208 lines
11 KiB
Markdown
208 lines
11 KiB
Markdown
# 🏛️ Oracle Database
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## Přehled
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Oracle Database je proprietární relační databáze s nejširší škálou enterprise funkcí — RAC clustering, Active Data Guard, partitioning, advanced compression, in-memory options a Oracle Exadata integrace. Dominantní v korporátním světě, financích, telekomunikacích a mainframe ekosystému.
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## Architektura
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### Oracle instance + database
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```
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Oracle Instance (memory + processes)
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├── System Global Area (SGA)
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│ ├── Database Buffer Cache
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│ ├── Shared Pool (library cache, dictionary cache)
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│ ├── Redo Log Buffer
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│ ├── Java Pool
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│ ├── Large Pool (backup, parallel)
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│ └── In-Memory Column Store (option)
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├── Program Global Area (PGA) — per session
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└── Background processes
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├── PMON (process monitor)
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├── SMON (system monitor)
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├── DBWn (database writer)
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├── LGWR (log writer)
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├── CKPT (checkpoint)
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├── ARCn (archiver)
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└── MMON (manageability monitor)
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```
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### Multitenant architektura (12c+)
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```
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Container Database (CDB)
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├── Root (CDB$ROOT) — metadata, system objects
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├── Seed (PDB$SEED) — template pro nové PDB
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├── Pluggable Database 1 (PDB1) — aplikace A
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├── Pluggable Database 2 (PDB2) — aplikace B
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└── Pluggable Database 3 (PDB3) — aplikace C
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```
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Každé PDB vypadá jako samostatná databáze, ale sdílí SGA a background procesy. Výhoda: vyšší densita, jednodušší patchování (CDB úroveň), resource management per PDB.
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### Oracle RAC (Real Application Clusters)
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Multi-instance architektura — více serverů přistupuje ke stejné storage:
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```text
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Node 1 ─── Oracle ASM ─── Shared Storage (SAN/NFS)
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Node 2 ─── Oracle ASM ─── Shared Storage (SAN/NFS)
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Node 3 ─── Oracle ASM ─── Shared Storage (SAN/NFS)
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│
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Cache Fusion (private interconnect)
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```
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- Až 64 nodů v clusteru
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- **Cache Fusion** — transfer dirty blocks mezi instancemi přes private interconnect (RAC-specific)
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- **ASM** (Automatic Storage Management) — clustered filesystem + volume manager
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- **Service** — workload routing (primární, report, batch)
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### Oracle Data Guard
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| Režim | Ochrana | Latence | Use case |
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|-------|---------|---------|----------|
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| **Maximum Protection** | Zero data loss (sync) | Nejvyšší | Kritické systémy |
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| **Maximum Availability** | Zero data loss (sync, fallback na async) | Vysoká | Enterprise standard |
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| **Maximum Performance** | Async | Nejnižší | DR na dálku |
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- **Active Data Guard** — standby pro čtení (reporting, backup) — vyžaduje licenci
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- **Far Sync** — synchronní zápis na vzdálený standby přes async (kompromis)
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### Oracle Exadata
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Hardware+software platforma pro Oracle DB:
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| Komponenta | Popis |
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|-----------|-------|
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| **Database Servers** | x86 (Xeon), 2-8× per rack, NVMe, 1.5-6 TB RAM |
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| **Storage Servers** | Celková kapacita až 2.7 PB raw per rack |
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| **Smart Scan** | Predikátová filtrace na storage vrstvě (místo v DB serveru) |
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| **Smart Flash Cache** | Násobné vrstvy caching (RAM, Flash, disk) |
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| **RDMA over Converged Ethernet** | Nízká latence mezi DB a storage servery |
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Vhodné pro: největší OLTP, data warehousing, consolidation.
