On 4/13/15 6:21 AM, Anil Menon wrote:
In addition to all these comments - If you use multiple databases, if you want to keep some "common" tables (example counties_Table, My_company_details), its going to be a pain - if you want to access tables across databases - you might need to start using FDWs (which is going to be a administrative pain - syncing passwords and stuff) - you could set up security easier with multiple schemas - example userA can only use schema A and no access to other schemas
Please don't top-post.
On Mon, Apr 13, 2015 at 4:48 PM, Pavel Stehule <pavel.stehule@xxxxxxxxx <mailto:pavel.stehule@xxxxxxxxx>> wrote: 2015-04-13 10:43 GMT+02:00 Albe Laurenz <laurenz.albe@xxxxxxxxxx <mailto:laurenz.albe@xxxxxxxxxx>>: Michael Cheung wrote: > I have many similar database to store data for every customer. > Structure of database is almost the same. > As I use same application to control all these data, so I can only use > one database user to connect to these database. > And I have no needs to query table for different customer together. > > I wonder which I should use, different shema or different database to store data? > > I 'd like to know the advantage and disadvantage for using schema or database. In addition to what others have said: If you use multiple schemas within one database, the danger is greater that data are written to or read from the wrong schema if your application has a bug ans does not make sure to always set search_path or qualify every access with a schema name. With multiple databases you are guaranteed not to access data from a different database. The main downside that I see to multiple databases is the overhead: each of the databases will have its own pg_catalog tables. It can be advantage - if your schema is pretty complex - thousands procedures, tables, then separate pg_catalog can be better - there are issues with pg_dump, pg_restore. So it depends on catalog size and complexity.
Two things no one has mentioned. First, you could also use row-level security. If you plan on each customer having a fairly small amount of data, this is by far your most efficient option. Anything else will result in either huge catalogs or a lot of wasted catalog space.
Second, if you do per-database, that makes it trivial to scale across multiple servers.
Regarding backups; you can easily do partial either way with pg_dump; there's really no difference. You can't do partial with PITR, but that's true for both schema and database.
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