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How many columns can I have in an ORDER BY clause?

From: Mary Anderson <maryfran(at)demog(dot)berkeley(dot)edu>
To: pgsql-novice(at)postgresql(dot)org
Subject: How many columns can I have in an ORDER BY clause?
Date: 2010-02-26 01:11:41
Message-ID: 4B871FCD.5000605@demog.berkeley.edu (view raw or flat)
Thread:
Lists: pgsql-novice
Hi,

     I have a query that has an ORDER BY clause that appears to break.
It has 12 or 13 columns.  Have I exceeded postgresql's sorting capacity?

Here is my query:
  BIG_SELECT_cmd = SELECT
 
value,x.d15_dv_id,x.d5_dv_id,x.dm1_dv_id,x.dm2_dv_id,x.d8_dv_id,x.d12_dv_id,v.data_batch_id

  FROM display.perm_tmp_xprod_table_550 x LEFT JOIN
  display.perm_tmp_data_values_550 v
  ON x.d15_dv_id = v.d15_dv_id
  AND x.d5_dv_id = v.d5_dv_id
  AND x.dm1_dv_id = v.dm1_dv_id
AND x.dm2_dv_id v.dm2_dv_id
AND x.d8_dv_id = v.d8_dv_id
AND x.d12_dv_id =v.d12_dv_id

ORDER BY
x.d15_group_order,x.d15_value_rank,
x.d5_group_order,x.d5_value_rank,
x.dm1_group_order,x.dm1_value_rank,
x.dm2_group_order,x.dm2_value_rank,
x.d8_group_order,x.d8_value_rank,
x.d12_group_order,x.d12_value_rank,
v.DMEM_status,
'2050-01-01'::DATE - v.data_batch_created_date

I checked the underlying tables.  They seem to be reasonable -- no nulls
But the dm1 values and the dm2 values do not sort at all.

Mary

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Next:From: Tom LaneDate: 2010-02-26 01:29:52
Subject: Re: How many columns can I have in an ORDER BY clause?
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Subject: Re: Importing lines of variable length from ASCII

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