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ORA-04301: unable to allocate x bytes of shared memory

Anyone consistently operating a company database has inevitably encountered the dreaded issue of insufficient memory space. Despite the regular increase in computational storage capacity, the issue remains a burden across all operating systems. The ORA-04031, an Oracle error regarding a specific memory problem in your database, falls within this realm. Fortunately, many version of Oracle are equipped with the proper tools to quickly assess and resolve this problem.


An ORA-04031 error message stems from a lack of available System Global Area (SGA) memory space (Note that this differs from Program Global Area (PGA), which correlates similarly with the ORA-04030 error). The error commonly occurs when working with large shared pools of memory.

If configured, large pools are set to a minimum of six hundred kilobytes, which is typically fine for Microsoft Transaction Server applications. Complexity arises when using a Parallel Query Option, which allows several processes to collect and sort records all at once, which can help maximize the benefits you receive from operating with speed and precision in Oracle. Determining the large pool size configured versus how much space your PQO is operating with can help in setting the stage for a solution to your error.


Considering this is an issue of pooled memory, your options are fairly straightforward. From one end of the spectrum, you can reduce your use of shared memory, which will nullify the causation of the error. On the other hand, you can also utilize the dbms_shared_pool package to pin large memory packages, or increase the availability of shared memory completely.

You can run the following select procedure to determine the current size of the pool in relation to what the maximum size of the pool can be (specified by the parameter LARGE_POOL_SIZE_):



SUM (bytes)





group by


Accordingly, you can then elevate the LARGE_POOL size up to a peak of 100% to eliminate the memory pool shortage causing the error. This will provide you with the space necessary to continue functioning at the same rate configured prior to the trigger of the ORA-04031 error.

Looking forward

Working with updated software can provide aid by issuing tools to quickly manage memory issues like pool size. In Oracle8, the V$SGASTAT performance view has a POOL column for displaying the area where an item is currently stored. A summary select of this view allows a user to judge the size of the large pool area much more quickly than in the past. Contacting a licensed Oracle consultant can help your company decide how these types of shortcuts can benefit your current database experience.