Jargon: CockroachDB words for newcomers

SEO: glossary, terms, vocabulary, dictionary

Focusing here on those words you won't find otherwise explained on our blog. Why?

  • you want to understand the chatter between devs

  • you're an external contributor to CockroachDB and want to ensure you're not missing anything

  • if you're just starting at Cockroach Labs

  • if you've been at Cockroach Labs for a while but somehow you missed an explanation and you're too afraid to ask

If you wish to have some more words explained, just ask!

The definitions should be given in Simple English. If you find them difficult to understand, ask to clarify!

  • aggregation: an operation that a client app can perform in SQL to simplify a lot of data into a simple result (e.g. counting)

  • Aphyr: the usual name Kyle Kingsbury goes by

  • AWS (Amazon Web Services): Amazon's Cloud hosting

  • Azure: Microsoft's Cloud hosting

  • Bikeshed: many engineers spending a lot of time debating a minor issue - see the story here

  • BSL: Business Source License, a license applied to part of our codebase. Code licensed under the BSL becomes automatically re-licensed under the Apache License (open source) after 3 years. See also CCL.

  • CalVer: calendar versioning scheme for CockroachDB. See here for details.

  • Cassandra: another DB product we hear about often

  • CC: CockroachCloud

  • CCL: Cockroach Community License, a license applied to part of our codebase that corresponds to “Enterprise” features. See also BSL.

  • CDC: acronym for “Change Data Capture”. CockroachDB’s version of change feeds, see definition below.

  • Change feeds: a way for a user to ask the database to ping the user (or an app, i.e. a 3rd party) back when some data changes. The changed data is notified to the 3rd party (usually) asynchronously, i.e. possibly not atomically with the transaction where the change occurs. See also "Trigger".

  • Chaos: testing method that stops nodes in a test cluster unpredictably

  • Chaos monkey: program that performs chaos testing

  • CI (Continuous integration): program that runs tests and produces reports automatically in the background

  • Cloud: someone else's computer

  • Cluster: An ambiguous term, especially in the context of CockroachCloud. Generally, one of:

    • [CRDB/Cockroach/CockroachDB] Cluster: one deployment of CockroachDB, a group of one or more nodes (servers)

    • [Kubernetes] Cluster: A group of one or more Kubernetes nodes, usually including a leader node.

    • [CC/CockroachCloud] Cluster: One or more Kubernetes Clusters running a single deployment of CockroachDB

    • [Host/Serverless] Cluster: One deployment of CockroachDB, usually on Kubernetes, that contains many Tenants.

  • CockroachCloud: a hosting service provided by CRL, where CRL runs CockroachDB clusters on behalf of customers.

  • Code review: A process by which a second (or more) engineer reviews code before it is merged into the main codebase. At CRL, every code must be reviewed, and approved (see LGTM).

  • Code yellow: moving an issue to top company priority (idea comes from Google). During a code yellow, any task pertaining to the code yellow takes precedence over non code yellow related tasks.

  • CRL: acronym for Cockroach Labs

  • Cutting the release: selecting one particular version of the product to publish out

  • Data sovereignty: the demand for some apps/companies to have data located in specific places geographically, for example in EU data for citizens must be hosted in the EU

  • DDL (Data Definition Language): the part of SQL that apps can use to manage tables and indexes (the schema), e.g. create/rename/delete them. This includes e.g. "CREATE TABLE" but does not include "SELECT". See also "DML."

  • Delta: an incremental change, such as between git commits or incremental backups.

  • Denormalization: An explicit copy of some normalized data in a different format, in order to enable faster access. "Denormalized data" = indexes, materialized views, etc. --- all the stuff that copies "base" data into a different format for speed on operations that aren't by primary key.

  • DML (Data Manipulation Language): the part of SQL that apps can use to read and write data, e.g. query tables or update table rows. This includes e.g. "SELECT" or "INSERT" but does not include "CREATE TABLE". See also "DDL."

