{"id":3691,"date":"2025-05-29T12:53:00","date_gmt":"2025-05-29T12:53:00","guid":{"rendered":"https:\/\/w3buddy.com\/?post_type=cposts&p=3691"},"modified":"2025-05-29T12:53:01","modified_gmt":"2025-05-29T12:53:01","slug":"shared-pool","status":"publish","type":"cposts","link":"https:\/\/w3buddy.com\/blog\/notes\/getting-started-with-oracle-dba\/shared-pool\/","title":{"rendered":"Shared Pool"},"content":{"rendered":"\n

\ud83e\udde0 Introduction<\/strong>
The Shared Pool is a vital part of the System Global Area (SGA) in an Oracle Database instance. It caches parsed SQL, PL\/SQL code, system parameters, and data dictionary info, helping speed up query execution and reduce repetitive work.<\/p>\n\n\n\n

Almost every database operation relies on the Shared Pool to perform efficiently.<\/p>\n\n\n\n

\ud83e\udde9 Key Subcomponents of the Shared Pool<\/strong><\/p>\n\n\n\n

    \n
  1. Library Cache<\/strong><\/li>\n<\/ol>\n\n\n\n
      \n
    • Stores executable SQL and PL\/SQL code, including shared SQL areas, PL\/SQL areas, and control structures.<\/li>\n\n\n\n
    • When you run a SQL statement, Oracle tries to reuse an existing parsed version (soft parse) to save time.<\/li>\n\n\n\n
    • If no match is found, it does a hard parse, which creates a new execution plan but costs more time.<\/li>\n<\/ul>\n\n\n\n
        \n
      1. Reserved Pool<\/strong><\/li>\n<\/ol>\n\n\n\n
          \n
        • Allocates large chunks of memory inside the shared pool for big objects (over 5 KB).<\/li>\n\n\n\n
        • Prevents fragmentation by efficiently loading large objects.<\/li>\n<\/ul>\n\n\n\n
            \n
          1. Data Dictionary Cache<\/strong><\/li>\n<\/ol>\n\n\n\n
              \n
            • Also called the row cache.<\/li>\n\n\n\n
            • Stores metadata about tables, indexes, users, and more.<\/li>\n\n\n\n
            • Reduces disk reads by keeping this info in memory.<\/li>\n<\/ul>\n\n\n\n
                \n
              1. Server Result Cache<\/strong><\/li>\n<\/ol>\n\n\n\n
                  \n
                • Caches results of queries and PL\/SQL functions.<\/li>\n\n\n\n
                • Useful for speeding up repeated queries that depend on relatively static data.<\/li>\n<\/ul>\n\n\n\n

                  \ud83e\udde9 Other Shared Pool Components<\/strong><\/p>\n\n\n\n

                    \n
                  • Enqueues<\/strong>: Locks in shared memory that control access to resources (like recovery and job queues).<\/li>\n\n\n\n
                  • Latches<\/strong>: Lightweight locks preventing concurrent access to shared data structures (e.g., cache buffers chains).<\/li>\n\n\n\n
                  • ASH Buffers<\/strong>: Store Active Session History info for performance monitoring.<\/li>\n\n\n\n
                  • ILM Bitmap Tables<\/strong>: Track data access patterns for Information Lifecycle Management (ILM).<\/li>\n<\/ul>\n\n\n\n

                    \ud83d\udee0\ufe0f DBA Tip of the Day<\/strong>
                    Monitoring the shared pool hit ratio helps you understand how often Oracle reuses cached SQL vs. parsing new statements. A high hit ratio means better performance!<\/p>\n","protected":false},"excerpt":{"rendered":"

                    \ud83e\udde0 IntroductionThe Shared Pool is a vital part of the System Global Area (SGA) in an Oracle Database instance. It caches parsed SQL, PL\/SQL code, system parameters, and data dictionary info, helping speed up query execution and reduce repetitive work. Almost every database operation relies on the Shared Pool to perform efficiently. \ud83e\udde9 Key Subcomponents […]<\/p>\n","protected":false},"template":"","meta":{"googlesitekit_rrm_CAowu461DA:productID":""},"categories":[960,952],"class_list":["post-3691","cposts","type-cposts","status-publish","hentry","category-getting-started-with-oracle-dba","category-notes"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts\/3691","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/cposts"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=3691"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=3691"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}