TSBS Supplemental Guide: MongoDB

July 3, 2018 ยท View on GitHub

MongoDB is a general NoSQL database that stores data as JSON-like documents. This supplemental guide explains how the data generated for TSBS is stored, additional flags available when using the data importer (tsbs_load_mongo), and additional flags available for the query runner (tsbs_run_queries_mongo). This should be read after the main README.

Data format

Data generated by tsbs_generate_data for MongoDB is serialized as a FlatBuffer to represent each reading. This format is not (easily) human readable in its serialized format, however the FlatBuffer is specified as follows:

// mongo.fbs
namespace serialize;
table MongoTag {
  key:string;
  value:string;
}

table MongoReading {
  key:string;
  value:double;
}

table MongoPoint {
  measurementName:string;
  timestamp:long;
  tags:[MongoTag];
  fields:[MongoReading];
}

root_type MongoPoint;

tsbs_load_mongo Additional Flags

-url (type: string, default: localhost:27017)

URL for connecting to the MongoDB server daemon.

-write-timeout (type: duration, default: 10s)

Length of the timeout for writes. It is expressed as a Golang time.Duration string, meaning a number followed by a unit abbreviation (s = seconds, m = minutes, h = hours), e.g., the default 10s is ten seconds.

Miscellaneous

-document-per-event (type: boolean, default: false)

Store each data reading as a separate document instead of the default aggregated format. The default aggregated format stores an hour's worth of readings for a particular device in one document and uses updates for a more efficient storage model. However for testing or comparing, this flag is provided to use a model where each data reading is stored as a single document.

tsbs_run_queries_mongo Additional Flags

-url (type: string, default: localhost:27017)

URL for connecting to the MongoDB server daemon.

-read-timeout (type: duration, default: 10s)

Length of the timeout for reads. It is expressed as a Golang time.Duration string, meaning a number followed by a unit abbreviation (s = seconds, m = minutes, h = hours), e.g., the default 10s is ten seconds.