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Property

Value

Notes

LOG_BUFFER_TYPE

0

OS Kernel log buffer. This is the default setting for ALTIBASE HDB. When using this setting, ALTIBASE HDB uses memory-mapped files for disk I/O related to transaction logs. With memory mapped file IO, the file to be read is mapped to the virtual memory of the underlying OS. This mode provides improved durability in the case that the database crashes but not the OS, since changes to memory-mapped files are maintained in the OS kernel memory. In this mode, log flushing is handled by the operating system leveraging msync() function.

LOG_BUFFER_TYPE

1

Process memory log buffer. When using this setting, transaction logs are written to a memory-resident log buffer. In this mode, log flushing is handled by the database process using fsync() function. This method is slightly faster than memory-mapped method, but it compromises from durability in the case of a database crash.

Relaxed Durability (Level 2)

fgfg

fg

Property

Value

COMMIT_WRITE_WAIT_MODE

 

LOG_BUFFER_TYPE

 

fg

fg

fg

Enhanced Durability (Level 3)

fgfg

fg

Property

Value

COMMIT_WRITE_WAIT_MODE

 

LOG_BUFFER_TYPE

 

fg

fg

fg

Strict Durability (Level 5)

fgfg

fg

Property

Value

COMMIT_WRITE_WAIT_MODE

 

LOG_BUFFER_TYPE

 

fg

fg

fg