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DDC-2719: [GH-810] New versioning strategy for optimistic lock: next version value managed by App #3461

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doctrinebot opened this Issue · 3 comments

2 participants

@doctrinebot

Jira issue originally created by user @doctrinebot:

This issue is created automatically through a Github pull request on behalf of diego-mazzaro:

Url: #810

Message:

With this improvment the next value for the version field used for the optimisic lock strategy can be managed by the application.

When can be useful?
Obviously it is useful if we whant different values than the standard and for example:

  • using also negative numbers
  • using a combination of datetime and progressive number
  • mark with the same version all the records touched in a single updating session
  • anything that I want to do with my app and can be meaningful for me

And really can be done something different from standard ways?
The base property that a version column next value must have in order to accomplish his own task is this:
be different from any value that any other concurrently running client/process/thread/session may have read as current version value for the same record.
The opposite may sound more clear: if I write the same value that anyone concurrently working with me has read as current version he will find the same version when writing and will think that all is ok.

That told the standard implementations are:

  • next version = version + 1: prerfect
  • next version = TIMESTAMP: not so perfect but someone can live with

This two obviously respects the base property but the point is that they are not the only ones. Some examples:

  • increment by two: not so strange but different
  • increment up to 1000 and then restart from 0
    • if I'm sure that every session will end before other 1000 session has occourred it can work
  • use a GUID as version so I will "never" finish the possible values
  • use strings
    • wisely: knowing the "base property"
  • use values from an autogenerated ID of other table (generated for each updating session)
@doctrinebot

Comment created by diego.mazzaro:

I forgot to give an example of how configuration files has to be written to let this additional versioning mode works.
Here is following with an yml mapping file:

```none type: entity
id:
id:
type: integer
nullable: false
fields:
code:
type: string
length: 20
nullable: false
description:
type: string
length: 40
nullable: false
[... other data fields ...]
versionField:
type: integer
nullable: false
version:
nextVersionProperty: currentTid # <<= this is the key row to have it working
[... mappings and other ...]


pratically all remains as usual but if under the "version" label a sub label "nextVersionProperty" is found then the class property with that name will be added to the `reflFields` so that its value can be used when preparing the INSERT and UPDATE of the `versionField`.
@doctrinebot

Comment created by @doctrinebot:

A related Github Pull-Request [GH-810] was closed:
#810

@doctrinebot

Issue was closed with resolution "Won't Fix"

@beberlei beberlei was assigned by doctrinebot
@doctrinebot doctrinebot closed this
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