Please forget my first mail. After that, I inspected this issue more
precisely and concluded that we don't have to fill up HiveCatalogStore's
tablespace methods[^1] - it is better to remove them.
Here is why.

Those methods were added to CatalogStore interface and its implementation
classes, AbstractDBStore and HiveCatalogStore in commit 3ba2624[^2]
and commit 8982684[^3]. But actually, those methods in AbstractDBStore are
not related to tablespace feature. Its CatalogConstants#TB_SPACES table,
which is used in accompany with CatalogConstants#TB_DATABASES table, stores
only default tablespace name and warehouse directory. If you are in doubt,
please check where CatalogStore#createTablespace is invoked - it is only
invoked in TajoMaster#checkBaseTBSpaceAndDatabase via CatalogService RPC.
Because tablespaces are defined using json configuration file, those
methods seem useless.

In my opinion, it is better to remove them from CatalogStore and their
implementation classes. In that case, the fact they are not implemented in
HiveCatalogStore[^4] never be a problem.

I am looking forward to your answer. Thanks.


p.s. I checked for HiveCatalogStore's statistics feature and concluded that
it should be not so hard to resolve TAJO-2173[^5], even it is not perfect.

[^1]: createTablespace, existTablespace, dropTablespace,
getAllTablespaceNames, getTablespaces, getTablespace, alterTablespace.
[^2]: TAJO-353: Add Database support.

On Mon, Sep 12, 2016 at 6:15 PM, Hyunsik Choi <[EMAIL PROTECTED]> wrote:
*Dongjin Lee*
*Software developer in Line+.So interested in massive-scale machine
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