Indexing Language Reference

This reference documents the full Vespa indexing language. If more complex processing of input data is required, implement a document processor.

The indexing language is analogous to UNIX pipes, in that statements consists of expressions separated by the pipe symbol where the output of each expression is the input of the next. Statements are terminated by semicolon and are independent of each other (except when using variables).

Find examples in the indexing guide.

Indexing script

An indexing script is a sequence of indexing statements separated by a semicolon (;). A script is executed statement-by-statement, in order, one document at a time.

Vespa derives one indexing script per search cluster based on the search definitions assigned to that cluster. As a document is fed to a search cluster, it passes through the corresponding indexing cluster, which runs the document through its indexing script. Note that this also happens whenever the document is reindexed, so expressions such as now must be thought of as the time the document was (last) indexed, not when it was fed.

You can examine the indexing script generated for a specific search cluster by retrieving the configuration of the indexing document processor. 

$ vespa-get-config -i search/cluster.<cluster-name> -n vespa.configdefinition.ilscripts

The current execution value is set to null prior to executing a statement.

Indexing statement

An indexing statement is a sequence of indexing expressions separated by a pipe (|). A statement is executed expression-by-expression, in order.

Within a statement, the execution value is passed from one expression to the next.

The simplest of statements passes the value of an input field into an attribute: 

input year | attribute year;

The above statement consists of 2 expressions; input year and attribute year. The former sets the execution value to the value of the "year" field of the input document. The latter writes the current execution value into the attribute "year".

Indexing expression

Primitives

A string, numeric literal and true/false can be used as an expression to explicitly set the execution value. Examples: "foo", 69, true).

Outputs

An output expression is an expression that writes the current execution value to a document field. These expressions also double as the indicator for the type of field to construct (i.e. attribute, index or summary). It is important to note that you can not assign different values to the same field in a single document (e.g. attribute | lowercase | index is illegal and will not deploy).

Expression Description
attribute Writes the execution value to the current field. During deployment, this indicates that the field should be stored as an attribute.
index Writes the execution value to the current field. During deployment, this indicates that the field should be stored as an index field.
summary Writes the execution value to the current field. During deployment, this indicates that the field should be included in the document summary.

Arithmetics

Indexing statements can contain any combination of arithmetic operations, as long as the operands are numeric values. In case you need to convert from string to numeric, or convert from one numeric type to another, use the applicable converter expression. The supported arithmetic operators are:

Operator Description
<lhs> + <rhs> Sets the execution value to the result of adding of the execution value of the lhs expression with that of the rhs expression.
<lhs> - <rhs> Sets the execution value to the result of subtracting of the execution value of the lhs expression with that of the rhs expression.
<lhs> * <rhs> Sets the execution value to the result of multiplying of the execution value of the lhs expression with that of the rhs expression.
<lhs> / <rhs> Sets the execution value to the result of dividing of the execution value of the lhs expression with that of the rhs expression.
<lhs> % <rhs> Sets the execution value to the remainder of dividing the execution value of the lhs expression with that of the rhs expression.
<lhs> . <rhs> Sets the execution value to the concatenation of the execution value of the lhs expression with that of the rhs expression. If both lhs and rhs are collection types, this operator will append rhs to lhs (if any operand is null, it is treated as an empty collection). If not, this operator concatenates the string representations of lhs and rhs (if any operand is null, the result is null).

You may use parenthesis to declare precedence of execution (e.g. (1 + 2) * 3). This also works for more advanced array concatenation statements such as (input str_a | split ',') . (input str_b | split ',') | index arr.

Converters

These expressions let you convert from one data type to another.

Converter Input Output Description
binarize [threshold] Any tensor Any tensor

Replaces all values in a tensor by 0 or 1. This takes an optional argument specifying the threshold a value needs to be larger than to be replaced by 1 instead of 0. The default threshold is 0. This is useful to create a suitable input to pack_bits.

embed [id] String A tensor

Invokes an embedder to convert a text to one or more vector embeddings. The type of the output tensor is what is required by the following expression (as supported by the specific embedder). Arguments are given space separated, as in embed colbert chunk. The first argument is the id of the embedder, and can be omitted when only one is configured. Any additional arguments are passed to the embedder implementation.
hash String int or long

Converts the input to a hash value (using SipHash). The hash will be int or long depending on the target field.
pack_bits A tensor A tensor

Packs the values of a binary tensor into bytes with 1 bit per value in big-endian order.

The input tensor must:

  • Only have values that are 0 or 1
  • Have a single dense dimension

It can have any value type and any number of sparse dimensions.

The output tensor will have:

  • int8 as the value type.
  • The dense dimension size divided by 8 (rounded upwards to integer).
  • The same sparse dimensions as before.