  • Encryption at rest: have the data encrypted in the database, not only when queried by clients

  • GCE (Google Compute Engine): Google's Cloud hosting

  • Geospatial index: An index that is efficient for storing 2d coordinates (such as lat/long) such that two points on the coordinate system that are close on the (lat/long) map are stored relatively close together in the index ordering. The uniqueness of the Geospatial index is in maintaining the "closeness" when going down from 2 dimensions (lat/long) to one dimension (the index). Usually achieved with a space filling curve

  • GIS (Geographical Information System): A system optimized for geographical data, makes heavy use of geospatial indexes, but also spatial-temporal indexes (combination of geospatial data and time series data), and also can understand and digest data stored in standard formats used for geographic data.

  • Git: a tool and database to store and share source code

  • SH (self-hosted): CockroachDB cluster(s) is hosted directly by the customer; cf., CockroachCloud

  • HTAP: Hybrid Transactional/Analytical Processing. I.e. OLAP + OLTP.

  • Index: A copy of some parts of a database table, ordered to make lookups very quick according to the index columns. There is always a "primary index", ordered by primary key, making lookups of a row if you know the primary key very fast. Other indexes are called "secondary indexes", and are ordered by some other criteria (could be some other columns, or even combinations of columns, or even combinations of columns from different tables). An index is a denormalization.

  • Jepsen: a tool that tests databases in a harsh way, made by Aphyr; also the name of Aphyr's blog about database testing

  • LGTM: Short for "looks good to me", the typical way one says they approve of a PR at the end of a code review, okaying it for merge. LGTM doesn't necessarily mean you can hit the merge button, for instance "LGTM, if you fix XYZ" still means XYZ should be done. They are just trusting you to do so, and don't necessarily need to verify that (if XYZ is trivial).

  • LSM: Log Structured Merge Tree, a data structure used by Pebble/CRDB (as well as RocksDB and others) for organizing storage on disk. Alternative to the B+ trees traditionally used in databases. A large topic, read more here or on Wikipedia.

  • Materialized view: a SQL view where the data of the view is duplicated from the original table (As opposed to a simple/dematerialized view, where a query on the view is automatically translated to a query on the underlying table). Materialized views are useful when the query that creates the view is complex and the views is used more often than the data is changed, because it then saves SQL execution time for the clients using the view.

  • Merge: the action of accepting a PR to the main product

  • Merge skew: An error condition encountered by the entire team when two changes on the git repository get merged concurrently and the result of both changes together causes CockroachDB to break. We use the ‘bors’ merge automation bot to prevent concurrent merges and thus merge skews. Merge skews can also be avoided by a healthy regimen of regularly rebasing, i.e. re-creating the patches on top of the latest git revision.

  • Mongo: short for MongoDB, another DB product we hear about often

  • Multi-tenant CockroachDB: an extension of the base CockroachDB architecture where multiple customers (“tenants”) can use the same CockroachDB cluster safely. A Multi-tenant cluster has two kinds of “nodes”: KV nodes that store the data for all tenants, and SQL nodes that are specific to each tenant.

  • MVCC: Multi-Version Concurrency Control. We use it in CockroachDB. A large topic in database concurrency models, see our docs or read more on Wikipedia.

  • Node: (CockroachDB node) one instance of a CockroachDB server process, that stores part of the data in an entire CockroachDB cluster. A single cluster can have many nodes. In a serverless (multi-tenant) cluster, we don’t use the word “node” alone and instead specify “KV node” or “SQL pod”.

  • Node.js: a Javascript library that makes it easier to write server programs in Javascript. Completely unrelated to the notion of CockroachDB node.

  • Normalization: Normalization refers to the process of reducing copies of data as much as possible so that there aren't too many logical copies of the same information (as that would increase the possibility of errors if some copies are updated without updating all copies). See wikipedia. Usually contrasted with explicit denormalization.

