Greetings, * Ravi Krishna (srkrishna1@xxxxxxx) wrote: > > There is no such thing as a "read only" table in PostgreSQL. All tables are read/write no matter that frequency of either event. There is nothing > inherently special about "no writes for 4 days" and "no writes for 10 seconds" that would allow for a distinction to be made. There could be write > in progress on the table just as it crashes Friday. > > I am aware that unlogged tables have no entries in WAL, but I assumed (incorrectly) that PG will at least keep track whether any writes was done on a table since last checkpoint, and if none, it will find no reason to truncate it. No, we don't currently track that information but it's an interesting idea, at least imv. > The use case I was thinking about is that if we have to load a large set of data every weekend and use it for reporting until next weekend, why not create those tables as unlogged. Seems like a pretty useful use-case. I had been thinking for a while, based on a comment made be someone else (Vik Fearing..), that we should have a way to turn an unlogged table into an 'init table' or similar- that is, just copy the data from the main fork into the init fork and then fsync it, then the data is there on restart. Having a way to say 'this data has been fsyncd' is a pretty interesting idea though. I wonder how hard it'd be to make that work. Thanks! Stephen
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