autodiacsens
auto-trigger diacritics sensitivity (raw index only). IF the index is not stripped, decide if we automatically trigger diacritics sensitivity if the search term has accented characters (not in unac_except_trans). Else you need to use the query language and the "D" modifier to specify diacritics sensitivity. Default is no.
autocasesens
auto-trigger case sensitivity (raw index only). IF the index is not stripped (see indexStripChars), decide if we automatically trigger character case sensitivity if the search term has upper-case characters in any but the first position. Else you need to use the query language and the "C" modifier to specify character-case sensitivity. Default is yes.
maxTermExpand
Maximum query expansion count for a single term (e.g.: when using wildcards). This only affects queries, not indexing. We used to not limit this at all (except for filenames where the limit was too low at 1000), but it is unreasonable with a big index. Default 10000.
maxXapianClauses
Maximum number of clauses we add to a single Xapian query. This only affects queries, not indexing. In some cases, the result of term expansion can be multiplicative, and we want to avoid eating all the memory. Default 50000.
snippetMaxPosWalk
Maximum number of positions we walk while populating a snippet for the result list. The default of 1,000,000 may be insufficient for very big documents, the consequence would be snippets with possibly meaning-altering missing words.
thumbnailercmd
Command to use for generating thumbnails. If set, this should be a path to a command or script followed by its constant arguments. Four arguments will be appended before execution: the document URL, MIME type, target icon SIZE (e.g. 128), and output file PATH. The command should generate a thumbnail from these values. E.g. if the MIME is video, a script could use: ffmpegthumbnailer -iURL -oPATH -sSIZE.