Local buffers

A local buffer is a buffer that is used for input and output of data stored in RDAREAs on disk, and is allocated in process private memory. Table 6-10 lists and describes the types of local buffers available.

Table 6-10 Types of local buffers

Local buffer type	Description
Data local buffer	Local buffers used for table data I/O. Data local buffers are allocated on a per-RDAREA basis.
Index local buffer	Local buffers used for index data I/O. Index local buffers are allocated on a per-index basis.

You can use these local buffers to improve performance. For example, by separately defining data local buffers and index local buffers, data and index searches each operate independently, even if they are running at the same time. This enables the number of index I/O operations to be reduced even for a full text search of a large amount of data, resulting in reduced processing time. Figure 6-14 provides an overview of local buffers.

Figure 6-14 Overview of local buffers

[Figure]

Organization of this subsection: (1) Local buffer application criteria; (2) Local buffer allocation procedure

(1) Local buffer application criteria

Defining local buffers is beneficial if all of the following conditions are satisfied:

A large amount of data is being searched or updated.
The RDAREA to be accessed cannot be accessed from another UAP.

However, do not define local buffers for a UAP that establishes an emergency connection to HiRDB, due to the significant adverse effects it has on the system (memory resource strain, process monopolization, and so on.).

(2) Local buffer allocation procedure

Use the pdlbuffer operand to allocate local buffers. The following example shows how to use the pdlbuffer operand to allocate local buffers:

Example:

pdlbuffer -a localbuf01 -r RDAREA01,RDAREA02 -n 1000  . . .1
pdlbuffer -a localbuf02 -i USER01.INDX01 -n 1000  . . .2

Explanation

Allocates data local buffers to two RDAREAs (RDAREA01 and RDAREA02).
Allocates an index local buffer to an index (USER01.INDX01).

For details about the pdlbuffer operand, see the HiRDB Version 8 System Definition.

6.8.10 Local buffers

(1) Local buffer application criteria

(2) Local buffer allocation procedure