xtstat
xtstat serve a monitorare le attività interne di PBXT.
xtstat interroga la tabella INFORMATION_SCHEMA.PBXT_STATISTICS. L'intervallo tra le interrogazioni può essere impostato attraverso l'opzione --delay, il cui valore predefinito è 1 secondo.
Per la maggioranza delle statistiche, xtstat mostra la differenza tra il valore ricevuto con l'ultima interrogazione e il precedente. Per esempio, se i byte scritti sono 1000, e all'ultima interrogazione erano 800, allora xtstat mostra 200. Questo significa che nell'ultimo intervallo di tempo sono stati scritti su disco 200 byte.
Usare xtstat
xtstat si invoca come segue:
$ xtstat [ opzioni ]
Per esempio, per aggiornarlo ogni 10 secondi:
xtstat -D10
Si noti che i contatori delle statistiche non vengono mai azzerati, nemmeno se avviene un rollback. Per esempio, se un'istruzione UPDATE
subisce un rollback, xtstat continuerà a indicare che un'istruzione UPDATE è stata eseguita (si veda stat-write, più sotto).
Se MariaDB si arresta o va in crash, xtstat cercherà di riconnettersi. xtstat può essere terminato con la combinazione di tasti CTRL-C.
Non tutte le statistiche sono disponibili, fino a quando PBXT non viene recuperato. In particolare, le statistiche relative ai thread in background di PBXT non sono disponibili (comprese sweep e chkpnt).
Command line options
xtstat options are as follows:
Option | Description |
|---|---|
-?, --help | Prints help text. |
-h, --host=value | Connect to host. |
-u, --user=value | User for login if not current user. |
-p, --password[=value] | Password to use when connecting to server. If password is not given it's asked from the tty. |
-d, --database=value | Database to be used (pbxt or information_schema required), default is information_schema |
-P, --port=value | Port number to use for connection. |
-S, --socket=value | Socket file to use for connection. |
-D, --delay=value | Delay in seconds between polls of the database. |
--protocol=value | Connection protocol to use: default/tcp/socket/pipe/memory |
--display=value | Columns to display: use short names separated by | (the pipe character), partial match allowed. Use --display=all to display all columns available. |
Connection options will also be taken from the MySQL config file if available.
Size indicators
Values displayed by xtstat are either a time in milliseconds, a value in bytes, or a counter. If these values are too large to be displayed then the value is rounded and a size indicator is added.
The following size indicators are used:
K | : | Kilobytes (1,024 bytes) |
M | : | Megabytes (1,048,576 bytes) |
G | : | Gigabytes (1,073,741,024 bytes) |
T | : | Terabytes (1,099,511,627,776 bytes) |
t | : | thousands (1,000s) |
m | : | millions (1,000,000s) |
b | : | billions (1,000,000,000s) |
Statistics
The following is a list of the statistics displayed by xtstat. Each statistic as a two-part display name. The first part is the category and the second part is the type.
You can select categories and types for display, as you require. For example --display=read will display all read activity, --display=xact|stat will display transaction and statement activity.
Note, for diagnostics it is best to capture all statistics. The reason is because you never now where a problem might turn up, so without certain statistics you may not be able to identify the problem.
