Re: Best practice when reindexing in production

You could do something like this (which considers you use simple names for your indexes, where simple ~ [a-z_][a-z0-9_]*):

SELECT 
regexp_replace(i.indexdef, '^CREATE( UNIQUE)? INDEX (.*) ON (.*)', 'CREATE\1 INDEX CONCURRENTLY tmp_\2 ON \3;') || E'\n'
|| E'BEGIN;\n'
|| 'DROP INDEX ' || i.indexname || E';\n'
|| 'ALTER INDEX tmp_' || i.indexname || ' RENAME TO ' || i.indexname || E';\n'
|| E'COMMIT;\n'
FROM pg_indexes i
WHERE schemaname !~ '^(pg_|information_schema$)';

Although this one is *really simple* and *error phrone*, because it does not consider at least two things: index that are constraints and index that has FK depending on it. For the first case, you only need to change the constraint to use the index and the DROP command. As for the second case, you would need to remove the FKs, drop the old one and recreate the FK (inside a transaction, of course), but this could be really slow, a reindex for this case would be simpler and perhaps faster.

Regards,
-- 
Matheus de Oliveira
Analista de Banco de Dados
Dextra Sistemas - MPS.Br nível F!
www.dextra.com.br/postgres

I must be missing something here.
But, how is that FK depends on the index?
I understand FK lookup works much faster with the index supporting FK than without it, but you could have FK without index (on the "child" table).
So, what gives?

Regards,
Igor Neyman