Use Buffer Hash Latch Factor (-hashLatchFactor) to tailor the number of latches allocated for the Buffer pool Hash Table (BHT) entries. The number of latches allocated is calculated based on the percent you specify.

Operating system and syntax UNIX / Windows -hashLatchFactor n
Use with Maximum value Minimum value Default
Database Server 100 5 10
n

The number of BHT latches to create, specified as a percent of the BHT size, and rounded down to a whole number.

The size of the BHT defaults to approximately 25 percent of the value of -B. Therefore, if -B is set at 50000, then the buffer hash table defaults to approximately 13000 entries. If you leave -hashLatchFactor at the default of 10 percent, 1300 latches are allocated at startup.

Notes

  • The number of latches allocated by the value of Buffer Hash Latch Factor (-hashLatchFactor) is fixed at startup of the primary database broker, and can not be modified while the database is online.
  • If Buffer Hash Latch Factor (-hashLatchFactor) is specified on a connection other than the primary database broker, the value is validated as accurate and then ignored. If the validation fails, the connection is refused.
  • The minimum number of latches that may be allocated is 2.
  • You can set the size of the BHT with the -hash startup parameter.