On Sat, Feb 23, 2019, 21:30 Vlad Khorsun <hv...@optima.com.ua> wrote:
> 23.02.2019 21:14, Adriano dos Santos Fernandes wrote: > > Hi! > > > > After changes to use commit number instead of base transaction number, I > > offer to make that interfaces for the feature: > > I offer to not introduce additional confusing with different usages of > commit > numbers. > > Commit Number (CN) itself is an unique value assigned to the every > committed > transaction. The source of that value is per-database counter. When some > database > snapshot is created it uses current value of database counter of commit > numbers > as own identifier. Lets name it Snapshot Number (SN) to distinguish from > Commit > Number assigned to transaction. The sourse of CN and SN is the same, but > usage > and meaning is very different ! > > Therefore > > > SQL command: SET TRANSACTION SNAPSHOT COMMIT NUMBER <cn> > > > > (some variant as SNAPSHOT FROM COMMIT NUMBER or SNAPSHOT BASE COMMIT > > NUMBER may be acceptable) > > maybe: > SET TRANSACTION SNAPSHOT [USING SNAPSHOT <N>] > or > SET TRANSACTION SNAPSHOT [USING SNAPSHOT NUMBER <N>] > What I dislike here is double SNAPSHOT words. > > > > TPB: isc_tpb_snapshot_commit_number, <commit number length> <commit > number> > > isc_tpb_snapshot_number <len> <value> > > Regards, > Vlad > > PS we also must add isc_info_tra_snapshot_number and, probably, context > variable. > Don't we already have context SNAPSHOT_CN? It already has the same meaning of the new feature, so therefore what context you would want to add? And then SNAPSHOT_CN means "SNAPSHOT COMMIT NUMBER", it's the reason for the syntax that I offered. Adriano
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