Performance of Bit String
in [PgSql]
|
From: Andres Freund on 9 Jun 2010 12:59 Hi, Youre on the wrong list for this. This is not a -hackers (i.e. developer targeted) but a -general (user targeted) question. On Wednesday 09 June 2010 15:11:41 rupendra.chulyadyo(a)gmail.com wrote: > I tried to store a BitString of length 2 million in a Postgres table (see > code below), but it did not complete even in 3 mins and then I cancelled > it. Surprisingly, it only took few seconds when BitString was of length > 500K. Is there any restriction of length of BitString or am I missing > something here? I think youre missing that your algorithm for assembling the string has quadratic complexity. For each loop iteratoring the whole string will be newly allocated and then copied over. A faster way to create such a long string might be: SELECT array_to_string(array_agg(1),'')::bit(2000000) FROM generate_series(1, 2000000); Btw, your table definition has only the length bit(200k), but youre inserting bit(2000k)... What are you trying to achieve with such a long bitstring? Actually I cannot think of any database design where I would consider that a valid design- choice. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
|
Pages: 1 Prev: [HACKERS] Performance of Bit String Next: Out of date docs: DISABLE/ENABLE TRIGGER |