download barcode font for Optimizing mass indexing in Java

Paint DataMatrix in Java Optimizing mass indexing

Optimizing mass indexing
Data Matrix 2d Barcode Generation In Java
Using Barcode drawer for Java Control to generate, create Data Matrix image in Java applications.
ECC200 Recognizer In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Reindexing your entire data set or a significant part of your data set can be a long process if you do it the wrong way. This section will help you to make it as efficient as possible. Indexing a huge data set involves two distinct but interwoven operations: You need to read objects from the database, and then you need to index them. Most of the performance problems arise on the first operation. Hibernate Search needs to have access to the object and all its associated indexed objects during the indexing operation. The object, its @IndexedEmbedded associations, and its @ContainedIn associations (recursively) form the object graph used during indexing. Use the following techniques to load this graph as efficiently as possible:
QR Code 2d Barcode Creation In Java
Using Barcode encoder for Java Control to generate, create QR image in Java applications.
Print QR Code ISO/IEC18004 In Java
Using Barcode maker for Java Control to generate, create QR Code JIS X 0510 image in Java applications.
Write the appropriate query using joins. Use @BatchSize or FetchMode.SUBSELECT when a direct join cannot be used. Load lazy properties if they are indexed (for example, use the fetch all properties syntax in HQL).
UPC-A Generation In Java
Using Barcode creator for Java Control to generate, create UPC Symbol image in Java applications.
Drawing Linear Barcode In Java
Using Barcode encoder for Java Control to generate, create Linear 1D Barcode image in Java applications.
If you don t pay attention, Hibernate Search might trigger some n+1 load problems while indexing your data. Listing 9.2 is an example of the query needed to load Item objects provided that their Distributor association is marked as @IndexedEmbedded.
Encode PDF417 In Java
Using Barcode generation for Java Control to generate, create PDF 417 image in Java applications.
Painting ISBN In Java
Using Barcode printer for Java Control to generate, create Bookland EAN image in Java applications.
Listing 9.2 When indexing objects, load using a query to minimize n+1 problems
Data Matrix 2d Barcode Generation In Java
Using Barcode printer for Android Control to generate, create DataMatrix image in Android applications.
Data Matrix Creator In Java
Using Barcode creation for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
Criteria query = session.createCriteria( Item.class ) .setFetchMode( "distributor", FetchMode.JOIN ) .setResultTransformer( CriteriaSpecification.DISTINCT_ROOT_ENTITY );
Generating Denso QR Bar Code In .NET
Using Barcode generator for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Barcode Generator In Visual C#.NET
Using Barcode drawer for .NET framework Control to generate, create Barcode image in VS .NET applications.
B Load necessary associations C
Make Denso QR Bar Code In Java
Using Barcode drawer for Android Control to generate, create QR Code JIS X 0510 image in Android applications.
Create Code 39 In VS .NET
Using Barcode printer for Reporting Service Control to generate, create Code-39 image in Reporting Service applications.
Distinct them (collection load)
Draw UPCA In Java
Using Barcode generation for BIRT reports Control to generate, create UPC-A image in BIRT reports applications.
Code 128C Creator In Visual C#
Using Barcode creation for VS .NET Control to generate, create ANSI/AIM Code 128 image in .NET framework applications.
Performance considerations
Scan ANSI/AIM Code 39 In C#
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
Make UPC Symbol In Visual Studio .NET
Using Barcode creation for VS .NET Control to generate, create UPC A image in VS .NET applications.
You need to fetch associations involved in the indexing process for this entity by using FetchMode B (you can also use static mappings such as @BatchSize). If you load collections, make sure you distinct the results to avoid indexing the same object multiple times C. (SQL loads the data for your main object for each element in your collection.)
Encoding GS1 - 12 In None
Using Barcode drawer for Font Control to generate, create UCC - 12 image in Font applications.
ANSI/AIM Code 39 Maker In None
Using Barcode generator for Excel Control to generate, create USS Code 39 image in Office Excel applications.
How to make sure all necessary data is fetched
Several strategies are available to make sure you haven t missed an association. The first one is to enable Hibernate Core logging and check queries going through. An n+1 pattern is readily recognizable; after a given query, you ll see a second query executed many, many times. The second approach is to use the Hibernate Core statistics API (available in SessionFactory.getStatistics()). When an entity is loaded under the cover, Hibernate increases getEntityFetchCount(). Be sure to enable statistics before testing by using statistics.setStatisticsEnabled(true).
The second most common problem occurs because your indexed data set cannot fit all data in memory (usually). If you attempt to load all objects, then index them, you ll likely face an OutOfMemoryException before you even finish loading objects. Make sure you use a scrollable result set and flush your index work queue and clear the session on a regular basis. This will limit the number of objects loaded into memory at a given time. Listing 9.3 demonstrates a typical mass indexing routine.
Listing 9.3 Mass indexing routine limiting objects loaded into memory
private static final int BATCH_SIZE = 1000; private static final int FETCH_SIZE = 100; public void indexAllItems() {
Run in a transaction
FullTextSession session = SessionHolder.getFullTextSession(); Criteria query = session.createCriteria( Item.class ) .setFetchMode("distributor", FetchMode.JOIN) .setResultTransformer( Minimize cache CriteriaSpecification.DISTINCT_ROOT_ENTITY) interaction .setCacheMode(CacheMode.IGNORE) .setFetchSize(FETCH_SIZE) Align batch .setFlushMode(FlushMode.MANUAL); size and JDBC
flush ScrollableResults scroll = query.scroll( ScrollMode.FORWARD_ONLY); Scroll in forward mode only int batch = 0; scroll.beforeFirst(); while ( ) { batch++; session.index( scroll.get(0) ); if (batch % BATCH_SIZE == 0) {
C fetch size
Optimizing indexing
//no need to session.flush() //we don't change anything session.flushToIndexes(); session.clear(); } } //the remaining non flushed index work //processed at commit time }
E Flush indexclear works and
the session
B It is a good practice to ignore the cache when dealing with a huge amount of data. The benefit doesn t overcome the cost of maintaining cache coherence. C Align JDBC
fetch size with the batch window size so that FETCH_SIZE = BATCH_SIZE/n to minimize memory consumption and database round trips. D Scrolling in forward mode loads objects on demand and makes sure objects (and their JDBC row representation) are garbage collectable. E After every BATCH_SIZE operations, flush changes to the indexes (flushToIndexes()) and free objects from the session (clear()). This will limit memory consumption. Be sure to run the indexing process in a transaction. If you don t, Hibernate Search needs to apply index changes when fullTextSession.index() is called, leading to expensive Lucene index opening and closing for each Item.
Copyright © . All rights reserved.