Monitoring database performance

Reference Manual
APPENDIX A. Database Performance and Connection Properties

Monitoring database performance

Adaptive Server Anywhere provides a set of statistics that can be used to monitor database performance. These are accessible from Sybase Central, and client applications can access the statistics as functions. In addition, these statistics are made available by the server to the Windows NT performance monitor.

This section describes how to access performance and related statistics from client applications, how to monitor database performance using Sybase Central, and how to monitor database performance using the Windows NT performance monitor.

Obtaining database statistics from a client application

Adaptive Server Anywhere provides a set of system functions that can access information on a per-connection, per-database, or engine-wide basis. The kind of information available ranges from static information such as the server name to detailed performance-related statistics concerning disk and memory usage.

The performance-related statistics are also available, along with some other statistics, for the Windows NT engine and server in the Windows NT Performance Monitor.

For more information on the Performance Monitor, see Monitoring database statistics from the Windows NT Performance Monitor.

This section illustrates how to use the functions.

A complete list of system functions and of their properties is provided in the section System functions.

Functions that retrieve system information

The following functions are used to retrieve system information:

property Provides the value of a given property on an engine-wide basis
connection_property Provides the value of a given property for a given connection, or for the current connection by default.
db_property Provides the value of a given property for a given database, or for the current database by default.

Supply as an argument only the name of the property you wish to retrieve, the functions return the value for the current server, connection, or database.

Examples

The following statement sets a variable named server_name to the name of the current server:
```
SET server_name = property( 'name' )
```
The following query returns the user ID for the current connection:
```
SELECT connection_property( 'userid' )
```
The following query returns the filename for the root file of the current database:
```
SELECT db_property( 'file' )
```

Improving query efficiency

For maximum efficiency, a client application monitoring database activity should use the property_number function to identify a named property, and then use the number to repeatedly retrieve the statistic. The following set of statements illustrates the process from Interactive SQL:

CREATE VARIABLE propnum INT ;
CREATE VARIABLE propval INT ;
SET propnum = property_number( 'cacheread' );
SET propval = property( propnum )

Property names obtained in this way are available for many different database statistics, from the number of transaction log page write operations and the number of checkpoints carried out to the number of reads of index leaf pages from the memory cache.

Many of these statistics are made available in graphical form from the Sybase Central database management tool.

Monitoring database statistics from Sybase Central

You can monitor database statistics from Sybase Central. The Sybase Central Performance Monitor is a graphing tool that can present database statistics as a line graph or a bar graph.

To start the Sybase Central Performance Monitor:

Click the icon for the server you wish to monitor in the left panel.
Double-click the Statistics folder underneath the server.
Select a statistic to graph, and drag it to the Performance Monitor icon to start graphing that statistic.

About the performance monitor

The Performance Monitor uses the regular Adaptive Server Anywhere communication mechanisms to gather statistics. This means some statistics (most notably Cache Reads) are affected by Sybase Central. For example, graphing Cache Reads/sec in Sybase Central shows a steady rate, even when nothing apart from the monitoring is going on.

If you have a Windows NT client and server, the Windows NT Performance monitor is preferable since it offers more statistics, and is not intrusive: updating the statistics will not affect the measurements. The extra statistics the Windows NT performance monitor offers deal mainly with network communications—packets received, network buffers used, and so on.

Monitoring database statistics from the Windows NT Performance Monitor

The Windows NT performance monitor is an application for viewing the behavior of objects such as processors, memory, and applications. Adaptive Server Anywhere provides many statistics for the performance monitor to display.

The Windows NT performance monitor allows unintrusive monitoring of statistics: updating the statistics does not affect the measurements.

To start the Windows NT performance monitor:

Open the Administrative Tools program group.
Double click Performance Monitor.

For information about Performance Monitor, see the Performance Monitor online Help.

To display database statistics:

With Performance Monitor running, select Add To Chart from the Edit menu, or click the Plus sign on the toolbar.

The Add To Chart dialog appears.
From the Object list, select Adaptive Server Anywhere.

