Hi I have come across a weird issue with truncation of text in an array (in this case using pg_indexes view) This query truncates the second array element at 63 characters SELECT ARRAY[indexname,indexdef] FROM pg_indexes However reversing the order doesn't truncate SELECT ARRAY[indexdef,indexname] FROM pg_indexes Anyone know why this behaviour occurs? thanks Mike |
It's likely related to the following: The system uses no more than NAMEDATALEN-1 bytes of an identifier; longer names can be written in commands, but they will be truncated. By default, NAMEDATALEN is 64 so the maximum identifier length is 63 bytes. David J. |
In reply to this post by Mike Martin
Mike Martin <[hidden email]> writes:
> I have come across a weird issue with truncation of text in an array (in > this case using pg_indexes view) > This query truncates the second array element at 63 characters > SELECT ARRAY[indexname,indexdef] FROM pg_indexes > However reversing the order doesn't truncate > SELECT ARRAY[indexdef,indexname] FROM pg_indexes > Anyone know why this behaviour occurs? indexname is of type name, indexdef is of type text, and the rules for inferring the type of an array[] construct are such that the first element's type wins in these cases. regression=# SELECT pg_typeof(ARRAY[indexname,indexdef]) FROM pg_indexes limit 1; pg_typeof ----------- name[] (1 row) regression=# SELECT pg_typeof(ARRAY[indexdef,indexname]) FROM pg_indexes limit 1; pg_typeof ----------- text[] (1 row) You could insert an explicit cast to text to avoid the truncation of indexdef to name: regression=# SELECT pg_typeof(ARRAY[indexname::text,indexdef]) FROM pg_indexes limit 1; pg_typeof ----------- text[] (1 row) The documentation about that is here: https://www.postgresql.org/docs/current/typeconv-union-case.html although looking at this example it seems like that description isn't telling the full truth. regards, tom lane |
Thanks! Possibly the use of name type in pg_tables could be emphasized and maybe a note about name type in docs somewhere On Sun, 16 Aug 2020, 18:12 Tom Lane, <[hidden email]> wrote: Mike Martin <[hidden email]> writes: |
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