Start/notes.ini Parameters/Compact_Max_Threads

Compact_Max_Threads

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Parameter: Compact_Max_Threads
Short description: Number of parallel threads of the Compact task – noticeably accelerates nightly maintenance runs on multi-core systems.

Profile

Parameter
Compact_Max_Threads
Category
Performance / Memory
Component
Server
Available since
12.0
Supported versions
12.0, 14.0, 14.5, 14.5.1
GUI equivalent
notes.ini only (no GUI)
Possible values
Integer (default 1; typically 2–8 – never > number of available cores)

Description

The classic Compact task is single-threaded and, with several thousand NSFs, can occupy entire nights. With Compact_Max_Threads=N, up to N databases are compacted in parallel. On modern servers with plenty of CPU cores, the runtime often halves or drops to a third.
Not to be confused with DBMT_* (Database Maintenance Tool) – the two mechanisms complement each other.

Example configuration

Compact_Max_Threads=4

Notes & pitfalls

  • Never set higher than the available physical cores – otherwise context-switch overhead.
  • On I/O-bound storage (HDD/SAN), parallel compaction brings little benefit.
  • Complements Debug_Compact, DBMT_*, and Update_* parameters.
  • On memory-constrained systems, scale up cautiously – each Compact instance allocates its own memory.
  • The change takes effect with the next Compact invocation; a restart is not strictly required.