Drop Event During Parsing

Drop event during parsing using the dropEvent() function

Query

flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1[/Filter/] 2[/Filter/] 3[/Filter/] result{{Result Set}} repo --> 1 1 --> 2 2 --> 3 3 --> result

logscale

parseJson()
| case { someField = "some_value"
| dropEvent(); * }
| parseTimestamp(field=@timestamp)

Introduction

The dropEvent() function can be used both during queries and within the parser pipeline. Depending on usage, the function has different behavior.

If used during parsing, the event is dropped and removed entirely from the query output, meaning that the event data will not be stored in LogScale. If used within normal searching, the dropEvent() function is simply an alias for false - it behaves the same as false.

The dropEvent() function is often used within parsers to drop events during parsing that do not need to be ingested. The following example shows how to filter events as part of a parser by matching a particular field value from being ingested.

Step-by-Step

Starting with the source repository events.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1[/Filter/] 2[/Filter/] 3[/Filter/] result{{Result Set}} repo --> 1 1 --> 2 2 --> 3 3 --> result style 1 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
parseJson()
```
Parses the incoming data to identify JSON values and converts them into a usable field.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1[/Filter/] 2[/Filter/] 3[/Filter/] result{{Result Set}} repo --> 1 1 --> 2 2 --> 3 3 --> result style 2 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
| case { someField = "some_value"
| dropEvent(); * }
```
Starts a case statement, with the first matching expression identifying a field value in the extracted JSON field from the returned results. Then drops the event. This has the effect of terminating the parsing for this event, as there is no more data to be processed.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1[/Filter/] 2[/Filter/] 3[/Filter/] result{{Result Set}} repo --> 1 1 --> 2 2 --> 3 3 --> result style 3 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
| parseTimestamp(field=@timestamp)
```
Parses the timestamp from the @timestamp field for all other events that do not match the JSON value.
Event Result set.

Summary and Results

This query is used to drop events at ingestion. When used within the parser pipeline, the dropEvent() is a simple and practical way of eliminating events during the parsing of incoming data.

Examples Library