Re: multiple inserts

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Msg-id 20050617154832.90325.qmail@web33314.mail.mud.yahoo.com
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Ответ на Re: multiple inserts  ("Oren Mazor" <oren.mazor@gmail.com>)
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Gren,

i'm not sure i fully understand why you would break up
the table.

it seems to me that breaking the table up would a
normalization thing vs a "i have a lot of inserts"
thing.

if you have repeating data in your 20 column table and
it can be normalized out, i'd go that route.  if all
your data is unique or can't be normalized, i'd stick
with the single table.

if there is some nuance i'm missing here, i would like
to learn it.


--- Oren Mazor <oren.mazor@gmail.com> wrote:

> hm. well. I'm looking at a data set that can
> potentially get a few
> thousand big. So I'll stick with the COPY command.
>
> the trick is that I'm inserting a 1000 row 20 column
> table. This gets
> super slow, as you can imagine, so I'm looking at
> creating a two tables, a
> 1000 row table with a single column (my unique
> identifiers) and a 20
> column table with a single row (the default values)
> and then UNIONing them.
>
> would doing a COPY be a better idea?
>
> On Fri, 17 Jun 2005 10:25:28 -0400, Tom Lane
> <tgl@sss.pgh.pa.us> wrote:
>
> > "Oren Mazor" <oren.mazor@gmail.com> writes:
> >> I'm wondering if it is at all possible to do a
> mass insert into a table
> >> using only a single query?
> >> Something along the lines of:
> >> insert into mytable values (val1), (val2), (val3)
> >
> > We should have that (it's in the SQL spec) but no
> one's gotten around to
> > it.  You could fake it with
> >
> >     insert into mytable
> >         select val1
> >         union all
> >         select val2
> >         union all
> >         ...
> >
> > But if you are thinking of really large amounts of
> data (like more than
> > a few dozen rows), you really want to use COPY
> instead.  Neither the
> > union approach nor the still-unwritten
> multi-insert would be likely to
> > be pleasant to use for thousands/millions of rows.
> >
> >             regards, tom lane
>
>
>
> --
> Nanny Ogg looked under her bed in case there was a
> man there. Well, you
> never knew your luck.
> (Lords and Ladies - Terry Pratchett)
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose
> an index scan if your
>       joining column's datatypes do not match
>




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