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## Klíčové enterprise funkce
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| Funkce | Popis | Konkurence |
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|--------|-------|------------|
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| **RAC** | Shared-everything cluster až 64 uzlů | MSSQL AlwaysOn FCI (2 uzly) |
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| **Active Data Guard** | Standby pro čtení, far sync, automatic failover | MSSQL AlwaysOn AG, PostgreSQL streaming |
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| **Partitioning** | Range, List, Hash, Composite, interval, reference | PostgreSQL (declarative partitioning 10+) |
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| **Advanced Compression** | Columnar, HCC (Exadata), OLTP compression | InnoDB page compression, PG TOAST |
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| **In-Memory** | Column store v SGA pro real-time analytics | PG (no native), MSSQL (columnstore index) |
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| **Advanced Security** | TDE, data redaction, VPD, audit vault, database firewall | PG (pgcrypto, pgaudit), MSSQL (TDE, Always Encrypted) |
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| **Flashback** | Dotazování na historická data (Flashback Query, Table, Database) | PG (temporal tables via extension), MSSQL (system-versioned) |
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| **Sharding** | System-managed, composite, user-defined | MongoDB (native), Vitess (MySQL), Citus (PG) |
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| **ASM** | Clustered filesystem + volume manager | VMware VMFS, Windows CSV |
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## Oracle licensing detail
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### Edice
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| Edice | Metrika | Cena (orientační) | Limitace |
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|-------|---------|-------------------|----------|
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| **Oracle Database Standard Edition 2 (SE2)** | Per core (core factor 0.5) | ~$17 500/core | Max 16 CPU threads (na server), max 2 sockets, žádný RAC (pouze Oracle RAC One), žádné partitioning, in-memory, compression |
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| **Oracle Database Enterprise Edition (EE)** | Per core (core factor 0.5) | ~$47 500/core | Bez omezení, všechny funkce (RAC, partitioning, in-memory, compression, Advanced Security) — ale vše jako **volitelné licence** |
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| **Oracle Database Enterprise Edition (RAC)** | Per core (EE + RAC option) | ~$47 500 + $23 000/core | EE + RAC clustering |
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### Volitelné licence (options) — EE only
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| Option | Cena (orientační / core) | Use case |
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|--------|--------------------------|----------|
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| **Real Application Clusters (RAC)** | ~$23 000 | Multi-instance cluster |
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| **Active Data Guard** | ~$10 000 | Standby pro čtení, far sync, automatic failover |
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| **Partitioning** | ~$11 500 | Range, list, hash, interval, reference, system |
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| **Advanced Compression** | ~$11 500 | OLTP compression, HCC (Exadata), JSON compression |
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| **Advanced Security** | ~$15 000 | TDE, data redaction, database firewall |
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| **In-Memory Database** | ~$23 000 | Column store v SGA pro real-time analytics |
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| **Database Vault** | ~$5 750 | Separation of duties, multi-tenancy security |
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| **Multitenant (EE)** | Zdarma (od 21c) | CDB/PDB — max 3 PDB na CDB v EE bez license. Neomezeno s Multitenant option (~$17 500) |
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| **Spatial / Graph** | ~$5 750 | Geoprostorová data, property graph |
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| **Label Security** | ~$5 750 | Row-level security s klasifikacemi |
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### Oracle Cloud (OCI) licensing
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| Služba | Model | Cena | Poznámka |
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|--------|-------|------|----------|
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| **OCI Base Database (RDS-like)** | BYOL nebo License Included | ~$1-5/hod (BYOL levnější) | Single instance nebo RAC, automatické backup, patching |
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| **OCI Exadata Database Service** | BYOL nebo License Included | ~$5-30/hod (dle shape) | Exadata X9M/X10M v OCI, elastic, full Exadata features |
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| **OCI Autonomous Database** | Per CPU (ECPU) | ~$0.50-3.00/ECPU/hod | Auto-tuning, auto-scaling, auto-patching |
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| **BYOL (Bring Your Own License)** | Vlastní Oracle license v OCI | Jen infrastruktura | Lze použít stávající perpetual license, včetně supportu |
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### RAC sizing — licence cost
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```text
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4-node RAC, každý node 2× EPYC 9654 (96C) = 192 cores per node
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Core factor 0.5 → 96 Oracle licenses per node
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4 × 96 = 384 Oracle EE licenses
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EE: 384 × $47 500 = $18 240 000
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RAC option: 384 × $23 000 = $8 832 000
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Support 22 % ročně: ($18 240 000 + $8 832 000) × 0.22 = $5 955 840/rok
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Tip: Pro RAC zvažte menší CPU (např. 64C místo 96C) — license cost často převyšuje hardware cost.