The Counter list then displays a list of the statistics provided.
From the Counter list, click a statistic to be displayed.
For a description of the selected counter, click Explain.
To display the counter, click Add.
When you have selected all the counters you wish to display, click Done.

Performance Monitor statistics

The statistics made available for Performance Monitor by Adaptive Server Anywhere are as follows:

Statistic

Description

Active Requests

Active Requests is the number of engine threads that are currently handling a request.

Asynchronous Reads/sec

Asynchronous Reads/sec is the rate at which pages are being read asynchronously from disk.

Asynchronous Writes/sec

Asynchronous Writes/sec is the rate at which pages are being written asynchronously to disk.

Bytes Received/sec

Bytes Received/sec is the rate at which network data (in bytes) are being received.

Bytes Transmitted/sec

Bytes Transmitted/sec is the rate at which bytes are being transmitted over the network.

Cache Hits/sec

Cache Hits/sec is the rate at which database page lookups are satisfied by finding the page in the cache.

Cache Index Internal Reads/sec

Cache Index Internal Reads/sec is the rate at which index internal-node pages are being read from the cache.

Cache Index Leaf Reads/sec

Cache Index Leaf Reads/sec is the rate at which index leaf pages are being read from the cache.

Cache Reads/sec

Cache Reads/sec is the rate at which database pages are being looked up in the cache.

Cache Table Reads/sec

Cache Table Reads/sec is the rate at which table pages are being read from the cache.

Cache Writes/sec

Cache Writes/sec is the rate at which pages in the cache are being modified (in pages/sec).

Checkpoint Flushes/sec

Checkpoint Flushes/sec is the rate at which ranges of adjacent pages are being written out during a checkpoint.

Checkpoint Log/sec

Checkpoint Log/sec is the rate at which the transaction log is being checkpointed.

Checkpoint Urgency

Checkpoint Urgency is expressed as a percentage.

Checkpoints/sec

Checkpoints/sec is the rate at which checkpoints are being performed.

Commit files/sec

Commit files/sec is the rate at which the engine is forcing a flush of the disk cache. On Windows NT and NetWare platforms, the disk cache does not need to be flushed because unbuffered (direct) I/O is used.

Commits/sec

Commits/sec is the rate at which Commit requests are being handled.

Context Switch Checks/sec

Context Switch Checks/sec is the rate at which the current engine thread is volunteering to give up the CPU to another engine thread.

Context Switches/sec

Context Switches/sec is the rate at which the current engine thread is being changed.

Continue Requests/sec

Continue Requests/sec is the rate at which "CONTINUE" requests are being issued to the engine.

Corrupt Packets/sec

Corrupt Packets/sec is the rate at which corrupt network packets are being received.

Current IO

Current IO is the current number of file I/Os issued by the engine which have not yet completed.

Current Reads

Current Reads is the current number of file reads issued by the engine which have not yet completed.

Current Writes

Current Writes is the current number of file writes issued by the engine which have not yet completed.

Cursor

Cursor is the number of declared cursors that are currently being maintained by the engine.

Dirty Pages

Dirty Pages is the number of pages in the cache which must be written out and which do not belong to temporary files.

Disk Index Internal Reads/sec

Disk Index Internal Reads/sec is the rate at which index internal-node pages are being read from disk.

Disk Index Leaf Reads/sec

Disk Index Leaf Reads/sec is the rate at which index leaf pages are being read from disk.

Disk Reads/sec

Disk Reads/sec is the rate at which pages are being read from file.

Disk SyncReads/sec

Disk SyncReads/sec is the rate at which pages are being read synchronously from disk.

Disk SyncWrite Other/sec

Disk SyncWrite Other/sec is the rate at which pages are being written synchronously to disk for a reason not covered by other "Disk SyncWrites _____/sec" counters.

Disk SyncWrites Checkpoint/sec

Disk SyncWrites Checkpoint/sec is the rate at which pages are being written synchronously to disk for a checkpoint.

