CLEAR_FETCH_QUEUE

Eon Mode only

Removes all entries or entries for a specific transaction from the queue of fetch requests of data from the communal storage. You can view the fetch queue by querying the DEPOT_FETCH_QUEUE system table. This function removes all of the queued requests synchronously. It returns after all the fetches have been removed from the queue.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

CLEAR_FETCH_QUEUE([transaction_id])

Parameters

*transaction_id*

The id of the transaction whose fetches will be cleared from the queue. If this value is not specified, all fetches are removed from the fetch queue.

Examples

This example clears all of the queued fetches for all transactions.

=> SELECT CLEAR_FETCH_QUEUE();

    CLEAR_FETCH_QUEUE

--------------------------

Cleared the fetch queue.

(1 row)

This example clears the fetch queue for a specific transaction.

=> SELECT node_name,transaction_id FROM depot_fetch_queue;
      node_name       |  transaction_id
----------------------+-------------------
 v_verticadb_node0001 | 45035996273719510
 v_verticadb_node0003 | 45035996273719510
 v_verticadb_node0002 | 45035996273719510
 v_verticadb_node0001 | 45035996273719777
 v_verticadb_node0003 | 45035996273719777
 v_verticadb_node0002 | 45035996273719777

(6 rows)

=> SELECT clear_fetch_queue(45035996273719510);
    clear_fetch_queue
--------------------------
 Cleared the fetch queue.
(1 row)

=> SELECT node_name,transaction_id from depot_fetch_queue;
      node_name       |  transaction_id
----------------------+-------------------
 v_verticadb_node0001 | 45035996273719777
 v_verticadb_node0003 | 45035996273719777
 v_verticadb_node0002 | 45035996273719777

(3 rows)