probes --- the BUFFER_READ_DONE probe provides the same information and more
besides. Expand the LOCK_WAIT_START/DONE probe arguments so that there's
actually some chance of telling what is being waited for. Update and
clean up the documentation.
<entry>Probe that fires when a checkpoint is performed. arg0 holds the bitwise flags used to distinguish different checkpoints such as shutdown, immediate or force.</entry>
<entry>Probe that fires when a checkpoint is started.
arg0 holds the bitwise flags used to distinguish different checkpoint
types, such as shutdown, immediate or force.</entry>
</row>
<row>
<entry>checkpoint-done</entry>
<entry>(int, int, int, int, int)</entry>
<entry>Probe that fires when a checkpoint is complete. arg0 is the number of buffers written. arg1 is the total number of buffers. arg2, arg3 and arg4 contain the number of xlog file(s) added, removed and recycled respectively.</entry>
<entry>Probe that fires when a checkpoint is complete.
(The probes listed next fire in sequence during checkpoint processing.)
arg0 is the number of buffers written. arg1 is the total number of
buffers. arg2, arg3 and arg4 contain the number of xlog file(s) added,
removed and recycled respectively.</entry>
</row>
<row>
<entry>clog-checkpoint-start</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the CLOG portion of the checkpoint is started. arg0 is either true or false, true for normal checkpoint, false for postmaster shutdown.</entry>
<entry>Probe that fires when the CLOG portion of a checkpoint is started.
arg0 is true for normal checkpoint, false for shutdown
checkpoint.</entry>
</row>
<row>
<entry>clog-checkpoint-done</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the CLOG portion of the checkpoint is complete. arg0 has the same meaning as clog-checkpoint-start.</entry>
<entry>Probe that fires when the CLOG portion of a checkpoint is
complete. arg0 has the same meaning as for clog-checkpoint-start.</entry>
</row>
<row>
<entry>subtrans-checkpoint-start</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the SUBTRANS portion of the checkpoint is started. arg0 is either true or false, true for normal checkpoint, false for postmaster shutdown.</entry>
<entry>Probe that fires when the SUBTRANS portion of a checkpoint is
started.
arg0 is true for normal checkpoint, false for shutdown
checkpoint.</entry>
</row>
<row>
<entry>subtrans-checkpoint-done</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the SUBTRANS portion of the checkpoint is complete. arg0 has the same meaning as subtrans-checkpoint-done.</entry>
<entry>Probe that fires when the SUBTRANS portion of a checkpoint is
complete. arg0 has the same meaning as for
subtrans-checkpoint-start.</entry>
</row>
<row>
<entry>multixact-checkpoint-start</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the MultiXact portion of the checkpoint is started. arg0 is either true or false, true for normal checkpoint, false for postmaster shutdown.</entry>
<entry>Probe that fires when the MultiXact portion of a checkpoint is
started.
arg0 is true for normal checkpoint, false for shutdown
checkpoint.</entry>
</row>
<row>
<entry>multixact-checkpoint-done</entry>
<entry>(bool)</entry>
<entry>Probe that fires when the MultiXact portion of the checkpoint is complete. arg0 has the same meaning as multixact-checkpoint-start.</entry>
<entry>Probe that fires when the MultiXact portion of a checkpoint is
complete. arg0 has the same meaning as for
multixact-checkpoint-start.</entry>
</row>
<row>
<entry>buffer-checkpoint-start</entry>
<entry>(int)</entry>
<entry>Probe that fires when the shared buffers portion of the checkpoint is started to flush out the buffers, and it's always followed by buffer-sync-start. arg0 holds the bitwise flags used to distinguish different checkpoints such as shutdown, immediate or force</entry>
<entry>Probe that fires when the buffer-writing portion of a checkpoint
is started.
arg0 holds the bitwise flags used to distinguish different checkpoint
types, such as shutdown, immediate or force.</entry>
</row>
<row>
<entry>buffer-sync-start</entry>
<entry>(int, int)</entry>
<entry>Probe that fires when we begin to write dirty buffers during
checkpoint (after identifying which buffers must be written).
arg0 is the total number of buffers.
arg1 is the number that are currently dirty and need to be written.</entry>
</row>
<row>
<entry>buffer-sync-written</entry>
<entry>(int)</entry>
<entry>Probe that fires after each buffer is written during checkpoint.
arg0 is the ID number of the buffer.</entry>
</row>
<row>
<entry>buffer-sync-done</entry>
<entry>(int, int, int)</entry>
<entry>Probe that fires when all dirty buffers have been written.
arg0 is the total number of buffers.
arg1 is the number of buffers actually written by the checkpoint process.