Disk SyncWrites Extend/sec

Disk SyncWrites Extend/sec is the rate at which pages are being written synchronously to disk while extending a database file.

Disk SyncWrites Free Current/sec

Disk SyncWrites Free Current/sec is the rate at which pages are being written synchronously to disk to free a page that cannot remain in the in-memory free list.

Disk SyncWrites Free Push/sec

Disk SyncWrites Free Push/sec is the rate at which pages are being written synchronously to disk to free a page that can remain in the in-memory free list.

Disk SyncWrites Log/sec

Disk SyncWrites Log/sec is the rate at which pages are being written synchronously to the transaction log.

Disk SyncWrites Rollback/sec

Disk SyncWrites Rollback/sec is the rate at which pages are being written synchronously to the rollback log.

Disk SyncWrites/sec

Disk SyncWrites/sec is the rate at which pages are being written synchronously to disk. It is the sum of all the other "Disk SyncWrites _____/sec" counters.

Disk Table Reads/sec

Disk Table Reads/sec is the rate at which table pages are being read from disk.

Disk Waitreads/sec

Disk Waitreads/sec is the rate at which the engine is waiting synchronously for the completion of a read IO operation which was originally issued as an asynchronous read. Waitreads often occur due to cache misses on systems that support asynchronous IO.

Disk Waitwrites/sec

Disk Waitwrites/sec is the rate at which the engine is waiting synchronously for the completion of a write IO operation which was originally issued as an asynchronous write.

Disk Writes/sec

Disk Writes/sec is the rate at which modified pages are being written to disk.

Dropped Packets/sec

Dropped Packets/sec is the rate at which network packets are being dropped due to lack of buffer space.

Extend Database/sec

Extend Database/sec is the rate (in pages/sec) at which the database file is being extended.

Extend Temporary File/sec

Extend Temporary File/sec is the rate (in pages/sec) at which temporary files are being extended.

Free Buffers

Number of free network buffers.

Freelist Write Current/sec

Freelist Write Current/sec is the rate at which pages that cannot remain in the in-memory free list are being freed.

Freelist Write Push/sec

Freelist Write Push/sec is the rate at which pages that can remain in the in-memory free list are being freed.

Full compares/sec

Full compares/sec is the rate at which comparisons beyond the hash value in an index must be performed.

IO to Recover

IO to Recover is the estimated number of IO operations required to recover the database.

Idle Active/sec

Idle Active/sec is the rate at which the engine's idle thread becomes active to do idle writes, idle checkpoints, etc.

Idle Checkpoints/sec

Idle Checkpoints/sec is the rate at which checkpoints are completed by the engine's idle thread. An idle checkpoint occurs whenever the idle thread writes out the last dirty page in the cache.

Idle Waits/sec

Idle Waits/sec is the number of times per second that the server goes idle waiting for IO completion or a new request.

Idle Writes/sec

Idle Writes/sec is the rate at which disk writes are being issued by the engine's idle thread.

Index Fills

Index Fills is the number of times a new temporary merge index is created.

Index Merges

Index Merges is the number of times a temp index has been merged into a main index

Index adds/sec

Index adds/sec is the rate at which entries are being added to indexes.

Index lookups/sec

Index lookups/sec is the rate at which entries are being looked up in indexes.

Lock Table Pages

Lock Table Pages is the number of pages used to store lock information.

Main Heap Pages

Main Heap Pages is the number of pages used for global engine data structures.

Map Pages

Map Pages is the number of map pages used for accessing the lock table, frequency table, and table layout.

Maximum IO

Maximum IO is the maximum value that "Current IO" has reached.

Maximum Reads

Maximum Reads is the maximum value that "Current Reads" has reached.

Maximum Writes

Maximum Writes is the maximum value that "Current Writes" has reached.

Multi-packets Received/sec

Multi-packets Received/sec is the rate at which multi-packet deliveries are being received.

Multi-packets Transmitted/sec

Multi-packets Transmitted/sec is the rate at which multi-packet deliveries are being transmitted.

