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[Solved] Struggling with concept of WAL files

3 Posts
2 Users
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Posts: 17
Active Member
Topic starter

Hi guys,

Im struggling with write ahead logs and understanding them. I get the concept that it is basically a role back journal in reverse and any data, say web history for example, is written to the log and then committed to the actual database at a checkpoint thats either automatic at 1000 pages or forced by design. Am I correct in saying this is to save multiple writes to disk? But, if this log is written to disk how are we saving on writes? If the file is held in memory then this would make more sense to me but I cant find much detail around this.

I appreciate its highly likely I am missing a very simple concept here so I apologise upfront.



Posted : 02/12/2020 10:17 am
Posts: 481
Honorable Member

I recently did a bit of a write-up on WAL files:

Might be useful to you, it does explain about them outside of using them for timelining

Posted : 02/12/2020 3:34 pm
trewmte reacted
Posts: 17
Active Member
Topic starter

Thanks minime2k9, very in depth explanation. I scanned through it but to be honest beed to take some time to read it in detail and come back to you.

Thanks again.

Posted : 02/12/2020 8:11 pm