WL#3870: New Falcon@@ settings
Affects: Server-6.0 — Status: Complete — Priority: Medium
Three new settings are being added to the server @@ variables, now that worklog 1722 is done and they can be done without changing the server code. These settings already exist in the Falcon engine and are now being exposed. They can be set at any time, but are only applied to Falcon the first time a Falcon table is accessed. Name: falcon_log_windows Description: The number of memory windows allocated for Falcon serial log. Minimum: 10 Maximum: 32768 Default: 10 Background: Each of these windows are 1 Mbyte in size, so you don't want to have more than you really need. When these are all used by concurrent threads, however, things will start to back up. At present, this number of serial log windows is allocated for each serial log. But in the future, this will be a maximum number of windows, and Falcon will allocate only what it needs for concurrent threads, but not more than this number. Name: falcon_index_chill_threshold Description: Mbytes of pending index data that is 'frozen' to the Falcon serial log.. Minimum: 1 Maximum: 1024 Default: 4 Background: This is the number of Mbytes of pending index data that Falcon will store during a large transaction before flushing these index changes to the serial log. This 'flushing' is called 'chilling' the index since it makes the data not immediately available. If the index is unique, or the transaction regularly re-reads this index data, it stays in memory. Chilling pending indexes helps Falcon to accomplish very large data loads in a single transaction without running out of memory. See Worklog 3714. Name: falcon_record_chill_threshold Description: Mbytes of pending record data that is 'frozen' to the Falcon serial log. Minimum: 1 Maximum: 1024 Default: 5 Background: This is the number of Mbytes of pending record data that Falcon will keep in memory during a large transaction before flushing these records to the serial log. This 'flushing' is called 'chilling' since it makes the data not immediately available. If chilled records are accessed again during the transaction, they are immediately restored (thawed) from the serial log. Chilling pending records helps Falcon to accomplish very large transactions without running out of memory. See Worklog 3722.
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