Optimized Row Columnar (ORC), an Apache column-oriented format that stores indexes and statistics inside the file. You can use it with Auto Loader and external tables but not with managed tables.
Also called Optimized Row Columnar.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains ORC in context, with comparison tables and the common traps.
Terms in this definition
- LAMP
Short for Linux, Apache, MySQL and PHP (Perl and Python also fill the P): a widely used open-source stack for web applications whose database is frequently Azure Database for MySQL.
- FORMAT
A DAX function that turns a value into text according to a format string, for instance "MMMM" to show a month's name. Since the output is text, numeric operations can't use it, and dynamic format strings were introduced to get around that.
- Statistics
Information about how values are distributed in a column, which the warehouse optimiser uses to estimate plan costs. Fabric builds and updates it for you; manual CREATE, UPDATE and DROP STATISTICS are limited to single-column histograms.
- Auto Loader
The
cloudFilesStructured Streaming source, which picks up new files from cloud storage or volumes as they arrive. Its checkpoint records progress so each file is processed exactly once, and it can infer and evolve the schema. - External
API Management virtual network mode in which the gateway stays public but can call private back ends inside the VNet.
Related terms
- read_files
A SQL table-valued function that loads files in formats such as CSV, JSON, XML, Parquet, Avro, ORC, text or binary and infers their schema to return rows. Used with the
STREAMkeyword inside a streaming table, it relies on Auto Loader.