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https://issues.apache.org/jira/browse/TRAFODION-2520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15898690#comment-15898690
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ASF GitHub Bot commented on TRAFODION-2520:
-------------------------------------------
Github user liuyu000 commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/990#discussion_r104583550
--- Diff: docs/sql_reference/src/asciidoc/_chapters/olap_functions.adoc ---
@@ -26,8 +26,20 @@
[[olap_functions]]
= OLAP Functions
-This section describes the syntax and semantics of the On Line
-Analytical Process (OLAP) window functions. The OLAP window functions
+On-line Analytical Process (OLAP) functions provide the capability to
partition source data into groups of rows, order the rows in each group,
compute aggregates within a window frame for a row. Typically, an OLAP function
in SQL is expressed in two components <FUNCTION> and <OVER>: <FUNCTION>
specifies the function and the arguments, and <OVER> specifies the
partitioning, the ordering and the window frames. <OVER> is sometimes called
the window. OLAP functions are used to perform analytic tasks against data sets
stored in or computed from a set of tables, such as moving average and ranks.
+
+Trafodion also supports a set of sequence functions which are SQL
extensions and have to be used together with a SEQUENCE BY clause. These
sequence functions can be used to compute a running quantity of a column up to
and include the current row as follows.
--- End diff --
Thanks Hans & Ming.
I've updated this part based on your advice to improve the readability. :)
> Add details for OLAP function + Add LEAD, LAG, FIRST_VALUE & LAST_VALUE
> window functions
> ----------------------------------------------------------------------------------------
>
> Key: TRAFODION-2520
> URL: https://issues.apache.org/jira/browse/TRAFODION-2520
> Project: Apache Trafodion
> Issue Type: Documentation
> Reporter: Liu Yu
> Assignee: Liu Yu
>
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