Hi, i went across a checkpoint problematic (90% load, near real time app). I've read in pg-documentation what exists about CHECKPOINT and the configuration parameters. But there're still many open questions as: What actually happens if a checkpoint occours? OK, all dirty pages of data files get written to disk...but Are read requests (simple selects) still possible and quickly answered? What happens to wite-operations? Do they get queued or can they be written to xlog while the fsync is running? Is it maybe really the case but wave of pending statements arises from the reduced i/o capacity which is left due to the fsync? How about increasing the interval more and more? Will this produce more and more dirty pages or is it just that a possible restart will take a longer time since the xlog is longer? Questions over questions. Can you please give me a clearing little insight.
