Investigating Memory Usage Discrepancies
Warning
SingleStore 9.0 gives you the opportunity to preview, evaluate, and provide feedback on new and upcoming features prior to their general availability. In the interim, SingleStore 8.9 is recommended for production workloads, which can later be upgraded to SingleStore 9.0.
When there is a large discrepancy between the sum of memory usage from information_
vs what is reported in alloc_
, review the internal table statistics via information_
to see where the rest of memory is being held.
SHOW STATUS EXTENDED LIKE '%Alloc_table_memory%';
+--------------------+-----------------------+
| Variable_name | Value |
+--------------------+-----------------------+
| Alloc_table_memory | 39389.780 (+0.125) MB |
+--------------------+-----------------------+
1 row in set (0.00 sec)
Compare that information with the results of:
SELECT SUM(memory_use)/1024/1024/1024 MEM_GB FROM information_schema.table_statisticsWHERE 1=1 AND host = 'leaf-1.example.com';
+----------------+
| MEM_GB |
+----------------+
| 2.392731554806 |
+----------------+
1 row in set (0.76 sec)
The alloc variable is showing 39 GB while table statistics shows just 2.
The next step would be to examine the md_
<table> information in information_
for outliers to see where the rest of the memory is being held.md_
storing large amounts of data for each node.
Last modified: July 25, 2023