Brian Hirt wrote:
On Mar 13, 2011, at 12:05 PM, Dmitriy Igrishin wrote:

Hey Viktor,

2011/3/13 Viktor Nagy <viktor.n...@toolpart.hu <mailto:viktor.n...@toolpart.hu>>

    hi,

    when trying to insert a long-long value, I get the following error:

     index row size 3120 exceeds maximum 2712 for index
    "ir_translation_ltns"
    HINT:  Values larger than 1/3 of a buffer page cannot be indexed.
    Consider a function index of an MD5 hash of the value, or use
    full text indexing.

    is there a way to generate this recommended function index of an
    md5 hash on an already existing database and tables (filled with
    data)?

Just create index this way, e.g.
CREATE INDEX ir_translation_ltns ON tab ((md5(col)));
where "tab" and "col" are table and column of which you want
to create btree index.

This probably goes without saying, but you'll have to use col = md5('blahblahblahblah') in your qualifiers to get the benefit of the index.
--brian

Unless the point is to guarantee uniqueness of the "long-long value"s.


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