* Joshua D. Drake (j...@commandprompt.com) wrote: > > 2. What do you think such a feature should look like? > > I liked the other post that said: EXPLAIN <ALTER TABLE> or whatever. > Heck it could even be useful to have EXPLAIN ANALZYE <ALTER TABLE> > in case people want to run it on staging/test/dev environments to > judge impact.
The downside of the 'explain' approach is that the script then has to be modified to put 'explain' in front of everything and then you have to go through each statement and consider it. Having a 'dry-run' transaction type which then produces a report at the end feels like it'd be both easier to assess the overall implications, and less error-prone as you don't have to prefex every statement with 'explain'. It might even be possible to have the local "view" of post-alter statements be available inside of this 'dry-run' option- that is, if you add a column in the transaction then the column exists to the following commands, so it doesn't just error out. Having 'explain <whatever>' wouldn't give you that and so you really wouldn't be able to have whole scripts run by just pre-pending each command with 'explain'. > > 3. Does it make sense to support the whole set of DDL commands from the > > get go (or ever) when most of them are only taking locks in their > > own pg_catalog entry anyway? > > I would think that introducing this incrementally makes sense. Agreed. Thanks, Stephen
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