Re: what is the PostgreSQL idiom for "insert or update"?

On Wed, Mar 16, 2011 at 07:32:13AM -0700, Robert Poor wrote:
> In my application, I receive large blocks of external data that needs
> to be extracted / translated / loaded into the db, and many of these
> data are duplicates of what's already there.
>
> Consequently, I would like to do efficient "bulk loading" of tables
> using multi-row INSERT commands, ignoring unique records that are
> already present, where 'uniqueness' is defined by key constraints.
>
> F'rinstance, assume:
>
> CREATE TABLE "weather_observations" ("id" serial primary key,
> "station_id" integer, "observation_time" timestamp, "temperature_c"
> float)
> CREATE UNIQUE INDEX "observation_index" ON "weather_observations"
> ("station_id", "observation_time")
>
> Now I'd like to be able to do multi-row inserts, but ignoring
> duplicate entries (specifically, those that would violate uniqueness
> constraint of the index):
>
> INSERT INTO weather (station_id, date, temperature) VALUES
>   (2257, '2001-01-01', 22.5),
>   (2257, '2001-01-02', 25.3);
>
> INSERT INTO weather (station_id, date, temperature) VALUES
>   (2257, '2001-01-02', 25.5),                 -- ignored: record already present
>   (2257, '2001-01-03', 21.0);
>
> What's the idiom for doing this in PostgreSQL?
>
> [As an aside, in SQLite, you can modify an INSERT statement with "OR
> IGNORE" to achieve this.]
>
> Thanks!
>

Here is the current documented method:

http://www.postgresql.org/docs/9.0/static/plpgsql-control-structures.html

Regards,
Ken