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TDSQL-C for MySQL

Supported Monitoring Metrics

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Last updated: 2026-07-06 18:00:58
AI-Translated
TDSQL-C for MySQL provides monitoring metrics from the dimensions of secondary instances and database proxy nodes.
Note:
The monitoring metrics data below can be viewed through the console or TencentCloud API. For how to view them, see Viewing Monitoring Data.
Parallel query monitoring metrics are supported in TDSQL-C for MySQL 8.0 kernel version 3.1.8 and above.
Columnar storage index monitoring metrics are supported in TDSQL-C for MySQL 8.0 kernel version 3.1.14.
For monitoring metrics related to the read-only analysis engine, see Viewing Monitoring Data.
Secondary cache monitoring metrics are supported in TDSQL-C for MySQL 5.7 kernel version 2.1.13.002 and above, and 8.0 kernel version 3.1.15.002 and above.
When you obtain monitoring data through calling APIs, the monitoring metric names used in the call parameter items should follow the Callable Metric Name column in the table below.

Monitoring Metrics Instances

Category
Monitoring Metric Name
Callable Metric Name
Unit
Data Aggregation Method
Resource Monitoring
CPU Utilization
CpuUseRate
%
MAX
Memory Utilization
MemoryUseRate
%
MAX
Used Memory
MemoryUse
MB
MAX
Level-1 Storage Utilization
StorageUseRate
%
MAX
Level-1 Storage Usage
StorageUse
GB
MAX
Level-2 Storage Usage
ArchiveStorageUsed
GB
MAX
Used Data Tablespace
DataVolumeUsage
GB
MAX
Used Temp Tablespace
TmpVolumeUsage
GB
MAX
Used Undo Tablespace
UndoVolumeUsage
GB
MAX
CCU
Ccu
pcs
MAX
Traffic Inbound to Client per Second
BytesSent
MB/second
MAX
Traffic Outbound from Client per Second
BytesReceived
MB/second
MAX
Read Request IOPS
Readiops
Counts/second
MAX
Write Request IOPS
Writeiops
Counts/second
MAX
Total IOPS
Iops
Counts/second
MAX
Read I/O Throughput
ReadBandwidth
MB/second
MAX
Write I/O Throughput
WriteBandwidth
MB/second
MAX
Total I/O Throughput
IoBandwidth
MB/second
MAX
Storage Space Used by Logs
LogCapacity
GB
MAX
Alive Status
AliveStatus
0 - Alive
1 - Abnormal
MAX
Read-write instance write status
ReadOnly
0 - Normal
1 - Abnormal
MAX
OOM status
MemoryOOM
0 - No, 1 - Yes
MAX
Memory Cache Usage
MemoryStatCache
MB
MAX
Number of Used Precompiled Statements
PreparedStmtCount
pcs
MAX
Precompiled Statement Utilization
PreparedStmtCountUseRate
%
MAX
Engine monitoring
Connection
Queries per Second
Qps
Counts/second
MAX
Transactions per Second
Tps
Counts/second
MAX
Connection Utilization
ConnectionUseRate
%
MAX
Max Connections
MaxConnections
pcs
MAX
Open Connections
ThreadsConnected
pcs
MAX
Created Threads
ThreadsCreated
pcs
SUM
Running Threads
ThreadsRunning
pcs
MAX
Cumulative Number of Connections
Connections

MAX
Access
Slow Queries
SlowQueries
pcs
SUM
Full-Table Scans
SelectScan
pcs
SUM
SELECT Statements
ComSelect
pcs
SUM
UPDATE Statements
ComUpdate
pcs
SUM
DELETE Statements
ComDelete
pcs
SUM
INSERT Statements
ComInsert
pcs
SUM
REPLACE Queries
ComReplace
pcs
SUM
Total Queries
Queries
pcs
SUM
COMMIT Statements
ComCommit
pcs
SUM
Rollbacks
ComRollback
pcs
SUM
Full-Table Scan Joins
SelectFullJoin
pcs
SUM
Range Scan Joins
SelectFullRangeJoin
pcs
SUM
Sort Merges
SortMergePasses
pcs
SUM
Qcache Hit Rate
QcacheHitRate
%
MIN
Qcache Utilization
QcacheUseRate
%
MIN
Multi-Table UPDATE Statements
ComUpdateMulti
pcs
SUM
Multi-Table DELETE Statements
ComDeleteMulti
pcs
SUM
DDL throughput
DDLTps
counts/sec
MAX
Number of client requests
Questions
counts/cycle
SUM
Total number of sorted rows
SortRows
Rows
MAX
Number of Optimize commands
ComOptimize
counts/cycle
SUM
Number of Analyze commands
ComAnalyze
counts/cycle
SUM
Cumulative execution frequency of prepared statements
ComStmtExecute
counts/sec
MAX
Cumulative preparation frequency of prepared statements
ComStmtPrepare
counts/sec
MAX
INSERT_SELECT
ComInsertSelect
counts/sec
MAX
REPLACE_SELECT
ComReplaceSelect
counts/sec
MAX
Table count
ComCreateTable
counts/sec
SUM
Modify Table Count
ComAlterTable
counts/sec
SUM
Number of Table Deletions
ComDropTable
counts/sec
SUM
Clear table count
ComTruncate
counts/sec
SUM
Number of Index Deletions
ComDropIndex
counts/sec
SUM
Delete number of users
ComDropUser
counts/sec
SUM
Table
Temp Tables
CreatedTmpTables
pcs
SUM
Table Lock Waits
TableLocksWaited
pcs
SUM
Opened Tables
OpenedTables
pcs
MAX
Table Locks Released Immediately
TableLocksImmediate
pcs
SUM
Open Table Cache Hits
TableOpenCacheHits
pcs
SUM
Open Table Cache Misses
TableOpenCacheMisses
pcs
SUM
temporary table utilization
TmpTablesRate
%
MAX
table open cache overflows
TableOpenCacheOverflows

