I have a postgresql table that has a column with data type = 'text' in which I need to create an index which involves this column being type casted to integer[]. However, whenever I try to do so, I get the following error:
ERROR: functions in index expression must be marked IMMUTABLE
Here is the code:
create table test (a integer[], b text);
insert into test values ('{10,20,30}','{40,50,60}');
CREATE INDEX index_test on test USING GIN (( b::integer[] ));
Note that one potential workaround is to create a function that is marked as IMMUTABLE that takes in a column value and performs the type casting within the function, but the problem (aside from adding overhead) is that I have many different 'target' array data types (EG: text[], int2[], int4[], etc...), and it would not be possible to create a separate function for each potential target array data type.
