arangosh> db._explain('FOR x IN 1..10 LET then=DATE_NOW() FOR y IN 1..10 LET now=DATE_NOW() LET nowstr=CONCAT(now, x, y, then) RETURN nowstr', {}, {colors: false})
Query string:
 FOR x IN 1..10 LET then=DATE_NOW() FOR y IN 1..10 LET now=DATE_NOW() LET nowstr=CONCAT(now, x, y, 
 then) RETURN nowstr

Execution plan:
 Id   NodeType            Est.   Comment
  1   SingletonNode          1   * ROOT
  2   CalculationNode        1     - LET #5 = 1 .. 10   /* range */   /* simple expression */
  3   EnumerateListNode     10     - FOR x IN #5   /* list iteration */
  4   CalculationNode       10       - LET then = DATE_NOW()   /* v8 expression */
  6   EnumerateListNode    100       - FOR y IN #5   /* list iteration */
  7   CalculationNode      100         - LET now = DATE_NOW()   /* v8 expression */
  8   CalculationNode      100         - LET nowstr = CONCAT(now, x, y, then)   /* simple expression */
  9   ReturnNode           100         - RETURN nowstr

Indexes used:
 none

Optimization rules applied:
 Id   RuleName
  1   move-calculations-up
  2   remove-redundant-calculations
  3   remove-unnecessary-calculations


arangosh> db._explain('LET now=DATE_NOW() FOR x IN 1..10 FOR y IN 1..10 LET nowstr=CONCAT(now, x, y, now) RETURN nowstr', {}, {colors: false})
Query string:
 LET now=DATE_NOW() FOR x IN 1..10 FOR y IN 1..10 LET nowstr=CONCAT(now, x, y, now) RETURN nowstr

Execution plan:
 Id   NodeType            Est.   Comment
  1   SingletonNode          1   * ROOT
  3   CalculationNode        1     - LET #4 = 1 .. 10   /* range */   /* simple expression */
  2   CalculationNode        1     - LET now = DATE_NOW()   /* v8 expression */
  4   EnumerateListNode     10     - FOR x IN #4   /* list iteration */
  6   EnumerateListNode    100       - FOR y IN #4   /* list iteration */
  7   CalculationNode      100         - LET nowstr = CONCAT(now, x, y, now)   /* simple expression */
  8   ReturnNode           100         - RETURN nowstr

Indexes used:
 none

Optimization rules applied:
 Id   RuleName
  1   move-calculations-up
  2   remove-redundant-calculations
  3   remove-unnecessary-calculations