blocks|key|5402241|text|问得好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5402242|除非您想将数组转换为一组规范化的表，否则您可能会考虑序列化。|5402243|序列化是一个奇特的词，用于将对象转换为可以保存到磁盘或数据库的某种格式。序列化的两种主要格式是二进制和XML，我敢打赌Java对此有一定的支持。|5402244|根据您使用的数据类型，您应该能够将数组转换为XML或二进制，然后将其保存到数据库中的单个字段中。您可以通过查看http://java.sun.com/developer/technicalArticles/Programming/serialization/来开始使用Java语言中的这项技术。我知道它内置于.NET中。|offset|length|5402245|希望这能有所帮助。如果我能给你更多的指导，请告诉我。|5402246|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/developer/technicalArticles/Programming/serialization/^0|0|0|0|1J|22|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@$H|X|I|Y|1|Z]]|A|$]]|$1|J|3|K|5|6|7|10|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]]]

Great question.

Unless you want to translate your arrays into a set of normalized tables, which it sounds like you don't, you might want to contemplate serialization.

Serialization is a fancy word for turning objects into some format that you can save to disk or a database. The two major formats for serialization are binary and XML, and I'm betting that Java has some support for it.

Depending on what data types you're using, you should be able to turn your array into XML or binary and then save that to a single field in the database. You could get started with this technique in Java by checking out <a href="http://java.sun.com/developer/technicalArticles/Programming/serialization/" rel="noreferrer">http://java.sun.com/developer/technicalArticles/Programming/serialization/</a>. I know that it's built into .NET.

Hope that this helps. Let me know if I can give you any more direction.

blocks|key|3146349|text|将数据存储为BLOB并使用Java将BLOB解码为实际的Java数组如何？一口气存储和检索整个数组的效率会高得多，但对单个元素的处理就很糟糕了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3146350|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

How about storing the data as a BLOB and using Java to decode the BLOB into an actual Java array? It would be much more efficient for storing and retrieving the whole array in one gulp, but would be terrible for twiddling individual elements.

blocks|key|830094|text|提出一种内部表示形式--可以是XML、JSON、您自己编写的某个二进制文件，也可以是任何其他形式的序列化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|830095|使用"blob“数据类型将其存储在表中。将与基准表关联的任何元数据存储在其他列中。|830096|我强烈反对这样的观点:创建一个行数和列数与矩阵相同的表--这是为不使用的功能付出的非常高的代价。|830097|事先准备好insert/select语句，并使用绑定变量更改正在处理的矩阵--不要让数据库重新解析每个请求。|830098|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Come up with an internal representation -- be it XML, JSON, some binary file you come up with yourself, or any other form of serialization.

Store it in a table using the "blob" datatype. Store any metadata associated with the matrix in additional columns.

I strongly disagree that the way to do it is to create a table with the same number of rows and columns as your matrix -- that is a very high price to pay for functionality you don't use.

Prepare your insert/select statements beforehand, and use bind variables to change what matrix you are working with -- don't make the db reparse every request.

blocks|key|3991539|text|如果它只有1个数组，为什么不使用二进制文件呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3991540|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

If its is only 1 array, why not use a binary file?

blocks|key|830157|text|正如前面所建议的:如果您不需要这些特性，就不要使用RDBMS。但是，您可能希望使用像JDBM这样的低级应用程序接口，它提供了一些数据库之类的特性，比如管理磁盘上的索引，而不是序列化。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|830158|entityMap|0|LINK|mutability|MUTABLE|url|http://jdbm.sourceforge.net/^0|16|4|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

As allready suggested: Don't use a RDBMS if you don't need the features. Instead of Serialization though you might want to concider a low level API like <a href="http://jdbm.sourceforge.net/" rel="nofollow noreferrer">JDBM</a> that provides some database like features like managing an on-disk index.

blocks|key|826042|text|如果您的数据是密集打包的(值直方图接近于扁平线)，那么您的最佳选择是使用ObjectOutput/InputStream的blob和序列化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|826043|否则，您可能会发现使用稀疏数组和实体-属性-值模式的变体更有效。下面是一个示例：|826044|+Name+%7C+IndexKey++%7C+Value
------%2B-----------%2B-------
+foo++%7C+'default'+%7C+39++++++++
+foo++%7C+0:0:0+++++%7C+23
+foo++%7C+0:0:1+++++%7C+34
+foo++%7C+1:5:0+++++%7C+12
+...
+bar++%7C+1:3:8+++++%7C+20
+bar++%7C+1:3:8+++++%7C+23
+bar++%7C+1:1:1+++++%7C+24
+bar++%7C+3:0:6+++++%7C+54
+...|code-block|syntax|javascript|826045|这还允许您快速更新表的某些部分，并使用SQL+'like‘操作符选择切片。|826046|如果您的维度数量是固定的，将键列分解为每个维度的int列，以提高索引效率并具有更灵活的选择条件(您可以对元数据使用第一个索引'null‘，如默认值)。|826047|在任何情况下，对Name、IndexKey列创建聚集索引都是一个好主意。|826048|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

If your data is densely packed (the values histogram is close to flat line), your best choice is blob and serialization using Object[Output/Input]Stream.

