Outline transactions idea

[svenseeberg]

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[svenseeberg]

Discussion results:

• The problem with the current DB mutex is that read operations that precede the write operations can contain outdated information due to race conditions. We would have to include SELECT FOR UPDATE in the transactions.
• Currently there are no transactions and therefore no (deferrable) constraints
• We could replace the raw queries with ORM calls, do performance tests, and compare both implementations. This would enable us to implement deferrable constraints and transactions which would guarantee a consistent table after the transaction is complete.
• We can add BEGIN and COMMIT statements only to the raw queries. That would also allow to add deferrable constraints. The transaction would then not span multiple queries (for example object saves) but most likely cover most of the occurring problems. Works in Add deferrable Page tree constraints integreat-cms#2596
• Another option would be to connect treebeard to the Django ORM so that Treebeard operations are somehow connected to atomic ORM operations.
• We should add a single root node for each region to avoid constantly changing tree IDs.