[DRILL-5364] Planner inserts sort for simple constant value query

• Type: Bug
• Status: Reopened
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.10.0
• Assignee: Unassigned
• Reporter: Paul Rogers
• Created: 17/Mar/17 17:17
• Updated: 17/Mar/17 21:47

Description

Consider the following query:

SELECT CURRENT_TIMESTAMP FROM (VALUES(1))

The following is the plan generated for the query. Notice the inclusion of an unnecessary sort.

  "graph" : [ {
    "pop" : "Values",
    "@id" : 4,
    "content" : [ {
      "EXPR$0" : {
        "$numberLong" : 1
      }
    } ],
    "initialAllocation" : 1000000,
    "maxAllocation" : 10000000000,
    "cost" : 1.0
  }, {
    "pop" : "project",
    "@id" : 3,
    "exprs" : [ {
      "ref" : "`CURRENT_TIMESTAMP`",
      "expr" : "current_timestamp() "
    } ],
    "child" : 4,
    "initialAllocation" : 1000000,
    "maxAllocation" : 10000000000,
    "cost" : 1.0
  }, {
    "pop" : "external-sort",
    "@id" : 2,
    "child" : 3,
    "orderings" : [ {
      "order" : "ASC",
      "expr" : "`CURRENT_TIMESTAMP`",
      "nullDirection" : "UNSPECIFIED"
    } ],
    "reverse" : false,
    "initialAllocation" : 20000000,
    "maxAllocation" : 10000000000,
    "cost" : 1.0
  }, {
    "pop" : "selection-vector-remover",
    "@id" : 1,
    "child" : 2,
    "initialAllocation" : 1000000,
    "maxAllocation" : 10000000000,
    "cost" : 1.0
  }, {
    "pop" : "screen",
    "@id" : 0,
    "child" : 1,
    "initialAllocation" : 1000000,
    "maxAllocation" : 10000000000,
    "cost" : 1.0
  } ]