Specifies the amount of memory to use for a load into a LF index.
Option can be set at the database (PUBLIC) or user level. When set at the database level, the value becomes the default for any new user, but has no impact on existing users. When set at the user level, overrides the PUBLIC value for that user only. No system privilege is required to set option for self. System privilege is required to set at database level or at user level for any user other than self.
Requires the SET ANY PUBLIC OPTION system privilege to set this option. Can be set temporary for an individual connection or for the PUBLIC role. Takes effect immediately.
LF_BITMAP_CACHE_KB defines the amount of heap memory (in KB) per distinct value used during a load into an LF index. The default allots 4KB. If the sum of the distinct counts for all LF indexes on a particular table is relatively high (greater than 10,000), then heap memory use might increase to the point of impacting load performance due to system page faulting. If this is the case, reduce the value of LF_BITMAP_CACHE_KB.
This formula shows how to calculate the heap memory used (in bytes) by a particular LF index during a load:
Heap-memory-used = (lf_bitmap_cache_kb * 1024) * lf-distinct-count-for-column
Using the default of 4KB, an LF index with 1000 distinct values can use up to 4MB of heap memory during a load.