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Component/s
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contrib/*
[ 12312028
]
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Component/s
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Index
[ 12310232
]
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Fix Version/s
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2.9
[ 12312682
]
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Priority
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Major
[ 3
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Minor
[ 4
]
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Description
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Provides realtime search using Lucene. Conceptually, updates are divided into discrete transactions. The transaction is recorded to a transaction log which is similar to the mysql bin log. Deletes from the transaction are made to the existing indexes. Document additions are made to an in memory InstantiatedIndex. The transaction is then complete. After each transaction TransactionSystem.getSearcher() may be called which allows searching over the index including the latest transaction.
TransactionSystem is the main class. Methods similar to IndexWriter are provided for updating. getSearcher returns a Searcher class.
- getSearcher()
- addDocument(Document document)
- addDocument(Document document, Analyzer analyzer)
- updateDocument(Term term, Document document)
- updateDocument(Term term, Document document, Analyzer analyzer)
- deleteDocument(Term term)
- deleteDocument(Query query)
- commitTransaction(List<Document> documents, Analyzer analyzer, List<Term> deleteByTerms, List<Query> deleteByQueries)
Sample code:
{code}
// setup
FSDirectoryMap directoryMap = new FSDirectoryMap(new File("/testocean"), "log");
LogDirectory logDirectory = directoryMap.getLogDirectory();
TransactionLog transactionLog = new TransactionLog(logDirectory);
TransactionSystem system = new TransactionSystem(transactionLog, new SimpleAnalyzer(), directoryMap);
// transaction
Document d = new Document();
d.add(new Field("contents", "hello world", Field.Store.YES, Field.Index.TOKENIZED));
system.addDocument(d);
// search
OceanSearcher searcher = system.getSearcher();
ScoreDoc[] hits = searcher.search(query, null, 1000).scoreDocs;
System.out.println(hits.length + " total results");
for (int i = 0; i < hits.length && i < 10; i++) {
Document d = searcher.doc(hits[i].doc);
System.out.println(i + " " + hits[i].score+ " " + d.get("contents");
}
{code}
There is a test class org.apache.lucene.ocean.TestSearch that was used for basic testing.
A sample disk directory structure is as follows:
|/snapshot_105_00.xml | XML file containing which indexes and their generation numbers correspond to a snapshot. Each transaction creates a new snapshot file. In this file the 105 is the snapshotid, also known as the transactionid. The 00 is the minor version of the snapshot corresponding to a merge. A merge is a minor snapshot version because the data does not change, only the underlying structure of the index|
|/3 | Directory containing an on disk Lucene index|
|/log | Directory containing log files|
|/log/log00000001.bin | Log file. As new log files are created the suffix number is incremented|
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Realtime search with transactional semantics.
Possible future directions:
* Optimistic concurrency
* Replication
Encoding each transaction into a set of bytes by writing to a RAMDirectory enables replication. It is difficult to replicate using other methods because while the document may easily be serialized, the analyzer cannot.
I think this issue can hold realtime benchmarks which include indexing and searching concurrently.
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Affects Version/s
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2.4.1
[ 12313516
]
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Summary
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Ocean Realtime Search
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Realtime Search
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New Feature
Open
Minor
Near Realtime Search (using a built in RAMDirectory)
