The XTRADB_INTERNAL_HASH_TABLES table provides memory usage statistics for internal hash tables used by the XtraDB/InnoDB storage engine.
The Information Schema XTRADB_INTERNAL_HASH_TABLES table contains InnoDB/XtraDB hash table memory usage information.
The PROCESS privilege is required to view the table.
It has the following columns:
INTERNAL_HASH_TABLE_NAME
Hash table name
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TOTAL_MEMORY
Total memory
CONSTANT_MEMORY
Constant memory
VARIABLE_MEMORY
Variable memory
SELECT * FROM information_schema.XTRADB_INTERNAL_HASH_TABLES;
+--------------------------------+--------------+-----------------+-----------------+
| INTERNAL_HASH_TABLE_NAME | TOTAL_MEMORY | CONSTANT_MEMORY | VARIABLE_MEMORY |
+--------------------------------+--------------+-----------------+-----------------+
| Adaptive hash index | 2217568 | 2213368 | 4200 |
| Page hash (buffer pool 0 only) | 139112 | 139112 | 0 |
| Dictionary Cache | 613423 | 554768 | 58655 |
| File system | 816368 | 812272 | 4096 |
| Lock System | 332872 | 332872 | 0 |
| Recovery System | 0 | 0 | 0 |
+--------------------------------+--------------+-----------------+-----------------+These system tables provide metadata about XtraDB tables, including their storage, statistics, and other properties for advanced analysis and management.
The XTRADB_RSEG table contains detailed information about the rollback segments used by XtraDB for undo logging and MVCC.
The Information Schema XTRADB_RSEG table contains information about the XtraDB rollback segments.
The PROCESS privilege is required to view the table.
It has the following columns:
rseg_id
Rollback segment id.
space_id
The number of records will match the value set in the variable (by default 128).
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The XTRADB_INTERNAL_HASH_TABLES table provides memory usage statistics for internal hash tables used by the XtraDB/InnoDB storage engine.
The CHANGED_PAGE_BITMAPS table is a dummy table added to with reset_table callback to allow FLUSH NO_WRITE_TO_BINLOG CHANGED_PAGE_BITMAPS to be called from innobackupex. It contains only one column, dummy.
For more information, see .
The PROCESS is required to view the table.
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Space where the segment is placed.
zip_size
Size in bytes of the compressed page size, or zero if uncompressed.
page_no
Page number of the segment header.
max_size
Maximum size in pages.
curr_size
Current size in pages.
The XTRADB_READ_VIEW table displays the current MVCC read views, showing which transactions are visible to active queries.
The Information Schema XTRADB_READ_VIEW table contains information about the oldest active transaction in the system.
The PROCESS privilege is required to view the table.
It has the following columns:
READ_VIEW_UNDO_NUMBER
READ_VIEW_LOW_LIMIT_TRX_NUMBER
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Highest transaction number at the time the view was created.
READ_VIEW_UPPER_LIMIT_TRX_ID
Highest transaction ID at the time the view was created. Should not see newer transactions with IDs equal to or greater than the value.
READ_VIEW_LOW_LIMIT_TRX_ID
Latest committed transaction ID at the time the oldest view was created. Should see all transactions with IDs equal to or less than the value.