Query autocompletions

A system, comprising:

• one or more computers programmed to perform operations comprising:
• receiving a query input in a search engine query input field in a user interface, before receiving an input expressly submitting the query input as a query to a search engine, the query input comprising multiple query terms;
• submitting the query input as a first query stem to an autocompletion module to obtain first query autocompletions;
• determining that the first query autocompletions do not satisfy a first quality test, and, in response, submitting a second query stem to the autocompletion module to obtain second query autocompletions, the second query stem being the first query stem with a prefix removed;
• receiving, from the autocompletion module, one or more second query autocompletions satisfying a second quality test, wherein the second quality test includes determining a ratio of a number of times a potential autocompletion occurs in a corpus of user queries to a number of times any query that includes the second query stem occurs in the corpus user queries, and comparing the ratio to a threshold value;
• and
• providing one or more second query autocompletions for presentation on the user interface.

A non-transitory computer storage medium encoded with a computer program, the computer program comprising instructions that when executed by data processing apparatus cause the data processing apparatus to perform operations comprising:

• receiving a query input in a search engine query input field in a user interface, before receiving an input expressly submitting the query input as a query to a search engine, the query input comprising multiple query terms;
• submitting the query input as a first query stem to an autocompletion module to obtain first query autocompletions;
• determining that the first query autocompletions do not satisfy a first quality test, and, in response, submitting a second query stem to the autocompletion module to obtain second query autocompletions, the second query stem being the first query stem with a prefix removed;
• receiving, from the autocompletion module, one or more second query autocompletions satisfying a second quality test, wherein the second quality test includes determining a ratio of a number of times a potential autocompletion occurs in a corpus of user queries to a number of times any query that includes the second query stem occurs in the corpus user queries, and comparing the ratio to a threshold value;
• and
• providing the one or more second query autocompletions for presentation on the user interface.

A computer-implemented method comprising:

• receiving a query input in a search engine query input field in a user interface, before receiving an input expressly submitting the query input as a query to a search engine, the query input comprising multiple query terms;
• submitting the query input as a first query stem to an autocompletion module to obtain first query autocompletions;
• determining that the first query autocompletions do not satisfy a first quality test, and, in response, submitting one or more shortened query stems to the autocompletion module to obtain shortened query autocompletions, each shortened query stem being the first query stem with one or more query terms removed;
• receiving from the autocompletion module, one or more shortened query autocompletions satisfying a second quality test, wherein the second quality test includes determining a ratio of a number of times a potential autocompletion occurs in a corpus of user queries to a number of times any query that includes the shortened query stem occurs in the corpus user queries, and comparing the ratio to a threshold value;
• collecting the shortened query autocompletions;
• and
• providing the shortened query autocompletions for presentation on the user interface.