Directives

Directives are special instructions in conditional queries that modify how the query engine processes results. They are prefixed with # and can be used to control aspects such as including additional records before or after those that match a given condition.

The following directives are supported:

Operator	ReductStore Version	Description
#ctx_before	v1.16	Add additional records before each matching record as context, either by count or time window.
#ctx_after	v1.16	Add additional records after each matching record as context, either by count or time window.
#select_labels	v1.16	Retain only the specified labels in a record after filtering.
#ext	v1.17	Contains query parameters for extensions that process data during querying.

#ctx_before

The #ctx_before directive allows you to include extra records that occurred before each matching record. This is useful when you want context around a matched condition, such as to see what led up to it.

Syntax

{
  "#ctx_before": <expression as int> | <duration literal>
}

Behavior

• If the expression is an integer, it is interpreted as the number of records to include before each match.
• If the expression is a duration literal (e.g. "1s", "10m", "500ms"), it is interpreted as a time window to include records within that period before each match.

Examples

By number of records:

{
  "#ctx_before": 10
}

By time duration:

{
  "#ctx_before": "1h"
}

#ctx_after

The #ctx_after directive allows you to include extra records that occur after each matching record. This is useful when you want to examine consequences or outcomes following a detected condition.

Syntax

{
  "#ctx_after": <expression as int> | <duration literal>
}

Behavior

• If the expression is an integer, it is interpreted as the number of records to include after each match.
• If the expression is a duration literal, it is interpreted as a time window to include records within that period after each match.

Examples

By number of records:

{
  "#ctx_after": 5
}

By time duration:

{
  "#ctx_after": "30s"
}

#select_labels

The #select_labels directive allows you to filter the labels retained in each record after applying the query.

Syntax

{
  "#select_labels": [<label name 1>, <label name 2>, ...]
}

Behavior

This directive is applied after all other query processing, including context inclusion and filtering.

info

The #select_labels directive is ignored in replication conditional queries.

Example

{
  "#select_labels": ["temperature", "humidity"]
}

#ext

The #ext directive is used to specify parameters for extensions that process data during querying.

Syntax

{
  "#ext": {
    "<extension_name>": { <extension_parameters> }
  }
}

Behavior

The #ext directive allows you to pass configuration options to an extension that will process the data as part of the query. The specific parameters depend on the extension being used. Read more about the official extensions in the Extensions Documentation.

info

The #ext directive is ignored in replication conditional queries.

Example

{
  "#ext": {
    "select": {
      "columns": [{ "index": 0, "as_label": "speed" }]
    }
  }
}