arg2 is the number that were expected to be written (arg1 of
buffer-sync-start); any difference reflects other processes flushing
buffers during the checkpoint.</entry>
</row>
<row>
<entry>buffer-checkpoint-sync-start</entry>
<entry>()</entry>
<entry>Probe that fires to fsync buffers to disk, and it's always preceeded by buffer-checkpoint-start, buffer-sync-start, and buffer-flush-start. The time difference between buffer-checkpoint-start and buffer-checkpoint-sync-start is the write time, and the difference between buffer-checkpoint-sync-start and buffer-checkpoint-done is the sync time.</entry>
<entry>Probe that fires after dirty buffers have been written to the
kernel, and before starting to issue fsync requests.</entry>
</row>
<row>
<entry>buffer-checkpoint-done</entry>
<entry>()</entry>
<entry>Probe that fires when the shared buffers portion of the checkpoint is complete. This probe is fired after buffer-checkpoint-sync-start.</entry>
<entry>Probe that fires when syncing of buffers to disk is
complete.</entry>
</row>
<row>
<entry>twophase-checkpoint-start</entry>
<entry>()</entry>
<entry>Probe that fires when the two-phase portion of the checkpoint is started.</entry>
<entry>Probe that fires when the two-phase portion of a checkpoint is
started.</entry>
</row>
<row>
<entry>twophase-checkpoint-done</entry>
<entry>()</entry>
<entry>Probe that fires when the two-phase portion of the checkpoint is complete.</entry>
</row>
<row>
<entry>buffer-hit</entry>
<entry>(bool)</entry>
<entry>Probe that fires when a read request is satisfied from the buffer cache. arg0 is either true or false, true for local buffer, false for shared buffer.</entry>
</row>
<row>
<entry>buffer-miss</entry>
<entry>(bool)</entry>
<entry>Probe that fires when a read request requires disk access. arg0 is either true or false, true for local buffer, false for shared buffer .</entry>
<entry>Probe that fires when the two-phase portion of a checkpoint is
<entry>Probe that fires when a buffer read is started. arg0 and arg1 contain the fork and block numbers. arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs respectively. arg5 is either true or false, true for local buffer, false for shared buffer.</entry>
<entry>Probe that fires when a buffer read is complete. arg0 and arg1 contain the fork and block numbers. arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs respectively. arg5 is either true or false, true for local buffer, false for shared buffer. arg6 is true if buffer is found in the pool, false otherwise.</entry>
</row>
<row>
<entry>buffer-sync-start</entry>
<entry>(int, int)</entry>
<entry>Probe that fires to write out all dirty buffers in the pool at checkpoint time, and it's always preceeded by buffer-checkpoint-start and followed by buffer-flush-start. arg0 is the total number of buffers. arg1 is the number it intends to write.</entry>
</row>
<row>
<entry>buffer-sync-done</entry>
<entry>(int, int, int)</entry>
<entry>Probe that fires when all dirty buffers have been written. arg0 is the total number of buffers. arg1 is the number actually written. arg2 is the total number to write.</entry>
<entry>Probe that fires when a buffer read is started.
arg0 and arg1 contain the fork and block numbers of the page (but
arg1 will be -1 if this is a relation extension request).
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
identifying the relation.
arg5 is true for a local buffer, false for a shared buffer.
arg6 is true for a relation extension request, false for normal
read.</entry>
</row>
<row>
<entry>buffer-sync-written</entry>
<entry>(int)</entry>
<entry>Probe that fires when the buffer pool syncing is in progress (e.g. buffer-sync-start has fired) and a buffer has been successfully written.</entry>
<entry>Probe that fires when a buffer read is complete.
arg0 and arg1 contain the fork and block numbers of the page (if this
is a relation extension request, arg1 now contains the block number
of the newly added block).
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
identifying the relation.
arg5 is true for a local buffer, false for a shared buffer.
arg6 is true for a relation extension request, false for normal
read.
arg7 is true if the buffer was found in the pool, false if not.</entry>
</row>
<row>
<entry>buffer-flush-start</entry>
<entry>(Oid, Oid, Oid)</entry>
<entry>Probe that fires when a shared buffer needs to be physically written out to disk, and it's always preceeded by buffer-sync-start. This actually just passes the buffer contents to the kernel; the real write to disk happens later by the kernel. This is okay since the changes have already been written to the WAL. arg0, arg1, and arg2 contain the tablespace, database, and relation OIDs respectively.</entry>
<entry>Probe that fires before issuing any write request for a shared
buffer.
arg0 and arg1 contain the fork and block numbers of the page.
