Big buffers

A big buffer is a single buffer that is made up of several pages. The actual number of pages is platform-dependent.

The database server allocates big buffers to improve performance on large reads and writes. The database server uses a big buffer whenever it writes to disk multiple pages that are physically contiguous. For example, the database server tries to use a big buffer to perform a series of sequential reads (light scans) or to read into shared memory simple large objects that are stored in a dbspace.

Users do not have control over the big buffers. If the database server uses light scans, it allocates big buffers from shared memory.

For information about monitoring big buffers with the onstat command, see the topics about configuration effects on I/O activity in your HCL Informix® Performance Guide.

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