MAX
InnoDB
InnoDB Cache Hit Rate
InnodbCacheHitRate
%
MIN
InnoDB Cache Utilization
InnodbCacheUseRate
%
MIN
Disk Reads
InnodbOsFileReads
pcs
MAX
Disk Writes
InnodbOsFileWrites
pcs
MAX
InnoDB_fsyncs
InnodbOsFsyncs
pcs
MAX
Tables Opened by InnoDB
InnodbNumOpenFiles
pcs
MAX
Data Read in InnoDB
InnodbDataRead
Byte
SUM
Total InnoDB Reads
InnodbDataReads
pcs
SUM
Total InnoDB Writes
InnodbDataWrites
pcs
SUM
Data Written in InnoDB
InnodbDataWritten
Byte
SUM
Rows Deleted from InnoDB Tables
InnodbRowsDeleted
pcs
SUM
Rows Inserted to InnoDB Tables
InnodbRowsInserted
pcs
SUM
Rows Updated in InnoDB Tables
InnodbRowsUpdated
pcs
SUM
Rows Read from InnoDB Tables
InnodbRowsRead
pcs
SUM
Avg Time to Get an InnoDB Row Lock
InnodbRowLockTimeAvg
Milliseconds
MAX
InnoDB Row Lock Waits
InnodbRowLockWaits
pcs
SUM
InnoDB Dirty Pages
InnodbBufferPoolPagesDirty
pcs
MAX
Writes in InnoDB Suspension
InnodbDataPendingWrites
pcs
MAX
Reads in InnoDB Suspension
InnodbDataPendingReads
pcs
MAX
Waiting Writes for InnoDB Log
InnodbLogWaits
pcs
SUM
Physical Writes for InnoDB Log
InnodbLogWrites
pcs
SUM
Physical Write Requests for InnoDB Log
InnodbLogWriteRequests
pcs
SUM
InnoDB pages read per second
InnodbReadPages
counts/sec
MAX
InnoDB pages written per second
InnodbWritePages
counts/sec
MAX
InnoDB data pages
InnodbBufferPoolDataPages
pages
MAX
InnoDB write wait page number
InnodbBufferPoolWaitFree
pcs
MAX
transaction history list length
TrxRsegHistoryLen
pcs
MAX
Tmp
Temp Tables
CreatedTmpDiskTables
pcs
SUM
Temp Files
CreatedTmpFiles
pcs
SUM
Handler
Requests to Read Next Row
HandlerReadRndNext
pcs
SUM
Rollbacks Performed in Storage Engine
HandlerRollback
pcs
SUM
Internal COMMIT Statements
HandlerCommit
pcs
SUM
Buffer
InnoDB Free Pages
InnodbBufferPoolPagesFree
pcs
MAX
Total InnoDB Pages
InnodbBufferPoolPagesTotal
pcs
MAX
InnoDB Logical Reads
InnodbBufferPoolReadRequests
pcs
SUM
InnoDB Physical Reads
InnodbBufferPoolReads
pcs
SUM
Writes in InnoDB Buffer Pool
InnodbBufferPoolWriteRequest
pcs
SUM
Parallel query
Parallelly Queried Threads
TxsqlParallelThreadsCurrentlyUsed
pcs
MAX
Failed Parallel Queries
TxsqlParallelStmtError
pcs
SUM
Executed Parallel Queries
TxsqlParallelStmtExecuted
pcs
SUM
Parallel-to-Serial Queries
TxsqlParallelStmtFallback
pcs
SUM
Columnar storage indexes
Executed Statements for ColumnStore Index
InnodbCsiSelectPushdown
pcs
SUM
Unexecuted Statements for ColumnStore Index
InnodbCsiSelectFallback
pcs
SUM
Sync Delay for ColumnStore Index
InnodbCsiLagSeconds
Second
MAX
Storage Usage for ColumnStore Index
InnodbCsiDiskUsage
GB
MAX
Failed CSI Creations
InnodbCsiCreateFailed
pcs
SUM
Secondary cache
BP pages read from secondary cache
InnodbNcdbScReadFromSc
pcs
SUM
BP pages read from storage
InnodbNcdbScReadFromCbs
pcs
SUM
Pages evicted from secondary cache
InnodbNcdbScWriteWithoutFlush
pcs
SUM
Pages invalidated in secondary cache
InnodbNcdbScFreeByLru
pcs
SUM
Pages used in secondary cache
InnodbNcdbScUsedPageNum
pcs
SUM
Secondary cache storage usage
InnodbNcdbScUsage
GB
MAX
Secondary cache storage utilization
InnodbNcdbScUseRate
%
MAX
Others
Total Opened File
OpenFiles
pcs
MAX
Query of cache hit coun
QcacheHits
pcs
SUM
Search for cache count
QcacheSearchTimes
pcs
SUM
Query of total cache count
QcacheTotalTimes
pcs
SUM
Query of remaining cache space
QcacheFreeMemory
MB
MAX
Successful result set cache coun
QcacheInserts
pcs
SUM
Failed result set cache count
QcacheNotCached
pcs
SUM
Cached query count
QcacheQueriesInCache
pcs
SUM
Eliminated query count
QcacheLowmemPrunes
pcs
SUM
Deployment monitoring
Replication Status
ReplicationStatus
0-Yes,1-No
Take 1 if any is 1
Replication Delay
ReplicationDelay
Milliseconds
MAX
Replication lag in lsn distance
ReplicationDelayDistance
Bytes
MAX
Cross-AZ primary/secondary synchronization gap
MasterSlaveSyncDistance
MB
MAX
IO thread status for cross-AZ deployment
ClusterSlaveIoRunning
0 - Yes
1 - No
2 - Connecting
MAX
SQL thread status for cross-AZ deployment
ClusterSlaveSqlRunning
0 - Yes
1 - No
MAX
Cross-AZ latency
SecondsBehindMaster
Second
MAX
Transaction wait time for cross-AZ cluster acknowledgment
RplSemiSyncMasterTxCurWaitTime
μs
MAX
Pending replication log volume (MB)
ReplicaLagMaxLogMb
MB
MAX
Pending replication log volume (LSN)
ReplicaLagMaxLog
Bytes
MAX

