create table like behaviour

[Sushanth Sowmyan <kh...@gmail.com>]

Hi All,

Currently, if I do the following:

hive -e 'create table a(k1 string, k2 int) TBLPROPERTIES("pi" = "3.14159")'
hive -e 'create table b like a;'
hive -e 'describe extended a;'
hive -e 'describe extended b;'


We see that the table property is not copied over to the definition of
b. Does anyone know if this is by design (i.e. by a principle that
table properties are not table description and so should not be copied
over) or is it a bug? I also notice that there's HIVE-3527, which
added the ability to create TBLPROPERTIES on the table being created,
so I assume it's by design, but I wanted to check if anyone knew/had
strong feelings about it.

I can see a good reason for not copying over tableproperties if
they're used to store specific table state (say backup state/etc), but
I also see a good reason for copying over table properties, with
things like orc, which store table metadata of sorts(like
orc.compress, or stride size, etc) in table properties, which makes a
good case for copying them over  if a person wants to create a table
with similar definitions to the first.

-Sushanth

Re: create table like behaviour

[Thejas Nair <th...@hortonworks.com>]

I think it is intuitive that all metadata gets copied over, for 'create
table like'.  I would treat the case of TBLPROPERTIES that should not be
copied over as a very special case, a case in which the user should be able
to remove the property.


On Thu, Mar 13, 2014 at 3:15 PM, Sushanth Sowmyan <kh...@gmail.com>wrote:

> Hi All,
>
> Currently, if I do the following:
>
> hive -e 'create table a(k1 string, k2 int) TBLPROPERTIES("pi" = "3.14159")'
> hive -e 'create table b like a;'
> hive -e 'describe extended a;'
> hive -e 'describe extended b;'
>
>
> We see that the table property is not copied over to the definition of
> b. Does anyone know if this is by design (i.e. by a principle that
> table properties are not table description and so should not be copied
> over) or is it a bug? I also notice that there's HIVE-3527, which
> added the ability to create TBLPROPERTIES on the table being created,
> so I assume it's by design, but I wanted to check if anyone knew/had
> strong feelings about it.
>
> I can see a good reason for not copying over tableproperties if
> they're used to store specific table state (say backup state/etc), but
> I also see a good reason for copying over table properties, with
> things like orc, which store table metadata of sorts(like
> orc.compress, or stride size, etc) in table properties, which makes a
> good case for copying them over  if a person wants to create a table
> with similar definitions to the first.
>
> -Sushanth
>

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