Other ranking properties

 

These properties affect how LIKEP and some LIKE queries are processed.

likeprows
Only the top likeprows relevant documents are returned by a LIKEP query (default 100). This is an arbitrary cut-off beyond which most results would be increasingly useless. It also speeds up the query process, because fewer rows need to be sorted during ranking. By altering likeprows this threshold can be changed, e.g. to return more results to the user (at the potential cost of more search time). Setting this to 0 will return all relevant documents (no limit).

Note that in some circumstances, a LIKEP query might return more than likeprows results, if for example later processing requires examination of all LIKEP-matching rows (e.g. certain AND queries). Thus a SQL statement containing LIKEP may or may not be limited to likeprows results, depending on other clauses, indexes, etc.

likepmode
Sets the mode for LIKEP queries. This can be either 0, for early, or 1 for late. The default is 1, which is the correct setting for almost all cases. Does not apply to most Metamorph index searches.

likepallmatch
Setting this to 1 forces LIKEP to only consider those documents containing all query terms as valid hits (i.e. just as LIKE does). By default, since LIKEP is a ranking operator it returns the best results even if only some of the set-logic terms (non-+ or - prefix) can be found. (Note that required terms - prefixed with a + - are always required in a hit regardless of this setting.)

likepobeyintersects
Setting this to 1 forces LIKEP to obey the intersects operator (@) in queries. By default LIKEP does not use it, because it is a ranking operator. Setting both likepallmatch and likepobeyintersects to 1 will make LIKEP respect queries the same as LIKE. (Note: apicp alintersects may have to be enabled in Vortex as well.)

likepinfthresh
This controls the "infinity" threshold in LIKE and LIKEP queries: if the estimated number of matching rows for a set is greater than this, the set is considered infinitely-occurring. If all the search terms found in a given document are such infinite sets, the document is given an estimated rank. This saves time ranking irrelevant but often-occurring matches, at the possible expense of rank position. The default is 0, which means infinite (no infinite sets; rank all documents).

likepindexthresh
Controls the maximum number of matching documents to examine (default infinite) for LIKEP and LIKE. After this many matches have been found, stop and return the results obtained so far, even if more hits exist. Typically this would be set to a high threshold (e.g. 100000): a query that returns more than that many hits is probably not specific enough to produce useful results, so save time and don't process the remaining hits. (It's also a good bet that something useful was already found in the initial results.) This helps keep such noisy queries from loading a server, by stopping processing on them early. A more specific query that returns fewer hits will fall under this threshold, so all matches will be considered for ranking.

Note that setting likepindexthresh is a tradeoff between speed and accuracy: the lower the setting, the faster queries can be processed, but the more queries may be dropping potentially high-ranking hits.


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