  • OLAP (Online Analytics Processing): a class of applications where the most common queries are long and touch most of the data at a time with complex computations -- contrast with OLTP

  • OLTP (Online Transaction Processing): a class of applications where the most common queries are short and touch a bit of data at a time with simple computations -- contrast with OLAP

  • ORM (Object-Relational Mapping): a piece of software used by an app to access a DB

  • Pebble: CockroachDB’s storage engine, an embedded key-value store based on RocksDB. See our blog post.

  • PR (Pull Request): a proposal for a change to the source code submitted for review to colleagues. See "merge"

  • Production monkey: person deploying new versions and maintaining test clusters. Usually rotates and a rotation lasts a week, to encourage all engineers to be familiar with running a full cluster.

  • Range: a logical portion of the data in a DB. In other distributed databases called a "shard", "chunk", or "tablet". Each range can have multiple physical copies, on different nodes. Each copy is called a “replica”.

  • Rebase: Take a git commit (the set of line-by-line changes) and apply those deltas to a different commit. Usually done because "master" moved on while you were working on a change, and now your commit won't merge cleanly. Usually a good habit to do before merging anyway, as not all conflicts are caught by git. See "merge skew".

  • Reg cluster: short for "registration cluster", a CockroachDB cluster ran by CRL internally to store telemetry data sent by customers.

  • Reg server: an internet microservice ran by CRL that receives telemetry data sent by customers.

  • Replication factor: how many copies there are of each Range in a DB or Zone. Default is 3.

  • Replica: one of the copies of some Range in a DB or Zone. There are replication factor replicas of a range across a cluster.

  • RFC: Short for "Request for comments". An RFC is a description of a larger change, written to outline why the change, what the change will consist of, etc. before the code is written. Used to build consensus around a code, before diving into writing code for weeks. This lets issues/thoughts get surfaced early, so that time is not wasted writing code, only to discover in a code review that there was a much better way to do things, if only, say, the author had requested some comments on their thoughts before diving off.

  • SemVer: semantic versioning scheme, which we used previously for CockroachDB. Now using calver instead.

  • Server: something running in the backend of a client-server architecture. We don’t like the word “server” too much at CRL because it is very ambiguous. It can designate too many things! We have CockroachDB “servers” (KV nodes and SQL pods), CockroachCloud “servers” (monitoring, console, orchestration), testing “servers” etc.

  • Serverless: inside CockroachLabs, the name of a project that integrates Multi-Tenant CockroachDB inside CockroachCloud. Outside CRL, it’s a design philosophy that tries to make end-users blind to the existence of servers.

  • SH: often refers to self-hosted customers

  • Spanner (Google product): another project we get inspiration from

  • SRE: Site Reliability Engineer - a discipline that incorporates aspects of software engineering and applies them to infrastructure and operations problems, with the goal of creating scalable and reliable software systems

  • Team City: one of our continuous integration tools

  • Time series: a way to organize data in a DB where the data is organized primarily by time; commonly used to store events over time; sometimes subject to OLAP applications

  • TPC-C: a database benchmark developed in 1992 to simulate a traditional OLTP application (i.e. wholesale distributor w/ warehouses and retail locations). See also TPC-E.

  • TPC-E: a database benchmark developed in 2007 to simulate a more modern OLTP application (i.e. a stock brokerage w/ fluctuating stock prices and many concurrent orders). See also TPC-C.

  • Trigger: a way for a user to ask the database to ping the user (or an app) back when some data changes, or run a stored procedure on the server. The trigger (usually) happens before the transaction commits, so that the consumer can see the changes atomically. See also "Change feed".

  • YCSB: Yahoo Cloud Serving Benchmark, designed to measure NoSQL and other cloud service databases.

  • Zone config/zones: CockroachDB way to set different configuration parameters to different parts of a cluster, can be used to set constraints on replication (e.g. at least one copy must be on a different continent) or for data sovereignty (e.g. no copies of this data should reside outside EU territory)