Atlas index build tier defaults
Parent: Index build resource limits (maxNumActiveUserIndexBuilds, disk space) · Published reference · snapshot 2026-10-23 · skill mongodb-cohort-88cc8939dcad
↓ Facts as markdownall context files
Source-anchored research for Atlas index build tier defaults. Run status: COMPLETED.
These notes link each claim to its source. Some citations identify archived research reports that are no longer hosted on this site. A published reference means the content is available; it does not certify independent review or accuracy.Read the editorial policy and follow the sources before relying on a claim.
Structure and components
- A diagnostic gist created on 2023-08-15 contains Atlas-named hosts and maxIndexBuildMemoryUsageMegabytes=250. It demonstrates a historical configured value, but does not identify an Atlas tier or establish a current service default. (low confidence) (verified as of 2023-08-15) [source]
How it works
- The index-build memory allowance is shared across indexes created by one createIndexes command, separately from WiredTiger cache memory; exceeding the allowance causes temporary files to be used. (high confidence) [source]
- A createIndexes request consumes one concurrency slot even when it builds multiple indexes; the request shares its memory budget among those indexes. (medium confidence) [source]
Measurements and reference values
- Atlas maxIndexBuildMemoryUsageMegabytes defaults are M10–M20: 100 MB; M30: 250 MB; M40: 400 MB; M50–M60: 512 MB; M80–M140: 1024 MB; M200+: 2048 MB. The documentation labels tiers as comparable to instance-RAM bands. (high confidence) (verified as of 2026-10-23) [source]
- The generic 200 MB per-createIndexes default is explicitly scoped to self-hosted deployments; it should not replace the Atlas tier table in capacity estimates. (high confidence) (verified as of 2026-10-23) [source]
- Percona’s August 5, 2019 article describes a 500 MB default and configurable memory, so its figures should not substitute for the current Atlas tier table. (medium confidence) [source]
Problems, failure modes and limitations
- MongoDB documents Atlas index-build memory values as cluster-tier defaults that users cannot change. (high confidence) (verified as of 2026-10-23) [source]
Comparisons and alternatives
- The generic 200 MB memory and three-concurrent-build defaults describe self-managed deployments; Atlas uses tier-specific values. Memory exhaustion during sorting can spill to temporary files rather than immediately aborting the build. (medium confidence) (verified as of 2026-10-19) [source]
Facts and statements
- Atlas maxNumActiveUserIndexBuilds defaults are 1 for M10–M40, 2 for M50–M60, and 3 for M80 and above including NVMe variants; corresponding low-CPU R tiers use the same defaults. (medium confidence) (verified as of 2026-10-23) [source]
- A diagnostic gist created August 15, 2023 records maxIndexBuildMemoryUsageMegabytes=250 and maxNumActiveUserIndexBuilds=3. It is a deployment snapshot, not a current tier-default specification. (low confidence) [source]
Children
- No children recorded.