---
title: "Optimising the performance of filter expressions"
slug: "filtering-performance"
tags: ["filter", "performance"]
updated: 2024-08-19T12:51:30Z
published: 2024-08-19T12:51:30Z
canonical: "support.lusid.com/filtering-performance"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://support.lusid.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Optimising the performance of filter expressions

When you retrieve data from LUSID you can typically [filter the result set](/v1/docs/filtering-information-retrieved-from-lusid) to qualify the data returned.

For example, the following call to the `ListInstruments` API applies a filter expression of `name startswith 'App'` to retrieve just those instruments with 'App…'-like names:

```json
curl -X GET "https://<your-domain>.lusid.com/api/api/instruments?filter=name%20startswith%20%27App%27" 
  -H "Authorization: Bearer <your-API-access-token>"
```

> **Note**: There is a maximum URL length of 2048 characters that may impact the complexity of any filter expression you submit via the LUSID API. This restriction does not apply if you filter LUSID data using Luminesce.

As you can see from the table below, the slowest filter expressions are those that join multiple expressions together using the `or` operator. Note that other factors less easy to tabulate may also affect performance, such as the size of your LUSID dataset and the number of filter expressions you choose to join using either `and` or `or`.

| **Speed** | **Entity attribute to filter on** | **Filter operator** | **Example** |
| --- | --- | --- | --- |
| Faster | Fields and nested fields | `eq` | `name eq 'BP'` |
|  | Identifiers | `identifiers['Isin'] eq 'GB0007980591'` |
| SHKs (portfolios only) | `subholdingkeys[Transaction/Demo/Strategy] eq 'Income'` |
| Single-value properties | `properties[Instrument/Ibor/Industry] eq 'Energy'` |
| Custom data fields (custom entities only) | `fields['Address'] eq '1 Main Street'` |
| Multi-value properties | `properties[Instrument/Ibor/Industry] all (~&nbsp;eq 'Energy')` |
| Relationships (supported entities only) | `relationships any (Instrument.name eq 'BP')` |
| As above, in the same order | `gt` `gte` `lt` `lte` `startswith` `in` | `name startswith 'BP'` |
| As above, in the same order | `exists` `neq` `not exists` `not in` | `name neq 'BP'` |
| As above, in the same order | `and` | `name eq 'BP' and domCcy eq 'GBP'` |
| Slower | As above, in the same order | `or` | `name eq 'BP' or domCcy eq 'GBP'` |