| Ops | Too many concepts (Zone / Observer / tenant / resource unit / Primary Zone); slow DBA onboarding | All versions | open (improving in the 4.x toolchain) |
| Ops | Troubleshooting often requires deep kernel knowledge; slow-SQL diagnosis depends on internal views like GV$SQL_AUDIT; inspection SQL must include a time window + tenant filter or it drags down production | All versions | partially-fixed (ODC / OCP observability improved; weak-consistency reads available for high-frequency inspections) |
| Ops | Large system-view differences between 3.x and 4.x (GV$OB_PROCESSLIST / GV$OB_LOCKS are new in 4.x); copying inspection SQL from old blogs may fail outright | 3.x→4.x | open (check version-specific docs) |
| Ops | Hard dependency on NTP clock sync; OBServer won't start under severe clock drift; extra caution needed for VM deployments | All versions | open (infrastructure prerequisite) |
| Resources | High Observer memory footprint; overkill for small deployments — worse single-node price/performance than MySQL / PostgreSQL | All versions | open (evaluate needs before selecting) |
| Resources | During write floods the memstore grows faster than dumps drain it, triggering unplanned compactions, in extreme cases error 4030 (Over tenant memory limits); leaders in the local zone are migrated before compaction | All versions | open (plan compaction windows + write-throttling runbook) |
| Performance | Read amplification after frequent updates / deletes degrades point lookups; mitigated by manual compaction or adaptive Table Mode | All versions | partially-fixed (4.x adaptive improvements) |
| Performance | Cross-partition transactions go through 2PC — poor transaction modeling carries a heavy performance tax; large transactions are bound by memtable memory limits, so ETL must be batched | All versions | open (avoid via schema design) |
| Compatibility | Early versions differ from MySQL in complex SQL, stored procedures, and function behavior; migrations require regression testing | Mostly 3.x | partially-fixed (4.x keeps closing compatibility gaps) |
| Compatibility | Oracle-mode deep waters: DBMS_LOCK.REQUEST/RELEASE unavailable, combined ALTER MODIFY changes throw -4007, async DDL exposes _hidden_ intermediate tables, UROWID/XMLTYPE/BFILE/nested tables/VARRAY unsupported | 4.x | open (POC each item) |
| Versioning | Community vs Enterprise feature differences (management, security, some HA capabilities); check the edition comparison before selecting | All versions | open |
| Versioning | Major architectural changes from 3.x to 4.x; upgrading old versions needs dedicated planning | 3.x→4.x | fixed-in-v4.x (new deployments go straight to 4.x) |
| Ecosystem | Third-party tool / ORM adaptation maturity lags the MySQL / PostgreSQL ecosystems | All versions | partially-fixed |