New DTrace Probes in PostgreSQL 8.4

DTrace probes were introduced in PostgreSQL starting in 8.2. Initially, only a handful were added, and they were mostly for developers. In 8.4, many more (46 to be exact) have been added, and they are targeted more toward database administrators as shown below.

query-parse-start(const char \*)
query-parse-done(const char \*)
query-rewrite-start(const char \*)
query-rewrite-done(const char \*)
query-plan-start()
query-plan-done()
query-execute-start()
query-execute-done()
query-start(const char \*)
query-done(const char \*)
statement-status(const char \*)
sort-start(int, bool, int, int, bool)
sort-done(unsigned long, long)
buffer-read-start(ForkNumber, BlockNumber, Oid, Oid, Oid, bool)
buffer-read-done(ForkNumber, BlockNumber, Oid, Oid, Oid, bool, bool)buffer-flush-start(Oid, Oid, Oid)
buffer-flush-done(Oid, Oid, Oid)
buffer-hit(bool)buffer-miss(bool)
buffer-checkpoint-start(int)
buffer-checkpoint-sync-start()
buffer-checkpoint-done()
buffer-sync-start(int, int)
buffer-sync-written(int)
buffer-sync-done(int, int, int)
buffer-write-dirty-start(ForkNumber, BlockNumber, Oid, Oid, Oid)
buffer-write-dirty-done(ForkNumber, BlockNumber, Oid, Oid, Oid)
deadlock-found()
checkpoint-start(int)
checkpoint-done(int, int, int, int, int)
clog-checkpoint-start(bool)
clog-checkpoint-done(bool)
subtrans-checkpoint-start(bool)
subtrans-checkpoint-done(bool)
multixact-checkpoint-start(bool)
multixact-checkpoint-done(bool)
twophase-checkpoint-start()
twophase-checkpoint-done()
smgr-md-read-start(ForkNumber, BlockNumber, Oid, Oid, Oid)
smgr-md-read-done(ForkNumber, BlockNumber, Oid, Oid, Oid, const char \*, int, int)
smgr-md-write-start(ForkNumber, BlockNumber, Oid, Oid, Oid)
smgr-md-write-done(ForkNumber, BlockNumber, Oid, Oid, Oid, const char \*, int, int)
xlog-insert(unsigned char, unsigned char)
xlog-switch()
wal-buffer-write-dirty-start()
wal-buffer-write-dirty-done()

Documentation should be available in 8.4 doc page soon, but if you don't want to wait, check out the doc patch I recently submitted. If you're using or plan to use the probes, I'd love to hear your feedback, both positive and constructive!

Special thanks to Theo Schlossnagle, Robert Treat, Zdenek Kotala, Alvaro Herrera and Simon Riggs for their contributions with the probes as well as reviewing them.

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