| Display name | Name | Description |
|---|---|---|
time-curr | Current Time | The current time in seconds |
time-msec | Time Since Last Call | Time passed in milliseconds since last statistics call |
xact-commt | Commit Count | Number of transactions committed |
xact-rollb | Rollback Count | Number of transactions rolled back |
xact-waits | Wait for Xact Count | Number of times waited for another transaction |
xact-dirty | Dirty Xact Count | Number of transactions still to be cleaned up. This also includes all the currently running transactions. Cleanup means that the Sweeper thread must still scan the transcation and collect/mark any "garbage" left by the transaction. Garbage is, for example, versions of rows that are no longer visiable by any transaction. |
stat-read | Read Statements | Number of SELECT statements |
stat-write | Write Statements | Number of UPDATE/INSERT/DELETE statements |
rec-in | Record Bytes Read | Bytes read from the record/row files |
rec-out | Record Bytes Written | Bytes written to the record/row files. This data is transfered from the transaction logs to the handle data (xtd) and the row index files (xtr). |
rec-syncs/ms | Record File Flushes | 2 values separated by a '/': the number of flushes to data handle (.xtd) and row index (.xtr) files and the time taken in milliseconds to perform the flush operations. |
rec-hits | Record Cache Hits | Hits when accessing the record cache. The record cache caches the data handle (.xtd) and row index (.xtr) files. |
rec-miss | Record Cache Misses | Misses when accessing the record cache |
rec-frees | Record Cache Frees | Number of record cache pages freed |
rec-%use | Record Cache Usage | Percentage of record cache in use. This value is displayed by xtstat as a percentage of the total cache available, but the value returned by PBXT_STATISTICS table is in bytes used. |
ind-in | Index Bytes Read | Bytes read from the index files |
ind-out | Index Bytes Written | Bytes written to the index files. This data is transfered from the index log files (ilog) to the index files (xti), during a consistent flush of the index. |
ind-syncs/ms | Index File Flushes | 2 values separated by a '/': the number of flushes to index files and the time taken for the flush operations in milliseconds. |
ind-hits | Index Cache Hits | Hits when accessing the index cache |
ind-miss | Index Cache Misses | Misses when accessing the index cache |
ind-%use | Index Cache Usage | Percentage of index cache used. This value is displayed by xtstat as a percentage of the total cache available, but the value returned by PBXT_STATISTICS table is in bytes used. |
ilog-in | Index Log Bytes In | Bytes read from the index log files |
ilog-out | Index Log Bytes Out | Bytes written to the index log files. This data is transfered from the index cache in main memory to the index log files (ilog) during a consistent flush of the index. |
ilog-syncs/ms | Index Log File Syncs | 2 values separated by a '/': the number of flushes to index log files and the time taken for the flush operations in milliseconds |
xlog-in | Xact Log Bytes In | Bytes read from the transaction log files |
xlog-out | Xact Log Bytes Out | Bytes written to the transaction log files. This is data transfered from the transaction log buffer (pbxt_transaction_buffer_size) to the transaction log files (.xlog). This transfer occurs on commit or when the transaction log buffer is full. |
xlog-syncs | Xact Log File Syncs | Number of flushes to transaction log files |
xlog-msec | Xact Log Sync Time | The time in milliseconds to flush transaction log files |
xlog-hits | Xact Log Cache Hits | Hits when accessing the transaction log cache |
xlog-miss | Xact Log Cache Misses | Misses when accessing the transaction log cache |
xlog-%use | Xact Log Cache Usage | Percentage of transaction log cache used. This value is displayed by xtstat as a percentage of the total cache available, but the value returned by PBXT_STATISTICS table is in bytes used. |
data-in | Data Log Bytes In | Bytes read from the data log files |
data-out | Data Log Bytes Out | Bytes written to the data log files. This data is transfered from the data log buffer (pbxt_log_buffer_size) to the data log files (.dlog), when the buffer is full, or on commit. |
data-syncs | Data Log File Syncs | Number of flushes to data log files |
data-msec | Data Log Sync Time | The time in milliseconds spent flushing data log files |
to-chkpt | Bytes to Checkpoint | Bytes written to the transaction log since the last checkpoint |
to-write | Log Bytes to Write | Bytes written to the transaction log, still to be written to the database |
to-sweep | Log Bytes to Sweep | Bytes written to the transaction log, still to be read by the Sweeper thread |
sweep-waits | Sweeper Wait on Xact | Attempts to cleanup a transaction |
scan-index | Index Scan Count | Number of index scans |
scan-table | Table Scan Count | Number of table scans |
row-sel | Select Row Count | Number of rows selected |
row-ins | Insert Row Count | Number of rows inserted |
row-upd | Update Row Count | Number of rows updated |
row-del | Delete Row Count | Number of rows deleted |
More Information
Documentation on this page is based on the xtstat documentation on the PrimeBase website.
Paul McCullagh's presentation from the 2010 User's Conference has some usage examples: http://www.primebase.org/download/pbxt-uc-2010.pdf