Open cursors

Open cursors is the number of open cursors that are currently being maintained by the engine.

Packets Received/sec

Packets Received/sec is the rate at which network packets are being received.

Packets Transmitted/sec

Packets Transmitted/sec is the rate at which network packets are being transmitted.

Page Relocations/sec

Page Relocations/sec is the rate at which relocatable heap pages are being read from the temporary file.

Pending requests/sec

Pending requests/sec is the rate at which the engine is detecting the arrival of new requests.

Ping1/sec

Ping1/sec is the rate at which ping requests which go all the way down into the engine are serviced.

Ping2/sec

Ping2/sec is the rate at which ping requests which are turned around at the top of the protocol stack are serviced.

Procedure Pages

Procedure Pages is the number of relocatable heap pages used for procedures.

Read Hints Used/sec

Read Hints Used/sec is the rate at which page-read operations are being satisfied immediately from cache thanks to an earlier read hint.

Read Hints/sec

A read hint is an asynchronous read operation for a page that the server is likely to need soon. Read Hints/sec is the rate at which such read operations are being issued.

Recovery Urgency

Recovery Urgency is expressed as a percentage.

Redo Free Commits/sec

A "Redo Free Commit" occurs when a commit of the transaction (redo) log is requested but the log has already been written (so the commit was done for "free").

Redo Rewrites/sec

Redo Rewrites/sec is the rate at which pages that were previously written to the transaction log (but were not full) are being written to the transaction log again (but with more data added).

Redo Writes/sec

Redo Writes/sec is the rate at which pages are being written to the transaction (redo) log.

Relocatable Heap Pages

Relocatable Heap Pages is the number of pages used for relocatable heaps (cursors, statements, procedures, triggers, views, etc.).

Remoteput Wait/sec

Remoteput Wait/sec is the rate at which the communication link must wait because it does not have buffers available to send information. This statistic is collected for NetBIOS (both sessions and datagrams) and IPX protocols only.

Requests/sec

Requests/sec is the rate at which the engine is being entered to allow it to handle a new request or continue processing an existing request.

Rereads Queued/sec

A reread occurs when a read request for a page is received by the database IO subsystem while an asynchronous read IO operation has been posted to the operating system but has not completed. Rereads Queued/sec is the rate at which this condition is occurring.

Rereceived Packets/sec

Rereceived Packets/sec is the rate at which duplicate network packets are being received.

Retransmitted Packets/sec

Retransmitted Packets/sec is the rate at which network packets are being retransmitted.

Rollback Log Pages

Rollback Log Pages is the number of pages in the rollback log.

Rollback/sec

Rollback/sec is the rate at which Rollback requests are being handled.

Adaptive Server Anywhere

The Adaptive Server Anywhere object provides information about the database server.

Sends Failed/sec

Sends Failed/sec is the rate at which the underlying protocol(s) failed to send a packet.

Statement

Statement is the number of prepared statements that are currently being maintained by the engine.

TotalBuffers

TotalBuffers number of network buffers.

Trigger Pages

Trigger Pages is the number of relocatable heap pages used for triggers.

Unscheduled requests

Unscheduled requests is the number of requests that are currently queued up waiting for an available engine thread.

View Pages

View Pages is the number of relocatable heap pages used for views.

Voluntary blocks/sec

Voluntary blocks/sec is the rate at which engine threads voluntarily block on pending disk IO.

Waitread Full Compare/sec

Waitread Full Compare/sec is the rate at which read requests associated with a full comparison (a comparison beyond the hash value in an index) must be satisfied by a synchronous read operation.

Waitread Optimizer/sec

Waitread Optimizer/sec is the rate at which read requests posted by the optimizer must be satisfied by a synchronous read operation.

Waitread Other/sec

Waitread Other/sec is the rate at which read requests from other sources must be satisfied by a synchronous read operation.

Waitread SysConnection/sec

Waitread SysConnection/sec is the rate at which read requests posted from the system connection must be satisfied by a synchronous read operation. The system connection is a special connection that is used as the context before a connection is made and for operations performed outside of a client connection.

