Introduction to Informix 11.5 new features: part 1th

The latest version of the Informix database is 11.5, from Informix 9, Informix 10 to Informix 11.5, in terms of database performance, database management, and application development, and a number of very useful new features are being introduced. The use of these features can greatly improve the database performance, enhance the manageability of the database and the flexibility of application development. We are here to introduce some of these characteristics, I hope to be helpful to you.

Some practical features of database management

Use a configurable page size

We know that in Informix, the most basic unit of data storage is the page, before Informix version 10, the size of the data page is fixed and cannot be changed, usually on platforms such as Sun, HP, 2k,aix and Windows platforms, The size of the data page is 4K. Starting with the Informix 10 release, we can configure the size of the Informix database page, which can be a 2k-16k size. By providing configurable page size features, there are a number of benefits that can be brought to us:

The efficiency of space use will be higher

Starting with Informix 10, a page can achieve 16K of contiguous space and use data space more efficiently. For example, we have a row in the table data size of 1200 bytes, then, when using 2K size page, can only hold 1 rows of data, 3 rows of data need 6K size space, if the 4K size page, then 3 rows of data can be placed on a 4K page, space will save% 33. Then, when the 30 rows of data, if the 2K size of the page, you need to occupy 60k size space, if the 4K size page, only need to occupy 40k size space, if the 6k size page, you only need to occupy the 36k size space, you can save 40% of the space.

Supports larger index key values, up to 3K max.

In this way, we can place more index keys on one index page, and support larger key values without adding to the hierarchy of the index tree. With the configurable page size feature, you can significantly improve processing performance with a large number of duplicate index key values.

Increase in Access efficiency

By using the Configurable page size feature, you can reduce the number of IO operations on data pages and index pages and improve access efficiency. By configuring the page size, long record lines can be stored only on a single page, reducing the number of pages that read each record; In previous releases, long records required remainders pages, with large pages sufficient to hold the entire record, omitting access to the remainders pages of time; Large index pages can hold more index entries, which reduces the number of layers in the index, and reduces the overhead of traversing through the index tree; In a decision support application environment, using large pages can reduce the number of pages scanned by the entire table and improve operational efficiency.

We can define the size of the data page at the database space (Dbspace) level and at the buffer pool level, which can be 2k-16k, and the defined data page size must be a multiple of the system default page size. Configurable page size features require the system to turn on large chunks (large chunk) features.

This feature allows you to specify a standard or temporary dbspace page size when creating Dbspace. If you want to use a key that is longer than the key allowed by the default page size, you may need to specify a non-default page size. The root dbspace uses the default page size. If you want to specify a page size, the specified value must be an integer multiple of the default page size, and not more than KB.

The basic syntax for creating dbspace using the Onspaces command is as follows:

onspaces　–　c　–　d　dbs　–　k　pgsize　–　p　path　-o　offset　-s　size　；

Where pgsize is used to specify the page size of the Dbspace (in K):

The page size ranges from 2K to 16K.

The page size must be a multiple of the default page size (2k or 4K).

The page size cannot be modified after Dbspace is created.

If the corresponding page size buffer pool does not exist, online will automatically create one by configuring the parameter buffers_def.

Rootdbs must use the system default page size.

Dynamically created log files must be allocated on a database space that uses the default page size of the system.

When creating a buffer pool, we can use the new Bufferpool configuration parameter or the Onparams tool to define a buffer pool for all pages in the dbspace that are not of the default page size. When you define a buffer pool using the Bufferpool configuration parameter or the Onparams tool, you specify the buffer pool information, including size, number of LRUs in the buffer pool, number of buffers in the buffer pool, lru_min_dirty, and Lru_max_dirty values. Buffers, LRUs, Lru_max_dirty, and Lru_min_dirty configuration parameters are no longer used. In version 10.0, the information previously specified in the buffers, LRUs, Lru_max_dirty, and Lru_min_dirty configuration parameters is now specified using the Bufferpool configuration parameter or the Onparams tool. The information entered using the Bufferpool configuration parameter or the Onparams tool replaces the information previously specified with an outdated parameter.

The basic syntax for specifying a buffer pool through Onparams is as follows:

onparams　–　b　–　g　pgsize　–　n　buffs　–　r　lrus　–　x　max　–　m　min　；