| Lists: | pgsql-hackers |
|---|
| From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
|---|---|
| To: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | iterating over relation's attributes |
| Date: | 2007-05-05 17:09:31 |
| Message-ID: | 463CBA4B.9010206@dunslane.net |
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| Lists: | pgsql-hackers |
What is the approved way to iterate over a relation's attributes? I see
that lsyscache.c::get_relnatts() is marked NOT_USED and has been for
nearly seven years. Maybe it's time to remove that code ;-)
cheers
andrew
| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: iterating over relation's attributes |
| Date: | 2007-05-05 18:45:56 |
| Message-ID: | 25875.1178390756@sss.pgh.pa.us |
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Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> What is the approved way to iterate over a relation's attributes?
Most places scan through the relation's tuple descriptor, rather
than expending multiple catalog lookups in pg_attribute.
regards, tom lane
| From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: iterating over relation's attributes |
| Date: | 2007-05-05 20:00:05 |
| Message-ID: | 463CE245.7010700@dunslane.net |
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Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>
>> What is the approved way to iterate over a relation's attributes?
>>
>
> Most places scan through the relation's tuple descriptor, rather
> than expending multiple catalog lookups in pg_attribute.
>
>
>
Doesn't that require me to open the relation? Is that a good thing if I
wouldn't otherwise be doing that?
This is in the context of making CheckAttributeType recurse into
composite types.
cheers
andrew
| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: iterating over relation's attributes |
| Date: | 2007-05-06 00:13:35 |
| Message-ID: | 29387.1178410415@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> Tom Lane wrote:
>> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>>> What is the approved way to iterate over a relation's attributes?
>>
>> Most places scan through the relation's tuple descriptor, rather
>> than expending multiple catalog lookups in pg_attribute.
> Doesn't that require me to open the relation? Is that a good thing if I
> wouldn't otherwise be doing that?
Sure, because whatever work gets done is likely to be amortized across
multiple uses of the relcache entry anyway.
regards, tom lane