ...
> 9   ...     ...
> 
> Also ideally it should work on any rowset (e.g. nested select), not
> just on concrete tables.
> 
> Thanks in advance,
> George
> 
> [1] http://docs.python.org/library/functions.html#enumerate
> 
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