Access plans - examples

Examples of access plans illustrate the difference between plan execution with and without asynchrony optimization.

The first two examples show how the union and merge join plans in Asynchronous processing of federated queries - examples look when asynchrony is enabled.

For simplicity, the examples show plans with SHIP operators only. Asynchrony optimization transforms the plan the same way for RPD operators as for SHIP operators. SHIP and RPD operators are interchangeable, unless otherwise noted.

Example 1a: Plan without asynchrony

  
        RETURN	
           |	
         UNION	
       /   |   \	
    SHIP SHIP SHIP

Example 1b: Plan with asynchrony

  
        RETURN	
           |	
         UNION	
       /   |   \	
    SHIP  ATQ  ATQ
           |    |
         SHIP  SHIP

Example 2a: Plan without asynchrony

  
         RETURN	
            |
         MSJOIN
         /    \
       SCAN   FILTER
         |       |
       SORT    SCAN
         |       |
       SHIP    SORT
                 |
               SHIP

Example 2b: Plan with asynchrony

  
         RETURN	
            |
         MSJOIN
         /    \
       SCAN   FILTER
         |       |
       SORT    SCAN
         |       |
       SHIP    SORT
                 |
                ATQ
                 |
               SHIP

Example 3a: Plan without asynchrony

  
         RETURN	
            |
          HSJN
         /    \	
       SHIP   SHIP

Example 3b: Plan with asynchrony

  
         RETURN	
            |
          HSJN
         /    \	
       ATQ   SHIP
        |
      SHIP

Example 4a: Plan without asynchrony

  
         RETURN	
            |
          NLJN
         /    \
       SHIP   SCAN
               |
              TEMP
               |
              SHIP

Example 4b: Plan with asynchrony

  
         RETURN	
            |
          NLJN
         /    \
       SHIP   SCAN
               |
              TEMP
               |
              ATQ
               |
              SHIP

Example 5a: Plan without asynchrony

  
         RETURN	
            |
          UNION
         /    \
       SHIP   SHIP
               |
              NLJN
             /    \
          SHIP    NICK2
            |
          SHIP
            |
          NICK1
RPDs cannot replace the SHIP-SHIP pair in this plan.

Example 5b: Plan with asynchrony

  
         RETURN	
            |
          UNION
         /    \
       SHIP   SHIP
               |
              NLJN
             /    \
          SHIP    NICK2
            |
           ATQ
            |
          SHIP
            |
          NICK1

Example 6a: Plan without asynchrony

  
         RETURN	
            |
         MSJOIN
         /    \
       SHIP   FILTER
                |
               SCAN
                 |
               SORT
                 |
               HSJN
               /   \
             SHIP  SHIP

Example 6b: Plan with asynchrony

  
         RETURN	
            |
         MSJOIN
         /    \
       SHIP   FILTER
                |
               SCAN
                 |
               SORT
                 |
               HSJN
               /   \
             ATQ   ATQ
              |     |
            SHIP   SHIP

Example 7a: Plan without asynchrony

  
                              RETURN	
                                 |
                               UNION
         - - - - - - - - - - - - - - - - - - - - - 
        |                        |                 |	
      MSJOIN                   SHIP               TQ	
         - - - - - - -                             |
        |              |                          LOCAL
     MSJOIN          FILTER
    /      \           |
SHIP       FILTER     SHIP
              |
            SCAN	
              |
            SORT
              |
            SHIP

Example 7b: Plan with asynchrony

  
                              RETURN	
                                 |
                               UNION
         - - - - - - - - - - - - - - - - - - - - - 
        |                        |                 |	
      MSJOIN                    ATQ               TQ	
         - - - - - - -           |                 |
        |              |        SHIP             LOCAL
     MSJOIN          FILTER
    /      \           |
SHIP       FILTER     ATQ
              |        |
            SCAN      SHIP
              |
            SORT
              |
             ATQ
              |
            SHIP