indexing

问题 I would like to use a GIN index on uuid[] (to have efficient membership tests for arrays of uuids). However when I try it PostgreSQL gives me an error: mydb=> CREATE TABLE foo (val uuid[]); CREATE TABLE mydb=> CREATE INDEX foo_idx ON foo USING GIN(val); ERROR: data type uuid[] has no default operator class for access method "gin" HINT: You must specify an operator class for the index or define a default operator class for the data type. How can I add the necessary operator class so that it

问题 I'd like to specify an analyzer, name it, and use that name in a mapping while creating an index. I'm lost, my ES instance always returns me an error message. This is, roughly, what I'd like to do: "settings": { "mappings": { "alfedoc": { "properties": { "id": { "type": "string" }, "alfefield": { "type": "string", "analyzer": "alfeanalyzer" } } } }, "analysis": { "analyzer": { "alfeanalyzer": { "type": "pattern", "pattern":"\\s+" } } } } But this does not seem to work; the ES instance always

问题 How do you drop an index only if it exists? It seems simple but I did found anything on the net. The idea is to drop it only if it exists, because if not, I will have an error and my process stops. I found this to find if the index exists: select index_name from user_indexes where table_name = 'myTable' and index_name='myIndexName' But I don't know how to put it together with DROP INDEX myIndexName 回答1: DECLARE COUNT_INDEXES INTEGER; BEGIN SELECT COUNT ( * ) INTO COUNT_INDEXES FROM USER

问题 I am newbie in Lucene, and I'm having some problems creating simple code to query a text file collection . I tried this example, but is incompatible with the new version of Lucene. UDPATE: This is my new code, but it still doesn't work yet. 回答1: Lucene is a quite big topic with a lot of classes and methods to cover, and you normally cannot use it without understanding at least some basic concepts. If you need a quickly available service, use Solr instead. If you need full control of Lucene,

问题 I have something like this... $( 'ul li' ).each( function( index ) { $( this ).append( ',' ); } ); I need to know what index will be for last element, so I can do like this... if ( index !== lastIndex ) { $( this ).append( ',' ); } else { $( this ).append( ';' ); } Any ideas, guys? 回答1: var total = $('ul li').length; $('ul li').each(function(index) { if (index === total - 1) { // this is the last one } }); 回答2: var arr = $('.someClass'); arr.each(function(index, item) { var is_last_item =

问题 What's the real difference between a caching solution and an indexing solution? It seems to me that an indexing solution is in fact caching with the ability to run search queries (like: Elastic Search). Would there ever be any real reason to use both a caching solution and indexing solution within the same project or does the indexing solution basically make any other caching redundant? Example: Say I use NEST for ElasticSearch, which would store and return POCOs; if I then query

问题 I am using Eclipse PDT Helios with Aptana Studio on Windows XP SP3. Very often, my workflow is interrupted because Eclipse starts a DLTK indexing process that lasts 30 seconds, sometimes up to 2 minutes - which is annoying. I wonder if there is any way to: Either turn that off or Run the DLTK indexing process less frequently. I didn't find any possibility to change regarding parameters in Window > Preferences. 回答1: PDT 2.2 (the one in Helios) is using a local database engine, H2, to store

问题 What are the R equivalents for these Python list comprehensions: [(i,j) for i,j in zip(index, Values)] [(i,j) for i,j in enumerate(Values)] [(i,j) for i,j in enumerate(range(10,20))] %MWE, indexing or enumerating to %keep up with the index, there may %be some parameter to look this up Example with Output >>> [(i,j) for i,j in enumerate(range(10,20))] [(0, 10), (1, 11), (2, 12), (3, 13), (4, 14), (5, 15), (6, 16), (7, 17), (8, 18), (9, 19)] I have solved this problem earlier with some trick in

问题 I have three tables in my app, call them tableA , tableB , and tableC . tableA has fields for tableB_id and tableC_id , with indexes on both. tableB has a field foo with an index, and tableC has a field bar with an index. When I do the following query: select * from tableA left outer join tableB on tableB.id = tableA.tableB_id where lower(tableB.foo) = lower(my_input) it is really slow (~1 second). When I do the following query: select * from tableA left outer join tableC on tableC.id =

问题 I have a single table with four columns... `id` INT(11) NOT NULL AUTO_INCREMENT `tid` INT(11) NOT NULL `cid` INT(11) NOT NULL `name` NVARCHAR(4096) NULL DEFAULT NULL id is the unique primary key. The other columns are not unique. I want to return the list of all id values that have specific tid and cid values and are sorted by the name. So this... select id from myTable where cid = 1 && tid = 1 order by name There are about 125k records in the table and there should be around 50k that happen