Re[2]: [HACKERS] psql \d command

Hello Jan,

giovedì, 22 ottobre 98, you wrote:

>>
>> Hi all,
>>
>> I see now \d shows indexes, I tried to display index structure but it
>> show the wrong
>> length of fields:
>>
>> [...]
>>
>> hygea=> \d figure_pkey
>>
>> Table = figure_pkey
>> +----------------------------------+----------------------------------+-------+
>> | Field | Type |
>> Length|
>> +----------------------------------+----------------------------------+-------+
>> it should be:
>> | azienda | char()
>> | -4 |<<-- 11
>> | tipo | char()
>> | -4 |<<-- 02
>> | gruppo | char()
>> | -4 |<<-- 02
>> | inizio_attivita | date
>> | 4 |<<-- 04
>> +----------------------------------+----------------------------------+-------+

JW> The atttypmod value off all index attributes is 0 in
JW> pg_attribute. That's the reason why \d shows this. This
JW> information is not required for indices because the datum
JW> given to the index access methods comes from the heap tuples
JW> and it must already have the correct size if it reaches
JW> there.

JW> For data types of variable size, an atttypmod value of -1
JW> means variable, a value of n means size = n-4 (4 is the size
JW> of the variable length datum header VARHDRSZ). Don't worry,
JW> you cannot select from an index directly, so it doesn't
JW> matter. But psql might get enhanced for 6.5 to lookup the
JW> atttypmod of the indexed field in the table instead of using
JW> that from the index.

I'm not worry, only a aesthetical question. Thanks for reply.