Hi,
Josh Berkus writes:
>> The stumbling block has been to identify a reasonably clean way
>> of determining which datatype changes don't require a scan.
>
> Yep. One possibility I'm thinking is supplying a function for each type
> which takes two typemods (old and new) and returns a value (none
Josh Berkus writes:
>> Yeah, this has been discussed before; I think it's even in the TODO
>> list.
> I couldn't find it. At least, not under data types, and also not with
> the keyword "typemod". Anyone see it?
It's the last item under ALTER:
* Don't require table rewrite on ALTER TABLE ...
Josh Berkus writes:
> yeah, you're right .. that would give us a short list of conversions
> which don't require a rewrite.However, as Tom points out, that
> doesn't mean that they might not need a reindex (as well as OID, there's
> also XML).
Um. I had actually forgotten about the reinde
Jeff,
I observe that the casts (VARCHAR -> TEXT and TEXT -> VARCHAR) are
marked WITHOUT FUNCTION. If that's the case, can't we use that to say
that no heap rebuild is required? Perhaps we'll need to combine this
with the typmod checks to see if we need to check the heap.
yeah, you're right .
On Mon, 2009-06-01 at 14:39 -0700, Josh Berkus wrote:
> Note that this doesn't deal with the special case of VARCHAR-->TEXT, but
> just with changing typemods. Are there other cases of data *type*
> conversions where no check or rebuild is required? Otherwise we might
> just special case VARCH
Yeah, this has been discussed before; I think it's even in the TODO
list.
I couldn't find it. At least, not under data types, and also not with
the keyword "typemod". Anyone see it?
The stumbling block has been to identify a reasonably clean way
of determining which datatype changes don'
On Mon, Jun 1, 2009 at 10:40 PM, Tom Lane wrote:
> We could certainly put in a quick hack that just covered a few of the
> cases for built-in types, but it's not very pleasing ...
Jonah proposed a patch for that a long time ago.
See http://archives.postgresql.org/pgsql-patches/2006-10/msg00154.p
On Mon, 2009-06-01 at 13:26 -0700, Josh Berkus wrote:
> All,
>
> I just realized that even if you do this:
>
> table foo (
> id serial,
> bar varchar(200)
> )
>
> ALTER TABLE foo ALTER COLUMN bar TYPE VARCHAR(1000)
>
> ... it triggers a heap & index rebuild, even though it'
Josh Berkus writes:
> I just realized that even if you do this:
> ALTER TABLE foo ALTER COLUMN bar TYPE VARCHAR(1000)
> ... it triggers a heap & index rebuild, even though it's completely
> unnecessary.
Yeah, this has been discussed before; I think it's even in the TODO
list. The stumbling bloc
All,
I just realized that even if you do this:
table foo (
id serial,
bar varchar(200)
)
ALTER TABLE foo ALTER COLUMN bar TYPE VARCHAR(1000)
... it triggers a heap & index rebuild, even though it's completely
unnecessary. Is this a special case of VARCHAR, or are the
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