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0 pointsaeyes5y ago0 comments

In theory this is much better than what Postgres currently does. Performance depends on autovacuum cleaning up the mess you leave behind, with the amount of dead tuples increasing you also get index bloat which leads to reading much much more data than necessary. I see 3-5x read amplification before vacuum kicks in on update heavy tables (with vacuum tuned a lot).

This is basically what Oracle does with UNDO and it is obviously very scalable. Vacuum on the other hand has its limits, there is only so much you can squeeze out of a single threaded (at table level) process.

What I look most forward to is that it should enable FLASHBACK queries.

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jeltz5y ago

I doubt that because in practice PostgreSQL is faster on many workloads than Oracle and InnoDB despite Oracle and InnoDB using similar models to zheap. If the theoretical difference has been large then we should also expect to see big differences in practice, which is not the case.

While zheap may be a superior design I do not think you should expect any major performance improvements other than on some very specific workloads.

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0 pointsaeyes5y ago0 comments

What I look most forward to is that it should enable FLASHBACK queries.

0 comments

jeltz5y ago

While zheap may be a superior design I do not think you should expect any major performance improvements other than on some very specific workloads.

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