Parameter:
FTG_MAX_MB_PER_THREADShort description: Maximum permitted memory (in MB) per FT search thread — hard limit against individual memory-hungry full-text searches.
Profile
Parameter | FTG_MAX_MB_PER_THREAD |
Category | Performance / Memory |
Component | Server |
Available since | 9.0.1 (older) |
Supported versions | 9.0.1, 10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1 |
GUI equivalent | notes.ini only (no GUI) |
Possible values | Integer in MB — default 100 |
Description
FTG_MAX_MB_PER_THREAD defines the maximum amount of memory in megabytes granted to an individual FT search thread of the GTR engine (General Text Retrieval). The default value is 100 MB. If the limit is exceeded, the FT search aborts cleanly instead of continuing to request memory and thereby endangering server stability.The parameter is part of the tuning family from HCL KB0038904 and only takes full effect together with
FTG_CHECK_THREAD_MAX_MEM=1 (memory monitoring) as well as the global pool switches FTG_MAX_MEM_POOL and FTG_MB_PER_THREAD. In diagnostics it is often temporarily set to a low value (e.g. FTG_MAX_MB_PER_THREAD=10) to identify memory-hungry queries via log messages.Example configuration
Explicitly set the default value:
FTG_MAX_MB_PER_THREAD=100
Diagnostic variant (low limit, to surface memory-hungry searches):
FTG_CHECK_THREAD_MAX_MEM=1 FTG_MAX_MB_PER_THREAD=10
More generous limit for servers with sufficient RAM and large indexes:
FTG_MAX_MB_PER_THREAD=200
Notes & pitfalls
- Only effective on servers (FT engine).
- Full benefit only in combination with
FTG_CHECK_THREAD_MAX_MEM=1, otherwise it is a purely passive threshold.
- Values that are too low can cause legitimate, large full-text searches to be aborted — set values only after observation via
show stat FT.*.
- Companion parameters:
FTG_CHECK_THREAD_MAX_MEM,FTG_MAX_MEM_POOL,FTG_MB_PER_THREAD,FTG_USE_SYS_MEMORY.
- Takes effect after a server restart (classic notes.ini parameter).