Hi, I'm looking for a hint how array access performs in PostgreSQL in respect to performance. Normally I would expect access of a 1-dimensional Array at slot i (array[i]) to perform in constant time (random access).
Is this also true for postgres' arrays? May concrete example is a 1-dimensional array d of length <= 600 (which will grow at a rate of 1 entry/day) stored in a table's column. I need to access this array two times per tuple, i.e. d[a], d[b]. Therefore I hope access is not linear. Is this correct? Also I'm having some performance issues building this array. I'm doing this with a used-defined aggregate function, starting with an empty array and using array_append and some calculation for each new entry. I assume this involves some copying/memory allocation on each call, but I could not find the implementation of array_append in postgres-source/git. Is there an efficient way to append to an array? I could also start with a pre-initialized array of the required length, but this involves some complexity. Thank you Regards, Andreas -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
