Hi Thomas, Yes both those reasons: the database (table) is large, and so users have little perceived delay for their queries to run.
Why does the database always need to be available (why is there a desire to avoid maintenance windows)? Because it is a web based application and users are accustomed to little or no downtime (DDL is fast in pg and my). For example if one has a table storing GIS coordinates (millions of records) and wants to add a column to store 'elevation' (in advance of deploying code that would use that new column). 'waiting until the column is added' can be many minutes for tables of multiple gigabytes, and this blocking might consume all connection-pool cons (or server- threads/connector as the case may be), causing outages for apps that use the same database connection even if they aren't querying the being-altered table.. one then needs to add code to the webapp that rejects query to whatever table is being altered... this hasn't been necessary with pg or my. If h2 can run DDL operations fast it will be one less thing for everyone to worry about/explain. Best regards, ken On Jun 23, 11:58 am, Thomas Mueller <[email protected]> wrote: > Hi, > > You have more or less described the feature, but I would like to > understand *why* you need the feature. Why can't you just wait until > column is added? Because you have a large database, or because the > database needs to be always usable (if so, why),... Is there no > "maintenance window", and if so, why not? > > Regards, > Thomas -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/h2-database?hl=en.
