RV_MERGE_TABLE_MEMPERCENT Option

An automated merge of the row-level versioned (RLV) store and IQ main stores occurs based on the merge thresholds, including RV_MERGE_TABLE_MEMPERCENT. If this table threshold is exceeded, a merge will be triggered for the specific table.

Allowed Values

0 - 100 (percent)

Default

0 (percent)

Note: When RV_MERGE_TABLE_MEMPERCENT = 0, then the system uses a (per-table) threshold of 100% / N, where N is the number of RLV-enabled tables that have been loaded.

Scope

Option can be set at the database (PUBLIC) level only.

Requires the SET ANY SYSTEM OPTION system privilege to set this option. Takes effect immediately.

Remarks

This option sets the percentage of memory used as a merge threshold for an RLV-enabled table. If the memory used surpasses the threshold, a merge will occur.

The system evaluates whether to merge the RLV and IQ main stores on a per-table basis.  It enumerates through all loaded RLV tables, and for each one decides whether a merge is warranted.   A merge for a single table is deemed warranted if:
  1. The table violates either the memory threshold (RV_MERGE_TABLE_MEMPERCENT) or the row threshold (RV_MERGE_TABLE_NUMROWS), and
  2. The system does not determine that a large percentage of the RLV rows are uncommitted, and are therefore unable to be merged.