Apache Solr Reference Guide Covering Apache Solr 6.0

Analysis Phases
Analysis takes place in two contexts. At index time, when a field is being created, the token stream that results
from analysis is added to an index and defines the set of terms (including positions, sizes, and so on) for the
field. At query time, the values being searched for are analyzed and the terms that result are matched against
those that are stored in the field's index.
In many cases, the same analysis should be applied to both phases. This is desirable when you want to query
for exact string matches, possibly with case-insensitivity, for example. In other cases, you may want to apply
slightly different analysis steps during indexing than those used at query time.
If you provide a simple definition for a field type, as in the examples above, then it will be used for
both indexing and queries. If you want distinct analyzers for each phase, you may include two defi
nitions distinguished with a type attribute. For example:
In this theoretical example, at index time the text is tokenized, the tokens are set to lowercase, any that are not
listed in keepwords.txt are discarded and those that remain are mapped to alternate values as defined by the
synonym rules in the file syns.txt. This essentially builds an index from a restricted set of possible values and
then normalizes them to values that may not even occur in the original text.
At query time, the only normalization that happens is to convert the query terms to lowercase. The filtering and
mapping steps that occur at index time are not applied to the query terms. Queries must then, in this example, be
very precise, using only the normalized terms that were stored at index time.
Analysis for Multi-Term Expansion
In some types of queries (ie: Prefix, Wildcard, Regex, etc...) the input provided by the user is not natural
language intended for Analysis. Things like Synonyms or Stop word filtering do not work in a logical way in these
types of Queries.
The analysis factories that can work in these types of queries (such as Lowercasing, or Normalizing Factories)
are known as MultiTermAwareComponents. When Solr needs to perform analysis for a query that results
in Multi-Term expansion, only the MultiTermAwareComponents used in the query analyzer are used, Factory
that is not Multi-Term aware will be skipped.
For most use cases, this provides the best possible behavior, but if you wish for absolute control over the
analysis performed on these types of queries, you may explicitly define a multiterm analyzer to use, such as in
the following example:
Apache Solr Reference Guide 6.0
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