22. A system comprising: a data processing apparatus; and a computer storage medium encoded with a computer program, the program comprising data processing apparatus instructions that when executed by the data processing apparatus cause the data processing apparatus to perform operations comprising: providing to a client device a search resource including interface instructions that cause the client device to generate a search interface that includes a query input field; receiving a query input from a client device, the query input having been input into the query input field and being one or more characters in a first input sequence constituting one or more words in a second input sequence; in response to receiving data indicating a determination that the query input received from a client device does not meet a query suggestion threshold: selecting a query input sequence from the query input, the query input sequence being up to a word n-gram of the most subsequent words of the one or more words in the second input sequence; determining a likelihood that the query input sequence terminates at a word boundary from a word boundary count and a non-word boundary count associated with a query sequence key matching the query input sequence; and providing search results responsive to the client device at the expiration of a providing time delay that is based on the determined likelihood.
22. A system comprising: a data processing apparatus; and a computer storage medium encoded with a computer program, the program comprising data processing apparatus instructions that when executed by the data processing apparatus cause the data processing apparatus to perform operations comprising: providing to a client device a search resource including interface instructions that cause the client device to generate a search interface that includes a query input field; receiving a query input from a client device, the query input having been input into the query input field and being one or more characters in a first input sequence constituting one or more words in a second input sequence; in response to receiving data indicating a determination that the query input received from a client device does not meet a query suggestion threshold: selecting a query input sequence from the query input, the query input sequence being up to a word n-gram of the most subsequent words of the one or more words in the second input sequence; determining a likelihood that the query input sequence terminates at a word boundary from a word boundary count and a non-word boundary count associated with a query sequence key matching the query input sequence; and providing search results responsive to the client device at the expiration of a providing time delay that is based on the determined likelihood. 23. The system of claim 22 , wherein the word boundary counts and non-word boundary counts are determined from an analysis of query logs storing queries, each query being one or more characters in a first sequence constituting one or more words in a second sequence.