postgresql: Aggregating arrays of text -

i want array of words associated each id in example data:

id | words ---|------------------ 1  | {foo,bar,zap,bing} 2  | {foo} 1  | {bar,zap} 2  | {bing} 1  | {bing} 2  | {foo,bar}

outputs:

id | allwords ---|-------------------------------- 1  | {foo,bar,zap,bing,bar,zap,bing} 2  | {foo,bing,foo,bar}

i tried using array_agg(words) yields:

error: not find array type data type text[]

what's proper approach here? want words, duplicates.

array_agg collects results of column array; doesn't aggregate arrays.

array_cat functionality want, isn't aggregate function.

to define own aggregate based on it, use code:

create aggregate array_cat_aggregate (anyarray)  (     sfunc     = array_cat    ,stype     = anyarray    ,initcond  = '{}' );

which blatantly copied answer: https://stackoverflow.com/a/11763245/1394393. (i don't think question duplicate.)

pretending table called temp, can select using function group by:

select id, array_cat_aggregate(words) temp group id;

KHS