Otherwise, you might find it more efficient to use sparse arrays and variation of Entity-Attribute-Value schema. Here is an example:

<pre><code> Name | IndexKey | Value
------+-----------+-------
 foo | 'default' | 39 
 foo | 0:0:0 | 23
 foo | 0:0:1 | 34
 foo | 1:5:0 | 12
 ...
 bar | 1:3:8 | 20
 bar | 1:3:8 | 23
 bar | 1:1:1 | 24
 bar | 3:0:6 | 54
 ...
</code></pre>

This also allows you fast updates to parts of the table and selecting slices using SQL 'like' operator. 

If the number of your dimensions is fixed to break down the key column to separate int columns for each dimension in order to improve the index efficiency and have more flexible selection criteria (you can use first index 'null' for metadata like the default value). 

In any case, it is a good idea to create a clustered index on Name,IndexKey columns.

blocks|key|5402097|text|使用数组保存的数据定义一个表，并将数组值插入到表中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5402098|这是非常简单的数据访问/存储。你的数组维数总是一样的吗？|5402099|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Define a table with the data your array holds and insert the array values into a table.

This is very simple data access/storage. Will your array dimensions always be the same?

blocks|key|825836|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|825837|在一个大型的显式事务中做到了这一点。不要强制数据库系统为每个insert创建新的隐式事务。|unordered-list-item|825838|使用预准备语句。|825839|825840|entityMap^0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|I|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|J|7|@]|8|@]|9|$]]|$1|D|3|E|4|C|6|K|7|@]|8|@]|9|$]]|$1|F|3|-4|4|5|6|L|7|@]|8|@]|9|$]]|$1|G|3|-4|4|5|6|M|7|@]|8|@]|9|$]]]|H|$]]

<ul>
<li>Do it in one big explicit transaction. Don't force the database system to create a new implicit transaction for every insert.</li>
<li>Use a prepared statement.</li>
</ul>

blocks|key|825914|text|PostgreSQL内置了对数组的支持。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|825915|http://www.postgresql.org/docs/8.0/interactive/arrays.html|offset|length|825916|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1M|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@$D|O|E|P|1|Q]]|A|$]]|$1|F|3|-4|5|6|7|R|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|C]]]]

PostgreSQL has built-in support for arrays.

<a href="http://www.postgresql.org/docs/8.0/interactive/arrays.html" rel="nofollow noreferrer">http://www.postgresql.org/docs/8.0/interactive/arrays.html</a>

blocks|key|830229|text|Java序列化到存储为BLOB的字节数组将是您最好的选择。Java将非常高效地序列化大型数组。对于任何您感兴趣的查询或容易显示的内容，请使用其余的行列。如果您经常查询和报告非BLOB数据，最好将BLOB保存在它们自己的表中，并让“常规”行指向"BLOB“行(尽管这可能因数据库实现而异)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|830230|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Java Serialization to a Byte Array stored as a BLOB will be your best bet. Java will serialized a large array quite efficiently. Use the rest of the rows columns for anything you're interested in querying upon or displaying readily. It can also be a good idea to keep the BLOBs in their own table and have the "regular" rows point to the "BLOB" rows, if you query and report on the non-BLOB data much (though this can vary by database implementation).

blocks|key|5402611|text|HSQLDB+2.0支持将一维数组存储为表的一列。因此，表的每一行将对应于二维数组的一行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5402612|但是，如果你想作为一个整体检索一个2D数组，BLOB是最好的解决方案。|5402613|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

HSQLDB 2.0 supports one dimensional arrays stored as a column of the table. So each row of the table will correspond to one row of the 2D array.

But if you want to retreive a 2D array as a whole, BLOB is the best solution.

What is the most efficient way to store large arrays (10000x100) in a database, say, hsqldb? I need to do this for a certain math program that I'm writing in java. Please help.
The whole array will be retrieved and stored often (not so much individual elements). Also, some meta-data about the array needs to be stored about the array.

Storing arrays in databases

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在数据库(比如hsqldb )中存储大型数组(10000x100)的最有效方法是什么？我需要为我用java编写的某个数学程序这样做。请帮帮忙。整个数组将经常被检索和存储(不是那么多单独的元素)。此外，还需要存储有关该数组的一些元数据。

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