All:
Been looking at speed issues related to loading large data sets, and
experimenting with dropping and rebuilding indexes. I noticed some
interesting behavior on the table in question. Here's the table:
Table "test_responses_2"
Attribute | Type | Modifier
-------------------+-------------------+----------
id_response | integer |
id_code | integer |
id_survey | integer |
id_topic | integer |
id_item | integer |
id_administration | integer |
response_int | smallint |
response_txt | character varying |
rec_handle | character varying |
Indices: id_administration_test_key,
id_code_test_key,
id_item_test_key,
id_response_test_key,
id_survey_test_key,
id_topic_test_key
When I drop and rebuild the indexes, they take oddly varying amounts of time
to rebuild. I rebuilt them in the following order, with the following rough
times. I took a guess that the speed of the rebuild might be related to the
number of distinct values in the column -- this seems true in some cases but
not in others. Here are the times:
id_response 38 secs (86000 distinct)
id_topic 33 secs (6 distinct)
id_survey 13 secs (1 distinct)
id_code 39 secs (1444 distinct)
id_item 40 secs (65 distinct)
id_administration 13 secs (1 distinct)
Is there anything I should be learning from this?
-- sgl
=======================================================
Steve Lane
Vice President
The Moyer Group
14 North Peoria St Suite 2H
Chicago, IL 60607
Voice: (312) 433-2421 Email: [EMAIL PROTECTED]
Fax: (312) 850-3930 Web: http://www.moyergroup.com
=======================================================
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives?
http://archives.postgresql.org
