Archive: DeRef Reference

Mon, 01 Jan 0001 00:00:00 +0000

This reference provides complete syntax and usage information for this.DeRef() in incremental SQL models.

Overview

this.DeRef() references other models, creates dependency relationships, and enables incremental processing by referencing previous materializations.

Parameter reference

Parameter	Type	Description
`dependency`	String	Specifies the dependency type: `"normal"`: Mandatory `"optional"`: Use if exists `"coercive"`: Prefer to create Default: `"normal"`
`pre_existing`	Boolean	When `true`, references a previous materialization of the model (typically the current model itself for incremental processing). Should be used with `dependency="optional"` and `checkpoint_name` to specify the baseline context. Default: `false`
`prereqs`	Array	Prerequisites that must be met before referencing. Use `.Except()` for negative prerequisites Default: `[]`
`baseline_name`	String	Baseline context name for incremental processing (must match `checkpoint_name`). Used when referencing delta models to specify which baseline checkpoint to use for delta computation. Default: `""`
`checkpoint_name`	String	Checkpoint name for context management. When using `pre_existing=true`, this names the checkpoint context for referencing previous materializations. Default: `""`
`time_grain_spec`	String	Time grain: `"hourly"`, `"daily"`, `"weekly"`, `"monthly"`, `"yearly"` Default: `""`
`skip_dependency`	Boolean	Skip dependency registration Default: `false`
`contract`	Contract object	Contract specification for model validation Default: `null`

Returned object methods

The object returned by this.DeRef() provides these methods:

Method	Description
`.IsEnabled()`	Returns `true` if the model is enabled and available. Returns `false` if `IsNil()` is `true` or if enablement status is not `enabled=true`. Prefer using `.IsEnabled()` in conditions to check if a model is available.
`.IsNil()`	Returns `true` if the checkpoint itself wasn’t found. This is a structural check for missing checkpoints and is rarely used.
`.Except()`	Creates a negative prerequisite. Use in `prereqs` to proceed only when the model does not exist.

Usage

This section explains some common usage patterns for this.DeRef().

Basic model reference

{% with users = this.DeRef("inputs/users") %}
 SELECT * FROM {{ users }}
{% endwith %}

Optional dependency

Use dependency="optional" when the model may not exist. You can check if the model is enabled using .IsEnabled() method:

{% with optional_model = this.DeRef("models/optional_feature", dependency="optional") %}
 {% if optional_model.IsEnabled() %}
 SELECT * FROM {{ optional_model }}
 {% else %}
 SELECT 'Feature not available' as status
 {% endif %}
{% endwith %}

Reference with contract

{% set contract = BuildContract('{"is_event_stream": false, "with_columns":[{"name":"user_id"}]}') %}
{% with events = this.DeRef("inputs/events", contract=contract) %}
 SELECT user_id, COUNT(*) as event_count
 FROM {{ events }}
 GROUP BY user_id
{% endwith %}

Incremental SQL model pattern

The standard pattern for incremental SQL models is shown:

{%- set rootIncrementalPreReqs = this.RootIncrementalPreReqs() -%}
{%- set lastThis = this.DeRef(pre_existing=true, dependency="optional", checkpoint_name="baseline", prereqs=rootIncrementalPreReqs) -%}

{% set events_delta = this.DeRef("inputs/events/incr_delta_tbl", dependency="coercive", baseline_name="baseline", prereqs=[lastThis]) %}

{% set events_full = this.DeRef("inputs/events", prereqs=[events_delta.Except()]) %}

{# All DeRef before this line. Note that DeRef should not be put in conditionals. DeRef mark dependencies — use prereqs for conditional dependencies #}

{% if lastThis %}
 -- Incremental mode: merge with baseline
 SELECT * FROM {{ lastThis }}
 UNION ALL
 SELECT * FROM {{ events_delta }}
{% else %}
 -- Full refresh mode: process all data
 SELECT * FROM {{ events_full }}
{% endif %}

How it works

lastThis: References the previous materialization using pre_existing=true. Returns nil if no baseline exists.
events_delta: Delta table (new data since baseline). Only enabled when lastThis exists (via prereqs=[lastThis]). Uses baseline_name to specify which baseline checkpoint to compare against.
events_full: Full input table. Only enabled when events_delta does NOT exist (via prereqs=[events_delta.Except()]).
Conditional logic: If lastThis exists, merge with delta; otherwise, process full data.

Tip: Always declare all this.DeRef() calls together at the top of your template, not inside conditionals. Use prereqs to chain conditional evaluation instead.

Prerequisites for conditional dependencies

-- Ensure specific models exist before referencing
{{ this.DeRef("models/target", prereqs=[model1, model2]) }}

-- Negative prerequisite - only proceed if specified model does NOT exist
{% set deltaInputVarTable = this.DeRef("inputs/events/incr_delta_tbl/var_table", dependency="optional") %}
{{ this.DeRef("inputs/events/var_table", prereqs=[deltaInputVarTable.Except()]) }}

For is_append_only input models, Profiles automatically creates delta models at /path/to/input/incr_delta_tbl. Prerequisites determine the SQL generation strategy based on the availability of these incremental artifacts.

See more

Incremental SQL Models: Overview of incremental SQL models
Checkpoints and Baselines: Understand checkpoints and baselines
How to Make Features Incremental: Step-by-step guide to convert features to incremental

RudderStack Docs – Incremental SQL Models

Archive: DeRef Reference

Overview

Parameter reference

Returned object methods

Usage

Basic model reference

Optional dependency

Reference with contract

Incremental SQL model pattern

Prerequisites for conditional dependencies

See more