APPENDIX DDirect SGA Access
You may wonder why there is a need to access the SGA directly when friendly SQL and powerful trace facility are available. There are many benefits to accessing the SGA directly. Besides the ability to do high frequency sampling, it is possible to get processes’ statistics even when the database or instance is hung and new connections cannot be established. This typically happens in very big sites with large SGAs and user populations, and the problem is normally caused by bugs in either the operating system or database. When this situation arises, the only way to get diagnostic statistics from Oracle is by accessing the SGA directly using external programs.
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