Re: Key/Value reference table generation: INSERT/UPDATE performance

From: valgog <valgog(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Key/Value reference table generation: INSERT/UPDATE performance
Date: 2007-05-22 10:00:41
Message-ID: 1179828041.761272.152380@x35g2000prf.googlegroups.com
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I have rewritten the code like

existing_words_array := ARRAY( select word
from WORD_COUNTS
where word = ANY
( array_of_words ) );
not_existing_words_array := ARRAY( select distinct_word
from ( select distinct
(array_of_words)[s.index] as distinct_word
from
generate_series(1, array_upper( array_of_words, 1 ) ) as s(index)
) as distinct_words
where distinct_word <> ALL
( existing_words_array ) );
-- insert the missing words
if not_existing_words_array is not null then
insert into WORD_COUNTS
( word, count )
( select word, 1
from ( select
not_existing_words_array[s.index] as word
from generate_series( 1,
array_upper( not_existing_words_array, 1 ) ) as s(index) ) as
distinct_words
);
end if;
-- update the counts
if existing_words_array is not null then
update WORD_COUNTS
set count = COALESCE( count, 0 ) + 1
where sw_word = ANY ( existing_words_array );
end if;

Now it processes a million records in 14 seconds... so it was probably
the problem of looking up NOT IN WORD_COUNTS was way too expencive

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