openglacier

The OpenGlacier Modeling Language

Reference and guide to the language of openglacier: og-core, its daemon ogd, the glacierdb distribution, and the Places and views built on them.

Edition of 25 October 2026

About this book

The OpenGlacier Modeling Language (OGML in this book) is one language for three jobs:

querying: reading documents, filtering, computing, joining, aggregating;
writing: inserting, updating, deleting and bulk-loading documents in one transaction;
modeling: naming queries as views, stacking views into a data model, and keeping the costly ones materialized.

A query is a pipeline. It names a source, then sends its rows through stages separated by |:

on orders
| where status == "paid"
| derive revenue = price * qty
| group | by region | sum revenue | end
| sort revenue desc

How this book is organized

Part	What it holds	Read it when
Guide	What the language is for, and a tour of it in examples	You are new to OGML
Language	The rules every query follows: tokens, values, expressions, the shape of a query, parameters, history	You write queries by hand
Stage reference	One entry per stage: definition, syntax, behavior, examples, errors	You need the exact form of a stage
Function reference	One entry per function: signature, result, edge cases, examples	You compute values
Modeling	Views, materialized views, caches, patterns for building a data model	You design a data model
Running queries	How queries execute, memory bounds, system collections, statistics, errors, the request	You tune or debug
Appendices	Cookbook, full grammar, quick reference, limits, and the index	Any time

Each reference entry follows the same layout:

Definition: one sentence.
Syntax: the accepted forms, with <placeholders> and [optional parts].
Behavior: what it does, row by row, including the edge cases.
Examples: queries with their results.
Errors and limits: what it refuses, and why.
See also: related stages and functions.

Conventions

Queries are shown in text blocks. Results are shown as JSON, one document per line, without _id unless it matters.
-- … after a query line is a comment of this book, not of the language (OGML has no comments).
<name> is a placeholder; [ … ] is optional; a | b in a syntax line means one of, except where the pipe is the stage separator (it then stands at the start of a line).
The examples read the three small collections below.

users     { name, age, city, active, tags: [...], profile: { country, score } }
orders    { order_id, user, product, qty, price, status, month, region }
products  { code, label, category, embedding: [x, y, z] }

users	age	city	active	tags	profile.country	profile.score
Alice	31	Paris	true	admin, dev	FR	9.5
Bob	17	Lyon	false	dev	FR	7
Carol	45	Berlin	true	(empty)	DE	8.25
Dan	28	Paris	true	ops	FR	6

orders	user	product	qty	price	status	month	region
1	Alice	P1	2	10.0	paid	2026-01	EU
2	Alice	P2	1	99.5	paid	2026-02	EU
3	Bob	P1	5	10.0	pending	2026-01	EU
4	Carol	P3	1	250.0	paid	2026-02	US
5	Dan	P2	3	99.5	cancelled	2026-01	US
6	Carol	P1	4	10.0	paid	2026-01	US

products	label	category	embedding
P1	Pen	office	[1.0, 0.0, 0.0]
P2	Printer	office	[0.9, 0.1, 0.0]
P3	Phone	mobile	[0.0, 1.0, 0.0]

Sources of truth

This book follows the engine. Where they disagree, the engine wins and the book has a bug:

the stage catalogue, og-core/src/query/stage.rs (also listed live by the .query.stages operation);
the function table, og-core/src/query/eval.rs (Function);
the views, og-core/src/view.rs;
the developer reference, og-core/src/query/README.md.

To read the book as a website: mdbook serve og-books/manifest/the_ogml_language. The Markdown files also read as they are.

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The OpenGlacier Modeling Language

About this book

How this book is organized

Conventions

Sources of truth