In Oracle databases, many parameters are designed to be hidden from users to ensure that they don’t accidentally modify critical settings. These hidden parameters control various internal database features, optimizations, and behaviors that are not intended for routine administration. However, if you need to inspect or troubleshoot these parameters, Oracle provides a way to view and interact with them using specific SQL queries.<\/p>\n\n\n\n
In this blog post, we’ll explore how to check hidden database parameters in Oracle, including how to view all hidden parameters and how to view a specific hidden parameter.<\/p>\n\n\n\n
Hidden parameters in Oracle are prefixed with an underscore ( Here\u2019s a SQL query you can use to view all hidden parameters:<\/p>\n\n\n\n Explanation:<\/strong><\/p>\n\n\n\n If you are looking for the value of a specific hidden parameter, you can modify the query to filter by the name of that parameter. For instance, if you’re interested in the hidden parameter _mv_refresh_shrink_log<\/strong>, you can use the following query:<\/p>\n\n\n\n By running this query, you can find out the current value of the specific hidden parameter _mv_refresh_shrink_log<\/strong>.<\/p>\n\n\n\n Hidden parameters often control advanced features or internal workings of the database. They are not typically exposed to users because they can have a significant impact on the performance or stability of the system if altered. However, in certain situations, such as debugging performance issues, troubleshooting internal processes, or tuning database features, you might need to examine these hidden parameters.<\/p>\n\n\n\n While Oracle allows access to these hidden parameters for inspection, modifying them directly can be risky. Hidden parameters are not documented and can change between versions, so modifying them without understanding their purpose could lead to unexpected behavior or database instability.<\/p>\n\n\n\n If you need to change a hidden parameter, it’s highly recommended that you:<\/p>\n\n\n\n Checking hidden database parameters in Oracle is a powerful way to understand the internal workings of the database and troubleshoot advanced issues. By querying the Use the queries provided above to view hidden parameters and inspect their values as needed. If you\u2019re not sure about a particular hidden parameter, it\u2019s always a good idea to consult with Oracle Support or review the official Oracle documentation before making any change<\/p>\n","protected":false},"excerpt":{"rendered":" In Oracle databases, many parameters are designed to be hidden from users to ensure that they don’t accidentally modify critical settings. These hidden parameters control various internal database features, optimizations, and behaviors that are not intended for routine administration. However, if you need to inspect or troubleshoot these parameters, Oracle provides a way to view […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"googlesitekit_rrm_CAowu461DA:productID":"","footnotes":""},"categories":[1225],"tags":[],"class_list":["post-958","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/958","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/comments?post=958"}],"version-history":[{"count":1,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/958\/revisions"}],"predecessor-version":[{"id":959,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/958\/revisions\/959"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=958"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=958"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/tags?post=958"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}_<\/code>). To view all hidden parameters, you can query the internal x$ksppi<\/code> and x$ksppsv<\/code> tables. These tables store parameter names and values respectively, and are not normally accessible through the standard V$PARAMETER<\/code> or DBA_PARAMETERS<\/code> views.<\/p>\n\n\n\nSET PAGESIZE 50;\nSET LINESIZE 150;\nCOL ksppinm FORMAT A40 HEADING 'Parameter Name' JUSTIFY CENTER;\nCOL ksppstvl FORMAT A50 HEADING 'Parameter Value' JUSTIFY CENTER;\n\nSELECT \n ksppinm, ksppstvl \nFROM \n x$ksppi a, \n x$ksppsv b \nWHERE \n a.indx = b.indx \n AND substr(ksppinm, 1, 1) = '_';<\/code><\/pre>\n\n\n\n\n
2. View a Specific Hidden Parameter<\/strong><\/h3>\n\n\n\n
SET PAGESIZE 50;\nSET LINESIZE 150;\nCOL ksppinm FORMAT A40 HEADING 'Parameter Name' JUSTIFY CENTER;\nCOL ksppstvl FORMAT A50 HEADING 'Parameter Value' JUSTIFY CENTER;\n\nSELECT \n ksppinm, \n ksppstvl \nFROM \n x$ksppi a, \n x$ksppsv b \nWHERE \n a.indx = b.indx \n AND ksppinm = '_mv_refresh_shrink_log';<\/code><\/pre>\n\n\n\n\n
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3. Why Check Hidden Parameters?<\/strong><\/h3>\n\n\n\n
4. Caution While Modifying Hidden Parameters<\/strong><\/h3>\n\n\n\n
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Conclusion<\/h3>\n\n\n\n
x$ksppi<\/code> and x$ksppsv<\/code> tables, you can gain visibility into hidden parameters and their current values. However, always proceed with caution when considering modifying these parameters, as they can have a significant impact on the database\u2019s behavior and performance.<\/p>\n\n\n\n