The resulting tensor can be unpacked during ranking using unpack_bits. A tensor can be converted to binary form suitable as input to this by the binarize function.

to_array Any Array<inputType>

Converts the execution value to a single-element array.
to_byte Any Byte

Converts the execution value to a byte. This will throw a NumberFormatException if the string representation of the execution value does not contain a parseable number.
to_double Any Double

Converts the execution value to a double. This will throw a NumberFormatException if the string representation of the execution value does not contain a parseable number.

to_float Any Float

Converts the execution value to a float. This will throw a NumberFormatException if the string representation of the execution value does not contain a parseable number.
to_int Any Integer

Converts the execution value to an int. This will throw a NumberFormatException if the string representation of the execution value does not contain a parseable number.
to_long Any Long

Converts the execution value to a long. This will throw a NumberFormatException if the string representation of the execution value does not contain a parseable number.
to_bool Any Bool

Converts the execution value to a boolean type. If the input is a string it will become true if it is not empty. If the input is a number it will become true if it is != 0.
to_pos String Position

Converts the execution value to a position struct. The input format must be either a) [N|S]<val>;[E|W]<val>, or b) x;y.
to_string Any String

Converts the execution value to a string.
to_uri String Uri

Converts the execution value to a URI struct
to_wset Any WeightedSet<inputType>

Converts the execution value to a single-element weighted set with default weight.
to_epoch_second String Long

Converts an ISO-8601 instant formatted String to Unix epoch (or Unix time or POSIX time or Unix timestamp) which is the number of seconds elapsed since January 1, 1970, UTC. The converter uses java.time.Instant.parse to parse the input string value. This will throw a DateTimeParseException if the input cannot be parsed. Examples:

  • 2023-12-24T17:00:43.000Z is converted to 1703437243L
  • 2023-12-24T17:00:43Z is converted to 1703437243L
  • 2023-12-24T17:00:43.431Z is converted to 1703437243L
  • 2023-12-24T17:00:43.431+00:00 is converted to 1703437243L

Other expressions

The following are the unclassified expressions available:

ExpressionDescription
_

Returns the current execution value. This is useful, e.g., to prepend some other value to the current execution value, see this example.

attribute <fieldName>

Writes the execution value to the named attribute field.
base64decode

If the execution value is a string, it is base-64 decoded to a long integer. If it is not a string, the execution value is set to Long.MIN_VALUE.

base64encode

If the execution value is a long integer, it is base-64 encoded to a string. If it is not a long integer, the execution value is set to null.

echo

Prints the execution value to standard output, for debug purposes.
flatten

for_each { <script> }

Executes the given indexing script for each element in the execution value. Here, element refers to each element in a collection, or each field value in a struct.

get_field <fieldName>

Retrieves the value of the named field from the execution value (which needs to be either a document or a struct), and sets it as the new execution value.

get_var <varName>

Retrieves the value of the named variable from the execution context and sets it as the execution value. Note that variables are scoped to the indexing script of the current field.

hex_decode

If the execution value is a string, it is parsed as a long integer in base-16. If it is not a string, the execution value is set to Long.MIN_VALUE.

hex_encode

If the execution value is a long integer, it is converted to a string representation of an unsigned integer in base-16. If it is not a long integer, the execution value is set to null.

hostname

Sets the execution value to the name of the host computer.
if (<left> <cmp> <right>) {
    <trueScript>
}
[ else { <falseScript> } ]

Executes the trueScript if the conditional evaluates to true, or the falseScript if it evaluates to false. If either left or right is null, no expression is executed. The value produced is the value returned from the chosen branch, and these must produce values of compatible types (or none).

index <fieldName>

Writes the execution value to the named index field.
input <fieldName>

Retrieves the value of the named field from the document and sets it as the execution value. The field name may contain '.' characters to retrieve nested struct fields.

join "<delim>"

Creates a single string by concatenating the string representation of each array element of the execution value. This function is useful or indexing data from a multivalue field into a singlevalue field.

lowercase

Lowercases all the strings in the execution value.
ngram <size>

Adds ngram annotations to all strings in the execution value.
normalize

normalize the input data. The corresponding query command for this function is normalize.

now

Outputs the current system clock time as a UNIX timestamp, i.e. seconds since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time (Epoch).

random [ <max> ]

Returns a random integer value. Lowest value is 0 and the highest value is determined either by the argument or, if no argument is given, the execution value.

sub-expression1 || sub-expression2 || ...

Returns the value of the first alternative sub-expression which returns a non-null value. See this example.

select_input {
( case <fieldName>: <statement>; )*
}

Performs the statement that corresponds to the first named field that is not empty (see example).

set_language

Sets the language of this document to the string representation of the execution value. Parses the input value as an RFC 3066 language tag, and sets that language for the current document. This affects the behavior of the tokenizer. The recommended use is to have one field in the document containing the language code, and that field should be the first field in the document, as it will only affect the fields defined after it in the schema. Read linguistics for more information on how language settings are applied.

set_var <varName>

Writes the execution value to the named variable. Note that variables are scoped to the indexing script of the current field.

substring <from> <to>

Replaces all strings in the execution value by a substring of the respective value. The arguments are inclusive-from and exclusive-to. Both arguments are clamped during execution to avoid going out of bounds.

split <regex>

Splits the string representation of the execution value into a string array using the given regex pattern. This function is useful for creating multivalue fields such as an integer array out of a string of comma-separated numbers.

summary <fieldName>

Writes the execution value to the named summary field. Summary fields of type string are limited to 64 kB. If a larger string is stored, the indexer will issue a warning and truncate the value to 64 kB.

switch {
( case '<value>': <caseStatement>; )*
[ default: <defaultStatement>; ]
}

Performs the statement of the case whose value matches the string representation of the execution value (see example).

tokenize [ normalize ] [ stem ]

Adds linguistic annotations to all strings in the execution value. Read linguistics for more information.

trim

Removes leading and trailing whitespace from all strings in the execution value.
uri

Converts all strings in the execution value to a URI struct. If a string could not be converted, it is removed.