Robert, * Robert Haas (robertmh...@gmail.com) wrote: > On Tue, Mar 21, 2017 at 6:02 PM, David Steele <da...@pgmasters.net> wrote: > > The biggest downside I can see is that this would change the naming scheme > > for the default of 16MB compared to previous versions of Postgres. However, > > for all other wal-seg-size values changes would need to be made anyway. > > I think changing the naming convention for 16MB WAL segments, which is > still going to be what 99% of people use, is an awfully large > compatibility break for an awfully marginal benefit.
It seems extremely unlikely to me that we're going to actually see users deviate from whatever we set the default to and so I'm not sure that this is a real concern. We aren't changing what 9.6 and below's naming scheme is, just what PG10+ do, and PG10+ are going to have a different default WAL size. I realize the current patch still has the 16MB default even though a rather large portion of the early discussion appeared in favor of changing it to 64MB. Once we've done that, I don't think it makes one whit of difference what the naming scheme looks like when you're using 16MB sizes because essentially zero people are going to actually use such a setting. > We've already > created quite a few incompatibilities in this release, and I'm not > entirely eager to just keep cranking them out at top speed. That position would seem to imply that you're in favor of keeping the current default of 16MB, but that doesn't make sense given that you started this discussion advocating to make it larger. Changing your position is certainly fine, but it'd be good to be more clear if that's what you meant here or if you were just referring to the file naming scheme but you do still want to increase the default size. I'll admit that we might have a few more people using non-default sizes once we make it an initdb-option (though I'm tempted to suggest that one might be able to count them using their digits ;), but it seems very unlikely that they would do so to reduce it back down to 16MB, so I'm really not seeing the naming scheme change as a serious backwards-incompatibility change. Thanks! Stephen
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