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
identifying the relation.</entry>
</row>
<row>
<entry>buffer-flush-done</entry>
<entry>(Oid, Oid, Oid)</entry>
<entry>Probe that fires when the buffer flush is complete, and it's always followed by buffer-checkpoint-sync-start. arg0, arg1, and arg2 have the same meaning as buffer-flush-start.</entry>
<entry>Probe that fires when the server starts writting out dirty buffers, indicating that the bgwriter is ineffective or shared_buffers is too small. arg0 refers to a fork in a relation. arg1 is the disk block number. arg2, arg3, arg4 contain the tablespace, database, and relation OIDs respectively.</entry>
<entry>Probe that fires when a server process begins to write a dirty
buffer. (If this happens often, it implies that
<xref linkend="guc-shared-buffers"> is too
small or the bgwriter control parameters need adjustment.)
arg0 and arg1 contain the fork and block numbers of the page.
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
<entry>Probe that fires when the buffer write is complete. The arguments are the same as buffer-write-dirty-start probe.</entry>
<entry>Probe that fires when a dirty-buffer write is complete.
The arguments are the same as for buffer-write-dirty-start.</entry>
</row>
<row>
<entry>wal-buffer-write-dirty-start</entry>
<entry>()</entry>
<entry>Probe that fires when the server starts writting out dirty WAL buffers, indicating that no more WAL buffer pages are available. Increasing wal_buffers will reduce the writes and may improve performance.</entry>
<entry>Probe that fires when when a server process begins to write a
dirty WAL buffer because no more WAL buffer space is available.
(If this happens often, it implies that
<xref linkend="guc-wal-buffers"> is too small.)</entry>
</row>
<row>
<entry>wal-buffer-write-dirty-done</entry>
<entry>()</entry>
<entry>Probe that fires when the WAL buffer write is complete.</entry>
<entry>Probe that fires when a dirty WAL buffer write is complete.</entry>
</row>
<row>
<entry>xlog-insert</entry>
<entry>(unsigned char, unsigned char)</entry>
<entry>Probe that fires when data is inserted in the XLog. arg0 is the resource manager (rmid) for the record. arg1 represents the info flags.</entry>
<entry>Probe that fires when a WAL record is inserted.
arg0 is the resource manager (rmid) for the record.
arg1 contains the info flags.</entry>
</row>
<row>
<entry>xlog-switch</entry>
<entry>()</entry>
<entry>Probe that fires when an XLog switch is requested. This is always immediately preceeded by an firing of the xlog-insert probe.</entry>
</row>
<row>
<entry>sort-start</entry>
<entry>(int, bool, int, int, bool)</entry>
<entry>Probe that fires when sort is performed. arg0 indicates heap, index or datum sort. arg1 is true for unique enforcement. arg2 is the number of keys. arg3 represents workMem. arg3 is true for random access.</entry>
</row>
<row>
<entry>sort-done</entry>
<entry>(unsigned long, long)</entry>
<entry>Probe that fires when sort is complete. arg0 is either true or false, true for external sort, false for internal sort. arg1 is the number of disk blocks used for external sort or memory used in KB for internal sort.</entry>
<entry>Probe that fires when a WAL segment switch is requested.</entry>
<entry>Probes that fires when reading a block from a relation. arg0 and arg1 contain fork and block number. arg2, arg3 and arg4 contain the tablespace, database and relation OIDs.</entry>
<entry>Probe that fires when beginning to read a block from a relation.
arg0 and arg1 contain the fork and block numbers of the page.
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
<entry>Probes that fires when a block read is complete. arg0 and arg1 contan fork and block number. arg2, arg3, arg4 contain the tablespace, database, and relation OIDs. arg5 is the path to the relation's file. arg6 is the number of bytes read. arg7 is the block size.</entry>
<entry>Probes that fires when writing a block to the appropriate relation. arg0 and arg1 contain fork and block number. arg2, arg3 and arg4 contain the tablespace, database and relation OIDs.</entry>
<entry>Probe that fires when beginning to write a block to a relation.
arg0 and arg1 contain the fork and block numbers of the page.
