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Re: pg_sample

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On Tue, Oct 18, 2016 at 10:21 PM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:
On 10/18/2016 06:30 PM, Patrick B wrote:


2016-10-19 13:39 GMT+13:00 Michael Paquier <michael.paquier@xxxxxxxxx
<mailto:michael.paquier@gmail.com>>:

    On Wed, Oct 19, 2016 at 9:24 AM, Patrick B <patrickbakerbr@xxxxxxxxx
    <mailto:patrickbakerbr@gmail.com>> wrote:
    > However, this new database test server doesn't need to have all the data. I
    > would like to have only the first 100 rows(example) of each table in my
    > database.
    >
    > I'm using pg_sample to do that, but unfortunately it doesn't work well.
    > It doesn't get the first 100 rows. It gets random 100 rows.

    Why aren't 100 random rows enough to fulfill what you are looking for?
    What you are trying here is to test the server with some sample data,
    no? In this case, having the first 100 rows, or a set of random ones
    should not matter much (never tried pg_sample to be honest).
    --
    Michael



Actually it does matter because there is some essential data that has to
be in there so the code can work.

Well random does not know essential, it is after all random. If you want to test specific cases then you will need to build appropriate data sets.


--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx



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The following query should generate statements you can use to get the first 100 rows of every table.
You may need to tweak a bit as order is not guaranteed.

SELECT 'COPY ' || quote_ident(n.nspname) || '.' || quote_ident(c.relname)
    || ' TO '''
--    || 'C:\temp\'
    || '/tmp/'
    || quote_ident(n.nspname) || '_' || quote_ident(c.relname) || '.csv' || ''''
    || ' WITH CSV HEADER FORCE_QUOTE *;'
  FROM pg_class c
  JOIN pg_namespace n ON n.oid = c.relnamespace
 WHERE relkind = 'r'
   AND relname NOT LIKE 'pg_%'
   AND relname NOT LIKE 'sql_%'
   LIMIT 100;

--
Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.


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