Tells the optimiser it can depend on a primary key or unique constraint when rewriting queries, perhaps dropping a join or a DISTINCT. The keys remain unenforced, and this works only on serverless compute or on pro or serverless SQL warehouses.
Read more: Databricks docs
In the Ultra Transcenders books
Each book explains RELY in context, with comparison tables and the common traps.
Terms in this definition
- Primary key
Uniquely identifies every row in a relational table, using one column or several together. A foreign key in another table holds this value to reference the row.
- UNIQUE constraint
A rule preventing repeated values in a column, or combination of columns, other than the primary key; a unique index enforces it. A single NULL is permitted, which a primary key does not allow.
- JOIN
Combines rows from two or more tables in one SELECT, most often by pairing a primary key with the foreign key that refers to it.
- DISTINCT
Removes duplicates so that each row appears once; it can be used in a
SELECT, an aggregate or a set operation. - KEYS
Lists the column or columns that identify each target row uniquely in an AUTO CDC statement.
- Serverless compute
Azure Machine Learning compute provided on demand whenever a job names no compute target. No cluster needs creating or managing, and jobs do not wait in a queue behind one another.
- Serverless
Compute tier for single Azure SQL databases that scales automatically, pauses when idle and charges by the second. It is offered in General Purpose and Hyperscale, not Business Critical, and reserved capacity does not apply.
Related terms
- ABFS
Short for Azure Blob File System driver. Hadoop, Spark and HDInsight rely on this HDFS-compatible connector to read and write ADLS Gen2 data.
- AMD SEV-SNP
Hardware feature from AMD that encrypts and isolates virtual machine memory; the confidential VM series DCasv5/DCadsv5 and ECasv5/ECadsv5 rely on it.
- Appliance VCF Identity Broker model
Runs VCF Identity Broker as its own three-node cluster in a management domain, added after initial deployment via VCF Operations fleet management, so logins keep working if a host fails and don't rely on vCenter. It suits platforms needing critical uptime or spanning several instances and sites, and supports as many as five VCF Instances, but uses more resources than the embedded model, which runs inside the management vCenter.
- Azure Relay
Messaging service connecting cloud and on-premises endpoints through outbound connections on port 443, without a VPN, inbound ports or VNet routing. The on-premises data gateway and App Service Hybrid Connections rely on it.
- Azure Virtual Machines for deployment
Access policy option on a Key Vault (enabled-for-deployment) that permits Microsoft.Compute to pull certificates, kept as secrets, into VMs at creation time. Azure Disk Encryption doesn't rely on this setting.
- BIOS
Generation 2 Hyper-V machines use UEFI with Secure Boot; Generation 1 machines rely on this older firmware.
- BitLocker
Encrypts entire Windows volumes. Nutanix Move neither detects it on source VMs nor carries vTPM data across, so plan a separate route to the keys; on AHV it can rely on a vTPM if Secure Boot is on.
- Client credentials
App-only OAuth 2.0 flow in which the application signs in as itself, not on behalf of a user; daemons, service-to-service calls and managed identities rely on it.