Hi Hackers, I found that bgwriter increments usage count of buffers when it writes the buffers. I feel this behavior is strange, because the behavior of bgwriter will affect buffer management strategy. When backends write LRU dirty buffers, they are replaced immediately. However, when bgwriter writes dirty buffer, the replacement is postponed until the next rotation of CLOCK.
If the behavior is not intended, another UnpinBuffer that doesn't increase the buffers usage count will be needed. Otherwise, bgwriter should do behavior that looks like VACUUM, using StrategyHintVacuum(true). I'll appreciate any comments. Thanks, --- ITAGAKI Takahiro NTT Cyber Space Laboratories ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match