Waitread Temporary Table/sec

Waitread Temporary Table/sec is the rate at which read requests for a temporary table must be satisfied by a synchronous read operation.

Statistic	Description
Active Requests	Active Requests is the number of engine threads that are currently handling a request.
Asynchronous Reads/sec	Asynchronous Reads/sec is the rate at which pages are being read asynchronously from disk.
Asynchronous Writes/sec	Asynchronous Writes/sec is the rate at which pages are being written asynchronously to disk.
Bytes Received/sec	Bytes Received/sec is the rate at which network data (in bytes) are being received.
Bytes Transmitted/sec	Bytes Transmitted/sec is the rate at which bytes are being transmitted over the network.
Cache Hits/sec	Cache Hits/sec is the rate at which database page lookups are satisfied by finding the page in the cache.
Cache Index Internal Reads/sec	Cache Index Internal Reads/sec is the rate at which index internal-node pages are being read from the cache.
Cache Index Leaf Reads/sec	Cache Index Leaf Reads/sec is the rate at which index leaf pages are being read from the cache.
Cache Reads/sec	Cache Reads/sec is the rate at which database pages are being looked up in the cache.
Cache Table Reads/sec	Cache Table Reads/sec is the rate at which table pages are being read from the cache.
Cache Writes/sec	Cache Writes/sec is the rate at which pages in the cache are being modified (in pages/sec).
Checkpoint Flushes/sec	Checkpoint Flushes/sec is the rate at which ranges of adjacent pages are being written out during a checkpoint.
Checkpoint Log/sec	Checkpoint Log/sec is the rate at which the transaction log is being checkpointed.
Checkpoint Urgency	Checkpoint Urgency is expressed as a percentage.
Checkpoints/sec	Checkpoints/sec is the rate at which checkpoints are being performed.
Commit files/sec	Commit files/sec is the rate at which the engine is forcing a flush of the disk cache. On Windows NT and NetWare platforms, the disk cache does not need to be flushed because unbuffered (direct) I/O is used.
Commits/sec	Commits/sec is the rate at which Commit requests are being handled.
Context Switch Checks/sec	Context Switch Checks/sec is the rate at which the current engine thread is volunteering to give up the CPU to another engine thread.
Context Switches/sec	Context Switches/sec is the rate at which the current engine thread is being changed.
Continue Requests/sec	Continue Requests/sec is the rate at which "CONTINUE" requests are being issued to the engine.
Corrupt Packets/sec	Corrupt Packets/sec is the rate at which corrupt network packets are being received.
Current IO	Current IO is the current number of file I/Os issued by the engine which have not yet completed.
Current Reads	Current Reads is the current number of file reads issued by the engine which have not yet completed.
Current Writes	Current Writes is the current number of file writes issued by the engine which have not yet completed.
Cursor	Cursor is the number of declared cursors that are currently being maintained by the engine.
Dirty Pages	Dirty Pages is the number of pages in the cache which must be written out and which do not belong to temporary files.
Disk Index Internal Reads/sec	Disk Index Internal Reads/sec is the rate at which index internal-node pages are being read from disk.
Disk Index Leaf Reads/sec	Disk Index Leaf Reads/sec is the rate at which index leaf pages are being read from disk.
Disk Reads/sec	Disk Reads/sec is the rate at which pages are being read from file.
Disk SyncReads/sec	Disk SyncReads/sec is the rate at which pages are being read synchronously from disk.
Disk SyncWrite Other/sec	Disk SyncWrite Other/sec is the rate at which pages are being written synchronously to disk for a reason not covered by other "Disk SyncWrites _____/sec" counters.
Disk SyncWrites Checkpoint/sec	Disk SyncWrites Checkpoint/sec is the rate at which pages are being written synchronously to disk for a checkpoint.
Disk SyncWrites Extend/sec	Disk SyncWrites Extend/sec is the rate at which pages are being written synchronously to disk while extending a database file.
Disk SyncWrites Free Current/sec	Disk SyncWrites Free Current/sec is the rate at which pages are being written synchronously to disk to free a page that cannot remain in the in-memory free list.
