insert only unique values in to a table, ignore rest?

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От George Nychis
Тема insert only unique values in to a table, ignore rest?
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Msg-id 45A2B070.9090601@cmu.edu
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Ответы Re: insert only unique values in to a table, ignore rest?  (Scott Marlowe <smarlowe@g2switchworks.com>)
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Hi,

I have approximately 2 billion data entries that I would like to insert into a database.
Each entry consists of:
INT BOOLEAN INT BOOLEAN

I want to populate a table such that it only contains the unique rows, all other data
should be thrown out.  I would say a significant amount of the insertions are going to
fail due to unique constraints.  The unique constraint is on the two integers, not on the
booleans.

Using mysql, I was able to do this with the following query, for all data files (25574
data files total):
mysql -e \"use connectivity; LOAD DATA INFILE '/path/to/file' IGNORE INTO TABLE ipconn
FIELDS TERMINATED BY ' ';\"

What I *think* mysql did was sort each data file and do a sort of merge sort between the
data I was inserting and the data in the database.  It would insert the first unique
instance of a row it saw, and reject all other insertions that violated the unique
constraint due to the "IGNORE".

From what I understand, this functionality is not in postgresql.  Fine, I certainly can't
change that.  But I am looking for a comparable solution for the size of my data.

One solution is to have a temporary table, insert all 2 billion rows, and then copy the
distinct entries to another table.  This would be like one massive sort?

Is this the only/best solution using postgresql?

Thanks!
George

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