AQL Archives

AQL optimizer improvements for 2.8

January 20, 201600PerformanceTags: AQL, Performance, Release

With the 2.8 beta phase coming to an end it’s time to shed some light on the improvements in the 2.8 AQL optimizer. This blog post summarizes a few of them, focusing on the query optimizer. There’ll be a follow-up post that will explain dedicated new AQL features soon. Read more

AQL Function Speedups in 2.8

December 4, 201500PerformanceTags: AQL, Performance, Release

While working on the upcoming ArangoDB 2.8, we have reimplemented some AQL functions in C++ for improved performance. AQL queries using these functions may benefit from using the new implementation of the function.

The following list shows the AQL functions for which a C++ implementation has been added in 2.8. The other C++-based AQL function implementations added since ArangoDB 2.5 are also still available. Here’s the list of functions added in 2.8: Read more

Using Multiple Indexes Per Collection

December 1, 201503Documentation, PerformanceTags: AQL, Performance

The query optimizer in ArangoDB 2.8 has been improved in terms of how it can make use of indexes. In previous versions of ArangoDB, the query optimizer could use only one index per collection used in an AQL query. When using a logical OR in a FILTER condition, the optimizer did not use any index for the collection in order to ensure the result is still correct.

This is much better in 2.8. Now the query optimizer can use multiple indexes on the same collection for FILTER conditions that are combined with a logical OR. Read more

Index Speedups in 2.8

November 27, 201501PerformanceTags: AQL, Performance, Release

The upcoming 2.8 version of ArangoDB will provide several improvements in the area of index usage and query optimization.

First of all, hash and skiplist indexes can now index individual array values. A dedicated post on this will follow shortly. Second, the query optimizer can make use multiple indexes per collection for queries with OR-combined filter conditions. This again is a subject for another post. Third, there have been some speed improvements due to changes in the general index handling code. This is what this post is about. Read more

Using Bind Parameters in the AQL Editor

November 20, 201500API, GeneralTags: AQL

The AQL editor in the web interface is useful for running ad hoc AQL queries and trying things out. It provides a feature to explain the query and inspect its execution plan. This can be used to check if the query uses indexes, and which.

So far the AQL editor only supported using query string literals, but it lacked support for bind parameters. Queries issued by application code however often will use bind parameters for security reasons. Often enough this prevented copying & pasting queries from the application code into the AQL editor and vice versa without making manual adjustments. Read more

GA of ArangoDB 2.7 – Big + for Indexes, Throughput, AQL and Foxx

October 12, 201500GeneralTags: AQL, Foxx

Long awaited and now we´ve finished it! New major release of ArangoDB 2.7 is ready for download. First of all a big thanks to our community for your great support! We´ve implemented a lot of your ideas! After your feedback to RC1 and RC2 we are happy to bring a new major release to the world. With ArangoDB 2.7 we increased our performance even further and improved query handling a lot. Read more

On building AQL Query Strings

August 31, 201500Query Language, SecurityTags: AQL

I recently wrote two recipes about generating AQL query strings. They are contained in the ArangoDB cookbook by now:

After that, Github user tracker1 suggested in Github issue 1457 to take the ES6 template string variant even further, using a generator function for string building, and also using promises and ES7 async/await.

We can’t use ES7 async/await in ArangoDB at the moment due to lacking support in V8, but the suggested template string generator function seemed to be an obvious improvement that deserved inclusion in ArangoDB.

Basically, the suggestion is to use regular JavaScript variables/expressions in the template string and have them substituted safely.

With regular AQL bind parameters, a query looks like this:

1

2

3

4

5

6

var bindVars = { name: "test" };

var query = `FOR doc IN collection

FILTER doc.name == @name

RETURN doc._key`;

db._query(query, bindVars);

This is immune to parameter injection, because the query string and the bind parameter value are passed in separately. But it’s not very ES6-y.

More info

AQL object literal simplification

July 28, 201500Query LanguageTags: AQL

ArangoDB’s devel branch recently saw a change that makes writing some AQL queries a bit simpler.

The change introduces an optional shorthand notation for object attributes in the style of ES6’s enhanced object literal notation.

For example, consider the following query that groups values by age attribute and counts the number of documents per distinct age value:

1

2

3

4

FOR doc IN collection

COLLECT age = doc.age WITH COUNT INTO length

RETURN { age: age, length: length }

The object declaration in the last line of the query is somewhat redundant because one has to type identical attribute names and values:

1 2	RETURN { age: age, length: length }

In this case, the new shorthand notation simplifies the RETURN to:

1 2	RETURN { age, length }

In general, the shorthand notation can be used for all object literals when there is an attribute name that refers to a query variable of the same name.

It can also be mixed with the longer notation, e.g.:

1 2	RETURN { age, length, dateCreated: DATE_NOW() }

Sign up for ArangoDB Cloud