Disk SyncWrites Free Push/sec	Disk SyncWrites Free Push/sec is the rate at which pages are being written synchronously to disk to free a page that can remain in the in-memory free list.
Disk SyncWrites Log/sec	Disk SyncWrites Log/sec is the rate at which pages are being written synchronously to the transaction log.
Disk SyncWrites Rollback/sec	Disk SyncWrites Rollback/sec is the rate at which pages are being written synchronously to the rollback log.
Disk SyncWrites/sec	Disk SyncWrites/sec is the rate at which pages are being written synchronously to disk. It is the sum of all the other "Disk SyncWrites _____/sec" counters.
Disk Table Reads/sec	Disk Table Reads/sec is the rate at which table pages are being read from disk.
Disk Waitreads/sec	Disk Waitreads/sec is the rate at which the engine is waiting synchronously for the completion of a read IO operation which was originally issued as an asynchronous read. Waitreads often occur due to cache misses on systems that support asynchronous IO.
Disk Waitwrites/sec	Disk Waitwrites/sec is the rate at which the engine is waiting synchronously for the completion of a write IO operation which was originally issued as an asynchronous write.
Disk Writes/sec	Disk Writes/sec is the rate at which modified pages are being written to disk.
Dropped Packets/sec	Dropped Packets/sec is the rate at which network packets are being dropped due to lack of buffer space.
Extend Database/sec	Extend Database/sec is the rate (in pages/sec) at which the database file is being extended.
Extend Temporary File/sec	Extend Temporary File/sec is the rate (in pages/sec) at which temporary files are being extended.
Free Buffers	Number of free network buffers.
Freelist Write Current/sec	Freelist Write Current/sec is the rate at which pages that cannot remain in the in-memory free list are being freed.
Freelist Write Push/sec	Freelist Write Push/sec is the rate at which pages that can remain in the in-memory free list are being freed.
Full compares/sec	Full compares/sec is the rate at which comparisons beyond the hash value in an index must be performed.
IO to Recover	IO to Recover is the estimated number of IO operations required to recover the database.
Idle Active/sec	Idle Active/sec is the rate at which the engine's idle thread becomes active to do idle writes, idle checkpoints, etc.
Idle Checkpoints/sec	Idle Checkpoints/sec is the rate at which checkpoints are completed by the engine's idle thread. An idle checkpoint occurs whenever the idle thread writes out the last dirty page in the cache.
Idle Waits/sec	Idle Waits/sec is the number of times per second that the server goes idle waiting for IO completion or a new request.
Idle Writes/sec	Idle Writes/sec is the rate at which disk writes are being issued by the engine's idle thread.
Index Fills	Index Fills is the number of times a new temporary merge index is created.
Index Merges	Index Merges is the number of times a temp index has been merged into a main index
Index adds/sec	Index adds/sec is the rate at which entries are being added to indexes.
Index lookups/sec	Index lookups/sec is the rate at which entries are being looked up in indexes.
Lock Table Pages	Lock Table Pages is the number of pages used to store lock information.
Main Heap Pages	Main Heap Pages is the number of pages used for global engine data structures.
Map Pages	Map Pages is the number of map pages used for accessing the lock table, frequency table, and table layout.
Maximum IO	Maximum IO is the maximum value that "Current IO" has reached.
Maximum Reads	Maximum Reads is the maximum value that "Current Reads" has reached.
Maximum Writes	Maximum Writes is the maximum value that "Current Writes" has reached.
Multi-packets Received/sec	Multi-packets Received/sec is the rate at which multi-packet deliveries are being received.
Multi-packets Transmitted/sec	Multi-packets Transmitted/sec is the rate at which multi-packet deliveries are being transmitted.
Open cursors	Open cursors is the number of open cursors that are currently being maintained by the engine.
Packets Received/sec	Packets Received/sec is the rate at which network packets are being received.
Packets Transmitted/sec	Packets Transmitted/sec is the rate at which network packets are being transmitted.
Page Relocations/sec	Page Relocations/sec is the rate at which relocatable heap pages are being read from the temporary file.
