Limit -- describes a fast limit




Limit {name} {sql}

Limit describes an SQL query returning a list of URL IDs and associates the list with the given name. The query is executed during execution of indexer -Eblob, indexer -Erewriteurl or indexer -Erewritelimits and its results are stored in the database in a compact way which allows to fetch the limit during search time very efficiently.

Note: Use the fl search.cgi parameter to load a previously created fast limit at search time.

Note: Starting from the version 3.2.39, it's also possible to specify the fl parameter in the DBAddr command in search.htm, to set different limits for the databases listed in the template.

Fast limits work much faster than section limits which are activated by using the sl search parameter described in the Section called Search parameters in Chapter 11.

Unlike section limits, fast limits are suitable for huge databases and can use very complex WHERE conditions, typically on the url and urlinfo mnoGoSearch tables, but can also use joins with external tables.

Fast limits work only with the databases supporting DBMode=blob (see the Section called Storage mode - blob in Chapter 7) and reuse the bdict table in the mnoGoSearch database, however they are available for DBMode=single and DBMode=multi as well.

Note: If you use DBMode=single or DBMode=multi, then run indexer -Erewritelimits to create or update fast limits after indexing.

Note: If you use DBMode=blob then fast limits are recreated automatically during execution of indexer -Eblob or indexer -Erewriteurl, however you can still use indexer -Erewritelimits for quick rewrite of fast limits without touching other data.

Starting from the version 3.2.39, it is also possible to specify the Limit command directly in search.htm without having to cache the desired limits using indexer -Eblob. It can be useful for the limits whose SQL queries work very efficiently and return a very small number of documents.


Limit mod  "SELECT rec_id FROM url WHERE url LIKE '%/mod/%'"
Limit html "SELECT url_id FROM urlinfo WHERE sname='Content-Type' AND sval='text/html'"

See also

UserScore, the Section called Search parameters in Chapter 11, the Section called Storage mode - blob in Chapter 7, DBAddr.