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
<entry>Probes that fires when a block write is complete. arg0 and arg1 contan fork and block number. arg2, arg3, arg4 contain the tablespace, database, and relation OIDs. arg5 is the path to the relation's file. arg6 is number of bytes read. arg7 is the block size.</entry>
<entry>Probe that fires when a block write is complete.
arg0 and arg1 contain the fork and block numbers of the page.
arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
identifying the relation.
arg5 is the number of bytes actually written, while arg6 is the number
requested (if these are different it indicates trouble).</entry>
</row>
<row>
<entry>deadlock-found</entry>
<entry>()</entry>
<entry>Probe that fires when a deadlock is found by the deadlock detector.</entry>
<entry>sort-start</entry>
<entry>(int, bool, int, int, bool)</entry>
<entry>Probe that fires when a sort operation is started.
arg0 indicates heap, index or datum sort.
arg1 is true for unique-value enforcement.
arg2 is the number of key columns.
arg3 is the number of kilobytes of work memory allowed.
arg4 is true if random access to the sort result is required.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="dev-trace-point-table">
<title>Built-in Probes for Developers</title>
<tgroup cols="3">
<thead>
<row>
<entry>Name</entry>
<entry>Parameters</entry>
<entry>Description</entry>
<entry>sort-done</entry>
<entry>(bool, long)</entry>
<entry>Probe that fires when a sort is complete.
arg0 is true for external sort, false for internal sort.
arg1 is the number of disk blocks used for an external sort,
or kilobytes of memory used for an internal sort.</entry>
</row>
</thead>
<tbody>
<row>
<entry>lwlock-acquire</entry>
<entry>(LWLockId, LWLockMode)</entry>
<entry>Probe that fires when an LWLock has been acquired. arg0 is a predefined or dynamic ID defined in LWLockId enum. arg1 is a lock mode, either exclusive or shared.</entry>
<entry>Probe that fires when an LWLock has been acquired.
arg0 is the LWLock's ID.
arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry>lwlock-release</entry>
<entry>(LWLockId)</entry>
<entry>Probe that fires when an LWLock has been released. arg0 is a predefined or dynamic ID defined in LWLockId enum.</entry>
<entry>Probe that fires when an LWLock has been released (but note
that any released waiters have not yet been awakened).
arg0 is the LWLock's ID.</entry>
</row>
<row>
<entry>lwlock-wait-start</entry>
<entry>(LWLockId, LWLockMode)</entry>
<entry>Probe that fires when an LWLock was not immediately available and a backend has begun to wait for the lock to become available. arg0 is a predefined or dynamic ID defined in LWLockId enum. arg1 is a lock mode, either exclusive or shared .</entry>
</row>
<entry>Probe that fires when an LWLock was not immediately available and
a server process has begun to wait for the lock to become available.
arg0 is the LWLock's ID.
arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry>lwlock-wait-done</entry>
<entry>(LWLockId, LWLockMode)</entry>
<entry>Probe that fires when a backend has been released from its wait for an LWLock. arg0 is a predefined or dynamic ID defined in LWLockId enum. arg1 is a lock mode, either exclusive or shared.</entry>
<entry>Probe that fires when a server process has been released from its
wait for an LWLock (it does not actually have the lock yet).
arg0 is the LWLock's ID.
arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry>lwlock-condacquire</entry>
<entry>(LWLockId, LWLockMode)</entry>
<entry>Probe that fires when an LWLock was successfully acquired when the caller specified no waiting. arg0 is a predefined or dynamic ID defined in LWLockId enum. arg1 is a lock mode, either exclusive or shared.</entry>
</row>
<entry>Probe that fires when an LWLock was successfully acquired when the
caller specified no waiting.
arg0 is the LWLock's ID.
arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry>lwlock-condacquire-fail</entry>
<entry>(LWLockId, LWLockMode)</entry>
<entry>Probe that fires when an LWLock was not successfully acquired when the caller specified no waiting. arg0 is a predefined or dynamic ID defined in LWLockId enum. arg1 is a lock mode, either exclusive or shared.</entry>
<entry>Probe that fires when an LWLock was not successfully acquired when
the caller specified no waiting.
arg0 is the LWLock's ID.
arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry>lock-wait-start</entry>
<entry>(unsigned int, LOCKMODE)</entry>
<entry>Probe that fires when a request for a heavyweight lock (lmgr lock) has begun to wait because the lock is not available. arg0 is the unique ID tag defined in LOCKTAG struct. arg1 is an integer indicating a lock type.
<entry>Probe that fires when a request for a heavyweight lock (lmgr lock)
has begun to wait because the lock is not available.
arg0 through arg3 are the tag fields identifying the object being
locked. arg4 indicates the type of object being locked.
arg5 indicates the lock type being requested.</entry>
</row>
<row>
<entry>lock-wait-done</entry>
<entry>(unsigned int, LOCKMODE)</entry>
<entry>Probe that fires when a request for a heavyweight lock (lmgr lock) has finished waiting (i.e., has acquired the lock). arg0 is the unique ID tag defined in LOCKTAG struct. arg1 is an integer indicating a lock type.
Tom Lane
17 years ago