Overview

BlueQL^TM is Skytable's own query language that very closely follows the design of SQL but with many modern features and superior security. This document explores a basic overview of BlueQL.

Design principles:

• Simplicity and clarity: The language shouldn't be overwhelming to understand
• Security with mandatory parameterization: We want to reduce the surface of injection attacks. For this reason, parameterization is mandatory.

Just like SQL, BlueQL has three categories of commands/queries inside it:

• DDL: Data definition language is used to define, modify and/or remove DDL objects such as spaces and models
• DCL: Data control language is used to control the access to data, and perform other administrative tasks
• DML: Data manipulation language is used to manipulate data

Jump to differences from SQL.

info

This text is not a detailed, formal guide. It's meant for developers and users who want to work with Skytable. If you need a more formal specification, like a grammar definition, please ask us, and we'll create it. We haven't published it yet because no one has requested it.

Identifiers

Can begin with any ASCII alphabet or an underscore (_) and then have any number of alphanumeric characters and/or underscores.

Keywords

Keywords are identifiers with special meanings and hence can't be used as identifiers in other places. Here's a full-list of keywords:

[
    "sysctl", "create", "alter", "drop", "use", "inspect", "describe", "insert", "select", "update",
    "delete", "exists", "table", "model", "space", "index", "type", "function", "rename", "add",
    "remove", "transform", "set", "return", "order", "sort", "group", "limit", "asc", "desc", "all",
    "by", "with", "on", "from", "into", "as", "to", "in", "of", "and", "or", "not", "if", "else",
    "where", "when", "allow", "auto", "default", "null", "transaction", "batch", "lock", "read",
    "write", "begin", "end", "key", "value", "primary", "truncate"
]

Data types

Boolean

A boolean value, either true or false

Unsigned integers

• uint8: unsigned 8-bit integer
• uint16: unsigned 16-bit integer
• uint32: unsigned 32-bit integer
• uint64: unsigned 64-bit integer

Signed integers

• sint8: signed 8-bit integer
• sint16: signed 16-bit integer
• sint32: signed 32-bit integer
• sint64: signed 64-bit integer

Floating point values

• float32: a single-precision float
• float64: a double-precision float

Simple collections

• binary: a binary blob represented as a sequence of uint8 values
• string: an UTF-8 string

Complex collections

• list: a list of any of the data types, including nested lists
  • A list is represented as: [] with values inbetween. For example, a list { type:string } would be represented as:

    ["sayan", "loves", "dogs"]
  • Lists cannot contain null values
  • List can be nested: You can have heavily nested lists like: [[[]], [["another one"]]]
  • List can only have one base type: This means that if you have a list like [[[string]]] each element must either be the same nested list, or an empty list

Note

New data types are frequently added, so treat this list as non-exhaustive.

Literals

• Null literal: null
• Numeric literals:
  • Unsigned: 1234
  • Signed: [-]1234
• Floating point literals: [-]1234.5678
• String literals: "hello"
• Binary literals: `binary`
• List literals: [..]
• Dictionaries: {<ident>: <literal>}

Literals are not available everywhere

It is very important for you to know that literals are not allowed everywhere. The only literals allowed everywhere are:

• Lists
• Dictionaries

Read below to understand why.

Parameters

All literals apart from dictionaries and lists must be used as parameters. BlueQL only allows literals as parameters. For example, using the Rust client, if you were to run this:

insert into myspace.mymodel('sayan', 'pass123', ['myfirstnote'])

You are required to parameterize the query like this:

use skytable::query;

let query = query!("insert into myspace.mymode(?, ?, [?])", "sayan", "pass123", "myfirstnote")

If you try to run it without any parameters (don't forget that skysh automatically parameterizes for convenience) the query won't even compile.

tip

Just so you know, parameterizing involves passing a separate parameter list, with each parameter encoded. You wouldn't need to worry about this because the client driver does all of that for you!

The question is why? The answer is security. SQL-injection vulernabilties have already costed companies a lot, so we don't want to inherit that from SQL.

Also, parameterization is exclusively possible for literals. This means that whenever you're accepting data from an untrusted source, it becomes a parameter. If you try to not use parameters, the query will not even compile.

On a final note, BlueQL doesn't support comments of any form also for security reasons.

Expressions

• +=: add RHS to LHS
  • Can be used outside arithmetic contexts
  • Add a char to a field mystring: mystring += ",world"
  • Add a list to a nested list field: mylist += ["item in nested list"]
• -=: subtract RHS from LHS
• /=: divide LHS by RHS
• *=: multiply LHS by RHS

DDL

Queries include:

• Spaces:
  • CREATE SPACE myspace [WITH { property: value, ... }]
  • ALTER SPACE myspace [WITH { property: updated_value, ... }]
  • DROP SPACE [allow not empty] myspace
• Models:
  • CREATE MODEL myspace.mymodel([primary] [null] field: field_type, ...) [WITH { property: value, ... }]
  • ALTER MODEL myspace.mymodel (ADD ... | UPDATE ... | REMOVE ...)
  • DROP MODEL [allow not empty] myspace.mymodel
• INSPECT GLOBAL: inspects global state, shows a list of spaces and users
• INSPECT SPACE <space>: inspects a single space, shows a list of models and other things
• INSPECT MODEL <model>: inspects a single model, shows information about stored data and other things

DML

• INSERT INTO myspace.mymodel(...)
• SELECT col1, ... FROM myspace.mymodel WHERE ...
• UPDATE myspace.mymodel SET counter += 1 WHERE ...
• DELETE FROM myspace.mymode WHERE ...

DCL

Queries include:

• SYSCTL REPORT STATUS: returns the status of the system. (Not a control query per se)
• SYSCTL CREATE USER "username" WITH { password: ... }: create a new user
• SYSCTL DROP USER "username": removes the user in question

Differences from SQL

• No literals (see above)
• Mandatory parameterization (see above)
• No semicolons!
• Only one statement per query. For multiple statements batches must be used
• DML queries are point queries (hence must contain a WHERE clause)