# xtstat
{% hint style="warning" %}
This tool is for PBXT, an unsupported storage engine.
{% endhint %}
`xtstat` can be used to monitor all internal activity of PBXT (a storage engine that is no longer supported).
`xtstat` polls the `INFORMATION_SCHEMA.PBXT_STATISTICS` table. The poll interval can be set using the `--delay` option, and is 1 second by default.
For most statistics, `xtstat` will display the difference in values between the current and previous polls. For example, if bytes written current value is 1000, and on the previous call it was 800, then `xtstat` will display 200. This means that 200 bytes were written to disk in the intervening period.
## Using `xtstat`
Invoke xtstat as follows:
```bash
$ xtstat [ options ]
```
For example, to poll every 10 seconds:
```bash
xtstat -D10
```
Note that statistic counters are never reset, even if a rollback occurs. For example, if an `UPDATE` statement is rolled back, `xtstat` will still indicate that one write statement (see stat-write below) was executed.
If MariaDB shuts down or crashes, `xtstat` will attempt to reconnect. `xtstat` can be terminated any time using the `CTRL-C` key cimbination.
Before PBXT has recovered, not all statistics are available. In particular, the statistics relating to PBXT background threads are not available (including the `sweep` and `chkpnt` statistics).
### 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 |
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 |
| ------------- | --------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 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](https://primebase.org/documentation/index.php#xtstat) on the PrimeBase website.
Paul McCullagh's presentation from the 2010 User's Conference has some usage examples: [pbxt-uc-2010.pdf](https://www.primebase.org/download/pbxt-uc-2010.pdf)
*This page is licensed: CC BY-SA / Gnu FDL*
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