# Index scripts

The basic format is one or more field names followed by a colon, followed by one or more actions. Some actions take an optional or required parameter. The actions are applied in the specified order to each field listed, and fields can be listed in several lines.

Here's an example:

    desc1 : unhtml index truncate=200 field=sample
    desc2 desc3 desc4 : unhtml index
    name : field=caption weight=3 index
    ref : field=ref boolean=Q unique=Q
    type : field=type boolean=XT

The actions are:

boolean[=PREFIX]
  index the text as a single boolean term (with prefix PREFIX). If there's no text, no term is added. Omega expects certain prefixes to be used for certain purposes - those starting "X" are reserved for user applications. Q is reserved for a unique ID term.
date=FORMAT
  generate terms for date range searching. If FORMAT is "unix", then the value is interpreted as a Unix time_t (seconds since 1970). If FORMAT is "yyyymmdd", then the value is interpreted as an 8 digit string, e.g. 20021221 for 21st December 2002. Unknown formats, and invalid values are ignored at present.
field[=FIELDNAME]
  add as a field to the Xapian record. FIELDNAME defaults to the field name in the dumpfile. It is valid to have more than one instance of a given field: all instances will be processed and stored in the Xapian record.
hash[=LENGTH]
  Xapian has a limit on the length of a term. To handle arbitrarily long URLs as terms, omindex implements a scheme where the end of a long URL is hashed (short URLs are left as-is). You can use this same scheme in scriptindex. LENGTH defaults to 239, which if you index with prefix "U" produces url terms compatible with omindex.
index[=PREFIX]
  split text into words and index probabilistically (with prefix PREFIX if specified).
indexnopos[=PREFIX]
  split text into words and index probabilistically (with prefix PREFIX if specified), but don't include positional information in the database - this makes the database smaller, but phrase searching won't work.
load
  reads the contents of the file using the current text as the filename and then sets the current text to the contents. If the file can't be loaded (not found, wrong permissions, etc) then a diagnostic message is sent to stderr and the current text is set to empty. If the next action is truncate, then scriptindex is smart enough to know it only needs to load the start of a large file.
lower
  lowercase the text (useful for generating boolean terms)
spell
  Generate spelling correction data for any `index` or `indexnopos` actions in the remainder of this list of actions.
truncate=LENGTH
  truncate to at most LENGTH bytes, but avoid chopping off a word (useful for sample and title fields)
unhtml
  strip out HTML tags
unique[=PREFIX]
  use the value in this field for a unique ID. If the value is empty, a warning is issued but nothing else is done. Only one record with each value of the ID may be present in the index: adding a new record with an ID which is already present will cause the old record to be replaced (or deleted if the new record is otherwise empty). You should also index the field as a boolean field using the same prefix so that the old record can be found. In Omega, Q is reserved for use as the prefix of a unique term.
value=VALUESLOT
  add as a Xapian document value in slot VALUESLOT. Values can be used for collapsing equivalent documents, sorting the MSet, etc. If you want to perform numeric sorting, use the valuenumeric action instead.
valuenumeric=VALUESLOT
  Like value=VALUESLOT, this adds as a Xapian document value in slot VALUESLOT, but it encodes it for numeric sorting using Xapian::sortable_serialise(). Values set with this action can be used for numeric sorting of the MSet.
weight=FACTOR
  set the weighting factor to FACTOR (an integer) for any `index` or `indexnopos` actions in the remainder of this list of actions. The default is 1. Use this to add extra weight to titles, keyword fields, etc, so that words in them are regarded as more important by searches.

# Input files:

The data to be indexed is read in from one or more files. Each file has records separated by a blank line. Each record contains one or more fields of the form "name=value". If value contains newlines, these must be escaped by inserting an equals sign ('=') after each newline. Here's an example record:

    id=ghq147
    title=Sample Record
    value=This is a multi-line
    =value.  Note how each newline
    =is escaped.
    format=HTML

# Example:

See mbox2omega and mbox2omega.script for an example of how you can generate a dump file from an external source and write an index script to be used with it. Try "mbox2omega --help" for more information.