Search Data


This article introduces the datasets we maintain for search analyses: search_aggregates and search_clients_engines_sources_daily. After reading this article, you should understand the search datasets well enough to produce moderately complex analyses.

Table of Contents


Searches can be split into three major classes: sap, follow-on, and organic.

SAP searches result from a direct interaction with a search access point (SAP), which is part of the Firefox UI. These searches are often called SAP searches. There are currently 8 SAPs:

  • urlbar - entering a search query in the Awesomebar. Searches typed into the search bar in the middle of the browser window will also be recorded as urlbar searches.
  • urlbar_searchmode - selecting a search partner icon while entering a search query in the Awesomebar or tagging the search partner (i.e. @duckduckgo) before entering search query via Awesomebar (was formerly called alias added as of Firefox 64.)
  • searchbar - the main search bar (on the top right corner of browser window); not present by default for new profiles on Firefox 57+. Searchmode searches via the searchbar are logged as regular searchbar searches.
  • newtab - the search bar on the about:newtab page (not active in Firefox 92)
  • abouthome - the search bar on the about:home page (not active in Firefox 92)
  • contextmenu - highlight text, right click, and select "Search [search engine] for [highlighted text]" from the context menu.
  • system - starting Firefox from the command line with an option that immediately makes a search
  • webextension - initiated from a web extension (added as of Firefox 63)

Users will often interact with the Search Engine Results Page (SERP) to create "downstream" queries. These queries are called follow-on queries. These are sometimes also referred to as in-content queries since they are initiated from the content of the page itself and not from the Firefox UI.

For example, follow-on queries can be caused by:

  • Revising a query (restaurants becomes restaurants near me)
  • Clicking on the "next" button
  • Accepting spelling suggestions

Finally, we track the number of organic searches. These would be searches initiated directly from a search engine provider, not through a search access point.

Tagged vs Untagged Searches

Our partners (search engines) attribute queries to Mozilla using partner codes. When a user issues a query through one of our SAPs, we include our partner code in the URL of the resulting search.

Tagged queries are queries that include one of our partner codes.

Untagged queries are queries that do not include one of our partner codes. If a query is untagged, it's usually because we do not have a partner deal for that search engine and region (or it is an organic search that did not start from an SAP).

If an SAP query is tagged, any follow-on query should also be tagged.

Standard Search Aggregates

We report five types of searches in our search datasets: sap, tagged-sap, tagged-follow-on, organic, and unknown. These aggregates show up as columns in the search_aggregates and search_clients_engines_sources_daily datasets. Our search datasets are all derived from main_summary. The aggregate columns are derived from the SEARCH_COUNTS histogram.

The sap column counts all SAP (or direct) searches. sap search counts are collected via probes within the Firefox UI These counts are very reliable, but do not count follow-on queries.

In 2017-06 we deployed the followonsearch addon, which adds probes for tagged-sap and tagged-follow-on searches. These columns attempt to count all tagged searches by looking for Mozilla partner codes in the URL of requests to partner search engines. These search counts are critical to understanding revenue since they exclude untagged searches and include follow-on searches. However, these search counts have important caveats affecting their reliability. See In Content Telemetry Issues for more information.

In 2018, we incorporated this code into the product (as of version 61) and also started tracking so-called "organic" searches that weren't initiated through a search access point (sap). This data has the same caveats as those for follow on searches, above.

We also started tracking "unknown" searches, which generally correspond to clients submitting random/unknown search data to our servers as part of their telemetry payload. This category can generally safely be ignored, unless its value is extremely high (which indicates a bug in either Firefox or the aggregation code which creates our datasets).

In main_summary, all of these searches are stored in search_counts.count, which makes it easy to over count searches. However, in general, please avoid using main_summary for search analyses -- it's slow and you will need to duplicate much of the work done to make analyses of our search datasets tractable.

Outlier Filtering

We remove search count observations representing more than 10,000 searches for a single search engine in a single ping.

In Content Telemetry Issues

The search code module inside Firefox (formerly implemented as an addon until version 60) implements the probe used to measure tagged-sap and tagged-follow-on searches and also tracks organic searches. This probe is critical to understanding our revenue. It's the only tool that gives us a view of follow-on searches and differentiates between tagged and untagged queries. However, it comes with some notable caveats.

Relies on whitelists

Firefox's search module attempts to count all tagged searches by looking for Mozilla partner codes in the URL of requests to partner search engines. To do this, it relies on a whitelist of partner codes and URL formats. The list of partner codes is incomplete and only covers a few top partners. These codes also occasionally change so there will be gaps in the data.

Additionally, changes to search engine URL formats can cause problems with our data collection. See this query for a notable example.

Limited historical data

The followonsearch addon was first deployed in 2017-06. There is no tagged-* search data available before this.

default_private_search_engine is only available starting 2019-11-19.