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```
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### Oracle vs PostgreSQL — srovnání
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| Oblast | Oracle | PostgreSQL |
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| **Licence** | Proprietary (per core, ~$17.5k-47.5k/core + 22 % support ročně) | Open source (PostgreSQL license, MIT-like) |
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| **RAC clustering** | Nativní, shared-everything | Žádné (Citus = shared-nothing) |
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| **Multitenant** | CDB/PDB architektura | Žádné (schemas per tenant) |
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| **Parallel execution** | Vyspělý (auto DOP, parallel index scan) | Dobrý (parallel seq/index scan, join) |
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| **Storage management** | ASM (integrovaný) | OS volume / LVM |
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| **Materialized views** | S refresh on commit, query rewrite | Není query rewrite |
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| **Partitioning** | 40+ možností (interval, referential, system) | Declarative (range, list, hash od 10+) |
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| **In-memory** | Columnar in SGA | Není nativní |
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| **Standby použitek** | Active Data Guard (read-only, licence) | Hot standby (read-only, zdarma) |
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| **Cloud** | OCI (Oracle Cloud), AWS RDS, Azure | Všechny cloudy (native) |
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## Doporučení — v čem je Oracle lepší
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| Oblast | Oracle | Konkurence | Proč Oracle |
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|--------|--------|------------|-------------|
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| **Licence cost (4-node RAC, 384 cores)** | ~$50M (1. rok vč. supportu) | PostgreSQL: $0 | Oracle: 22 % support ročně z license fee |
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| **Vendor lock-in** | Vysoký (GoldenGate migrace náročná, PL/SQL specific) | PostgreSQL: žádný | MySQL i PG mají nástroje pro migraci z Oracle (ora2pg, AWS DMS) |
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| **Enterprise OLTP** | RAC + ASM, zero-downtime patching | MSSQL (FCI limit 2 nodes) | Shared-everything cluster, transparent failover |
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| **Finance / Banking** | Audit Vault, Database Vault, TDE, VPD | PG (pgaudit, row-level security) | Compliance certifikace (SOX, PCI, GDPR) |
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| **Consolidace** | Multitenant (CDB/PDB) — stovky DB na 1 instanci | PG (citizen schemas) | Nižší overhead, jednodušší management |
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| **Data Warehouse** | Exadata Smart Scan, parallel execution, in-memory | ClickHouse (specializovaná) | Hybrid workload (OLTP + DW v jedné DB) |
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| **High-end hardware** | Exadata engineered system | PG (běží na čemkoliv) | Full-stack optimalizace HW+SW |
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| **Partitioning** | Rozsah možností (reference, interval, system) | PG (basic) | 10+ let náskok v implementaci |
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| **Flashback / recovery** | Flashback Database, Table, Query — libovolný čas | PG (PITR, point-in-time) | Rychlejší, granularnější recovery |
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| **Ekosystém** | OEM, Data Pump, SQL Developer, Toad, GoldenGate | PG (pgAdmin, pg_dump, Patroni) | Desítky let enterprise toolingu |
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### Kdy použít Oracle
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- **Kritické OLTP systémy** — banking, payment processing, trading
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- **Enterprise konsolidace** — stovky DB na jednom RAC clusteru (multitenant)
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- **Regulované prostředí** — finance, healthcare, government (audit, security, compliance)
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- **Oracle ekosystém** — E-Business Suite, PeopleSoft, Siebel, JD Edwards
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- **Exadata zákazníci** — maximální výkon pro hybrid workload (OLTP + DW)
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- **GoldenGate replikace** — heterogenní replikace (Oracle → Kafka, Oracle → PostgreSQL)
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- **Cloud migration** — OCI, AWS RDS for Oracle, Azure Oracle Database Service
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### Kdy použít něco jiného
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- **Startup / SME** → PostgreSQL (zdarma, dostatečný výkon, žádný vendor lock-in)
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- **Web / LAMP stack** → MySQL (jednodušší, levnější, široká podpora)
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- **Cloud-native** → Aurora, CockroachDB (architektura pro cloud, ne port on-prem do cloudu)
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- **Potřebujete jen SQL** → PostgreSQL (Oracle overhead se nevyplatí)
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- **Horizontální škálování zápisů** → Cassandra (RAC škáluje čtení, zápisy jdou přes jeden nod)
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## Zdroje
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Odkazy, knihy a standardy: [sources/databases/sources.md](sources/databases/sources.md)
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### Doporučená literatura
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| Kniha | Autoři | ISBN | Popis |
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|-------|--------|------|-------|
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| Oracle Database 23ai New Features | Oracle Corporation | — | Oficiální průvodce novinkami — AI Vector Search, JSON Relational Duality, property graphs, schema privileges |
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| Expert Oracle Architecture (3rd ed.) | Thomas Kyte, Darl Kuhn | 978-1484249602 | Komplexní výklad Oracle architektury — od storage po RAC a Data Guard |
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*Poslední revize: 2026-06-03*
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