[carbondata] 18/22: [DOC] Update doc for sort_columns modification

[ra...@apache.org]

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ravipesala pushed a commit to branch branch-1.5
in repository https://gitbox.apache.org/repos/asf/carbondata.git

commit 4d21b6a8cb7fb3f5b70fd862bbbba78e5f0f12bd
Author: QiangCai <qi...@qq.com>
AuthorDate: Mon May 6 10:39:19 2019 +0800

    [DOC] Update doc for sort_columns modification
    
    Update doc for sort_columns modification
    
    This closes #3203
---
 docs/ddl-of-carbondata.md | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/docs/ddl-of-carbondata.md b/docs/ddl-of-carbondata.md
index 88615a2..5bc8f10 100644
--- a/docs/ddl-of-carbondata.md
+++ b/docs/ddl-of-carbondata.md
@@ -793,6 +793,27 @@ Users can specify which columns to include and exclude for local dictionary gene
        ALTER TABLE tablename UNSET TBLPROPERTIES('SORT_SCOPE')
        ```
 
+     - ##### SORT COLUMNS
+       Example to SET SORT COLUMNS:
+       ```
+       ALTER TABLE tablename SET TBLPROPERTIES('SORT_COLUMNS'='column1')
+       ```
+       After this operation, the new loading will use the new SORT_COLUMNS. The user can adjust 
+       the SORT_COLUMNS according to the query, but it will not impact the old data directly. So 
+       it will not impact the query performance of the old data segments which are not sorted by 
+       new SORT_COLUMNS.  
+       
+       UNSET is not supported, but it can set SORT_COLUMNS to empty string instead of using UNSET.
+       ```
+       ALTER TABLE tablename SET TBLPROPERTIES('SORT_COLUMNS'='')
+       ```
+
+       **NOTE:**
+        * The future version will enhance "custom" compaction to sort the old segment one by one.
+        * The streaming table is not supported for SORT_COLUMNS modification.
+        * If the inverted index columns are removed from the new SORT_COLUMNS, they will not 
+        create the inverted index. But the old configuration of INVERTED_INDEX will be kept.
+
 ### DROP TABLE
 
   This command is used to delete an existing table.