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Updated on 2024-06-03 GMT+08:00
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GS_SESSION_MEMORY_DETAIL

GS_SESSION_MEMORY_DETAIL displays the thread memory usage based on the MemoryContext node. When enable_thread_pool is set to on, this view contains memory usage of all threads and sessions. If the GUC parameter enable_memory_limit is set to off, this view is unavailable.

The memory context TempSmallContextGroup collects information about all memory contexts whose value in the totalsize column is less than 8192 bytes in the current thread, and the number of the collected memory contexts is recorded in the usedsize column. Therefore, the totalsize and freesize columns for TempSmallContextGroup in the view display the corresponding information about all the memory contexts whose value in the totalsize column is less than 8192 bytes in the current thread, and the usedsize column displays the number of these memory contexts.

You can run the SELECT * FROM gs_session_memctx_detail(threadid, ''); statement to record information about all memory contexts of a thread into the threadid_timestamp.log file in the $GAUSSLOG/gs_log/${node_name}/dumpmem directory. threadid can be obtained from sessid in the following table.

Table 1 GS_SESSION_MEMORY_DETAIL columns

Name

Type

Description

sessid

text
  1. When the thread pool is disabled (enable_thread_pool = off), this column indicates the thread start time + session ID (string: timestamp.sessionid).
  2. When the thread pool is enabled (enable_thread_pool = on): If the memory context is at the thread level, this column indicates the thread start time + thread ID (string: timestamp.threadid). If the memory context is at the session level, the column indicates the thread start time + session ID (string: timestamp.sessionid).

sesstype

text

Thread name

contextname

text

Name of the memory context

level

smallint

Hierarchy of the memory context

parent

text

Name of the parent memory context

totalsize

bigint

Total size of the memory context, in bytes

freesize

bigint

Total size of released memory in the memory context, in bytes

usedsize

bigint

Size of used memory in the memory context, in bytes. For TempSmallContextGroup, this parameter specifies the number of collected memory contexts.

This view is an O&M view and is used to locate memory problems. Do not query this view concurrently. If you query this view concurrently, the waiting time for new connections increases as the number of concurrent connections increases. As a result, new connections cannot be connected for a long time.

Parent topic: Other System Views