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Posted to issues@tajo.apache.org by jihoonson <gi...@git.apache.org> on 2015/11/28 05:05:05 UTC
[GitHub] tajo pull request: TAJO-1705: Update document for index support
GitHub user jihoonson opened a pull request:
https://github.com/apache/tajo/pull/887
TAJO-1705: Update document for index support
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/jihoonson/tajo-2 TAJO-1705
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/tajo/pull/887.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #887
----
commit c912853c1e138ad23885629836e8589b80eee419
Author: Jihoon Son <ji...@apache.org>
Date: 2015-11-28T04:04:22Z
TAJO-1705
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by hyunsik <gi...@git.apache.org>.
Github user hyunsik commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46377850
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -66,4 +67,10 @@ If you don't want to use the index scan feature anymore, you can simply disable
.. note::
- Once the index scan feature is enabled, Tajo currently always performs the index scan regardless of its efficiency. You should set this option when the expected number of retrieved tuples is sufficiently small.
+ Once index scan is enabled, Tajo currently always performs index scan regardless of its efficiency. You should set this option when the expected number of retrieved tuples is sufficiently small.
--- End diff --
I suggest:
``Once index scan is enabled, Tajo will perform 'index scan' if possible. In some cases, it may cause performance degradation. If you always want to get better performance, you should either enable or disable 'index scan' according to selectivity. Usually, the performance gain of index will increase when the selectivity is low.``
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by jihoonson <gi...@git.apache.org>.
Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46380644
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -1,18 +1,19 @@
-*************************************
+*****************
How to use index?
-*************************************
+*****************
--------------------------------------
+---------------
1. Create index
--------------------------------------
+---------------
-The first step for utilizing index is index creation. You can create index using SQL (:doc:`/sql_language/ddl`) or Tajo API (:doc:`/tajo_client_api`). For example, you can create a BST index on the lineitem table by submitting the following SQL to Tajo.
+The first step for utilizing index is to create an index. You can create an index using SQL (:doc:`/sql_language/ddl`) or Tajo API (:doc:`/tajo_client_api`).
+For example, the following SQL statement can be used to create a BST index on the lineitem table.
--- End diff --
Done.
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/tajo/pull/887
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by hyunsik <gi...@git.apache.org>.
Github user hyunsik commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46376604
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -1,18 +1,19 @@
-*************************************
+*****************
How to use index?
-*************************************
+*****************
--------------------------------------
+---------------
1. Create index
--------------------------------------
+---------------
-The first step for utilizing index is index creation. You can create index using SQL (:doc:`/sql_language/ddl`) or Tajo API (:doc:`/tajo_client_api`). For example, you can create a BST index on the lineitem table by submitting the following SQL to Tajo.
+The first step for utilizing index is to create an index. You can create an index using SQL (:doc:`/sql_language/ddl`) or Tajo API (:doc:`/tajo_client_api`).
+For example, the following SQL statement can be used to create a BST index on the lineitem table.
--- End diff --
How about "statement will create"?
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by jihoonson <gi...@git.apache.org>.
Github user jihoonson commented on the pull request:
https://github.com/apache/tajo/pull/887#issuecomment-162732429
@hyunsik thanks for your comment. I've updated my patch.
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by hyunsik <gi...@git.apache.org>.
Github user hyunsik commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46377029
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -48,17 +49,17 @@ If the index is created successfully, you can see the information about that ind
For more information about index creation, please refer to the above links.
--------------------------------------
+-----------------------------
2. Enable/disable index scans
--------------------------------------
+-----------------------------
-When an index is successfully created, you must enable the index scan feature as follows:
+When an index is successfully created, you must enable index scan as follows:
--- End diff --
I suggest:
``Even though an index is successfully created, you need a further step, enabling 'index scan' as following. It is necessary because 'index scan' is disabled by default.``
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by jihoonson <gi...@git.apache.org>.
Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46380613
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -48,17 +49,17 @@ If the index is created successfully, you can see the information about that ind
For more information about index creation, please refer to the above links.
--------------------------------------
+-----------------------------
2. Enable/disable index scans
--------------------------------------
+-----------------------------
-When an index is successfully created, you must enable the index scan feature as follows:
+When an index is successfully created, you must enable index scan as follows:
--- End diff --
This section is related to the previous section ```Create index```. So, starting with ```even though``` looks not good I think.
How about ```Reading data using index is disabled by default.
So, exploiting the created index, you need a further step, enabling 'index scan' as following:```?
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by jihoonson <gi...@git.apache.org>.
Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/887#discussion_r46380653
--- Diff: tajo-docs/src/main/sphinx/index/how_to_use.rst ---
@@ -66,4 +67,10 @@ If you don't want to use the index scan feature anymore, you can simply disable
.. note::
- Once the index scan feature is enabled, Tajo currently always performs the index scan regardless of its efficiency. You should set this option when the expected number of retrieved tuples is sufficiently small.
+ Once index scan is enabled, Tajo currently always performs index scan regardless of its efficiency. You should set this option when the expected number of retrieved tuples is sufficiently small.
--- End diff --
Thanks for the good comment.
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[GitHub] tajo pull request: TAJO-1705: Update document for index support
Posted by hyunsik <gi...@git.apache.org>.
Github user hyunsik commented on the pull request:
https://github.com/apache/tajo/pull/887#issuecomment-169249834
+1 LGTM
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