Re: WAL cleanup
Ok thanks, just more query. "If all 10 segments are filled, then it will be expected (wait) for the first of the segments to go to the archive." Does it mean application writes will wait until one of the wal segment is made free(that means atleast checkpoint must complete so segment file can move to wal archive) ? On Fri, 22 Apr 2022, 18:06 ткаленко кирилл, wrote: > Set the maximum to 50% of the estimated value. If it is possible to use 60 > GB for the archive, set it to 30 GB. >
Re: WAL cleanup
Sorry for typo in last thread point 5, I meant to type "the ones which moves segments from WAL to WAL Archive" On Fri, 22 Apr 2022, 17:13 Surinder Mehra, wrote: > Ok thanks for clarifying. O have follow up queries > 1. Wal has only 10 segments and default checkpoint frequency is 3 minutes > What if application writes fill up all 10 segments before next checkpoint > interval, would it trigger another checkpoint followed by moving of segments > > 2. Does it always move segments to archive after checkpoint? What if > checkpoint is taking time and no space left in WAL. i.e. wal reached its > max size(10*segmentsize) > > 3. If point 2 is true, why do we need walarchive. Since data has been > flushed to disk with checkpoint. And any data not checkpointed is present > in WAL, why do we need archive directory. > > 4. I have seen WAL size fixed(10G with segment size as 1G) to max size and > WAL archive increases to 60GB. Does it mean cleaner thread wasn't frequent > enough? > 5. Are cleaner threads and the ones which love segments have any relation > to checkpoint process or performance impact. If so, are they tunable by > user ? > > > On Fri, 22 Apr 2022, 16:52 ткаленко кирилл, wrote: > >> Cleaning takes place in a separate thread. >> Transfer of segments occurs in a separate thread after the checkpoint. >> >>
Re: WAL cleanup
Ok thanks for clarifying. O have follow up queries 1. Wal has only 10 segments and default checkpoint frequency is 3 minutes What if application writes fill up all 10 segments before next checkpoint interval, would it trigger another checkpoint followed by moving of segments 2. Does it always move segments to archive after checkpoint? What if checkpoint is taking time and no space left in WAL. i.e. wal reached its max size(10*segmentsize) 3. If point 2 is true, why do we need walarchive. Since data has been flushed to disk with checkpoint. And any data not checkpointed is present in WAL, why do we need archive directory. 4. I have seen WAL size fixed(10G with segment size as 1G) to max size and WAL archive increases to 60GB. Does it mean cleaner thread wasn't frequent enough? 5. Are cleaner threads and the ones which love segments have any relation to checkpoint process or performance impact. If so, are they tunable by user ? On Fri, 22 Apr 2022, 16:52 ткаленко кирилл, wrote: > Cleaning takes place in a separate thread. > Transfer of segments occurs in a separate thread after the checkpoint. > >