Database Proxy Node Monitoring Metrics

To obtain monitoring metrics for the database proxy node dimension, you must first enable the database proxy. For detailed metric descriptions, see Viewing Database Proxy Monitoring.

Performance Monitoring Metrics Analysis Practice

You can monitor and analyze relevant performance metrics by setting up alarm policies. The following examples introduce several metrics to analyze monitoring data.
CPU Utilization: CPU utilization refers to the usage rate of the CPU in the database server during operation. High CPU load can lead to issues such as slow database system response and query latency. Therefore, you can set threshold alarms for this monitoring metric based on actual business conditions. Generally, when CPU utilization exceeds 90%, you need to start paying attention to whether the request volume the database needs to handle is too high, whether query performance is optimized, and make timely adjustments. If the CPU consumption value meets the goals of the application or database (such as throughput or concurrency) and is expected, then this value is appropriate.
Storage Usage: If the used space consistently equals or exceeds 85% of the total disk space, you need to investigate the storage consumption. Check whether data can be deleted from the instance or archived to another system to free up space. If the stored data volume is too large and the disk is about to become full, you can alleviate the insufficient disk space issue through scale-out.
Client Send and Receive Traffic: By observing fluctuations in the monitoring metrics - Resource Monitoring - for client send or receive traffic data, you can check whether the issue is caused by a business peak or a database problem, and then perform business optimization or database configuration adjustments accordingly.
Maximum Number of Connections: max_connections is one of the parameters in TDSQL-C for MySQL, used to specify the maximum number of connections allowed by the database simultaneously. When the database process opens a new connection, it queries the number of currently connected clients. If the number has reached the set value of max_connections, a new connection cannot be established. If you observe a large number of connections through monitoring and the instance performance and response time have also decreased, consider constraining the maximum number of database connections. If the value of max_connections is set too high, it may cause issues such as insufficient memory or thread crashes. Therefore, carefully evaluate the needs of the application and perform optimal configuration. The commonly used configuration value is between 200 and 500. Also, adjust the maximum number of connections based on the actual connection situation of the application and the database.
When performance metrics exceed the set alarm threshold, you may need to modify relevant parameters to optimize the database, thereby helping to improve its performance and availability.

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