[DRILL-3553] add support for LEAD and LAG window functions

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Component/s: Execution - Relational Operators
• Labels: window_function
• Assignee: Abdel Hakim Deneche
• Reporter: Abdel Hakim Deneche
• Created: 24/Jul/15 22:05
• Updated: 15/Sep/15 19:20
• Resolved: 18/Aug/15 17:18

Description

From SQL standard here is the general format of LEAD and LAG:

<window function> ::=
  <lead or lag function> OVER <window name or specification>

<lead or lag function> ::=
  <lead or lag> ( <lead or lag extent>
  [ , <offset> [ , <default expression> ] ] )
  [ <null treatment> ]

<lead or lag> ::=
  LEAD | LAG

<lead or lag extent> ::=
  <value expression>

<offset> ::=
  <exact numeric literal>

<default expression> ::=
  <value expression>

The following won't be supported until CALCITE-337 is resolved:

<null treatment> ::=
  RESPECT NULLS | IGNORE NULLS

As part of this JIRA task only the following syntax will be supported:

<lead or lag function> ::=
  <lead or lag> ( <lead or lag extent> )

Issue Links

• relates to: DRILL-3609 Support non default arguments for LEAD and LAG window functions
• requires: CALCITE-337 Support IGNORE NULLS in window aggregates