Pending requests/sec	Pending requests/sec is the rate at which the engine is detecting the arrival of new requests.
Ping1/sec	Ping1/sec is the rate at which ping requests which go all the way down into the engine are serviced.
Ping2/sec	Ping2/sec is the rate at which ping requests which are turned around at the top of the protocol stack are serviced.
Procedure Pages	Procedure Pages is the number of relocatable heap pages used for procedures.
Read Hints Used/sec	Read Hints Used/sec is the rate at which page-read operations are being satisfied immediately from cache thanks to an earlier read hint.
Read Hints/sec	A read hint is an asynchronous read operation for a page that the server is likely to need soon. Read Hints/sec is the rate at which such read operations are being issued.
Recovery Urgency	Recovery Urgency is expressed as a percentage.
Redo Free Commits/sec	A "Redo Free Commit" occurs when a commit of the transaction (redo) log is requested but the log has already been written (so the commit was done for "free").
Redo Rewrites/sec	Redo Rewrites/sec is the rate at which pages that were previously written to the transaction log (but were not full) are being written to the transaction log again (but with more data added).
Redo Writes/sec	Redo Writes/sec is the rate at which pages are being written to the transaction (redo) log.
Relocatable Heap Pages	Relocatable Heap Pages is the number of pages used for relocatable heaps (cursors, statements, procedures, triggers, views, etc.).
Remoteput Wait/sec	Remoteput Wait/sec is the rate at which the communication link must wait because it does not have buffers available to send information. This statistic is collected for NetBIOS (both sessions and datagrams) and IPX protocols only.
Requests/sec	Requests/sec is the rate at which the engine is being entered to allow it to handle a new request or continue processing an existing request.
Rereads Queued/sec	A reread occurs when a read request for a page is received by the database IO subsystem while an asynchronous read IO operation has been posted to the operating system but has not completed. Rereads Queued/sec is the rate at which this condition is occurring.
Rereceived Packets/sec	Rereceived Packets/sec is the rate at which duplicate network packets are being received.
Retransmitted Packets/sec	Retransmitted Packets/sec is the rate at which network packets are being retransmitted.
Rollback Log Pages	Rollback Log Pages is the number of pages in the rollback log.
Rollback/sec	Rollback/sec is the rate at which Rollback requests are being handled.
Adaptive Server Anywhere	The Adaptive Server Anywhere object provides information about the database server.
Sends Failed/sec	Sends Failed/sec is the rate at which the underlying protocol(s) failed to send a packet.
Statement	Statement is the number of prepared statements that are currently being maintained by the engine.
TotalBuffers	TotalBuffers number of network buffers.
Trigger Pages	Trigger Pages is the number of relocatable heap pages used for triggers.
Unscheduled requests	Unscheduled requests is the number of requests that are currently queued up waiting for an available engine thread.
View Pages	View Pages is the number of relocatable heap pages used for views.
Voluntary blocks/sec	Voluntary blocks/sec is the rate at which engine threads voluntarily block on pending disk IO.
Waitread Full Compare/sec	Waitread Full Compare/sec is the rate at which read requests associated with a full comparison (a comparison beyond the hash value in an index) must be satisfied by a synchronous read operation.
Waitread Optimizer/sec	Waitread Optimizer/sec is the rate at which read requests posted by the optimizer must be satisfied by a synchronous read operation.
Waitread Other/sec	Waitread Other/sec is the rate at which read requests from other sources must be satisfied by a synchronous read operation.
Waitread SysConnection/sec	Waitread SysConnection/sec is the rate at which read requests posted from the system connection must be satisfied by a synchronous read operation. The system connection is a special connection that is used as the context before a connection is made and for operations performed outside of a client connection.
Waitread Temporary Table/sec	Waitread Temporary Table/sec is the rate at which read requests for a temporary table must be satisfied by a synchronous read operation.