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https://issues.apache.org/jira/browse/DDLUTILS-235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12699182#action_12699182
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Frank Jakop commented on DDLUTILS-235:
--------------------------------------
I agree with Björn, I had the same problem when running against an unchanged
MSSQL-Database.
When comparing, on the one hand the TypeCode of the column is used, on the
other hand the TypeCode is transformed by getTargetJdbcType(). In my case, the
CLOB-Type is defined in MSSqlPlatform to be mapped on LONGVARCHAR, so the
comparison of CLOB (Type 2005) with TargetJdbcType(CLOB), which is LONGVARCHAR
(Type -1) always yields false and a change is detected.
MSSqlPlatform () {
[....]
info.addNativeTypeMapping(Types.CLOB, "TEXT",
Types.LONGVARCHAR);
[....]
}
Either the mapping or the comparison have to be improved.
> Platform.alterTables detects way too many changes
> ---------------------------------------------------
>
> Key: DDLUTILS-235
> URL: https://issues.apache.org/jira/browse/DDLUTILS-235
> Project: DdlUtils
> Issue Type: Bug
> Components: Core (No specific database)
> Affects Versions: 1.0
> Reporter: Björn Schmidt
> Assignee: Thomas Dudziak
> Priority: Minor
>
> When creating an ALTER-Script from two identical databases-Models obtained
> from an unchanged HSQLDB-Database (using the same database-model also does
> the trick), all SQLBuilders of all Platforms I've tried (including the
> HSQDB-Platform) generate SQL-Output, that creates temporary tables for each
> table, copies the content of the original tables into the temporary ones,
> drops the old tables, creates everything anew and copies the data back again
> recreating all constraints like they have been before.
> That is quite a lot of work for actually not changing anything.
> I've debugged a bit and found out, that the ModelComparator detects
> column-type changes by mapping the source-model's type via the
> platformspecific typemappings to the type of the target model (which remains
> unmapped).
> if (_platformInfo.getTargetJdbcType(targetColumn.getTypeCode()) !=
> sourceColumn.getTypeCode())
> {
> changes.add(...);
> }
> This seems like a bug to me.
> Please correct me if I'm wrong, but I thought that a ddl-Database, as a
> model, does not include any specifications about the type or configuration of
> the database it has been extracted from. When comparing two databases for
> changes, the comparisions should then also be free of platform specific
> details. Those are only necessary when generating the SQL-Statements
> implementing the detected changes.
> I've patched the ModelComparator by changing the aforementioned line to
> if (targetColumn.getTypeCode() != sourceColumn.getTypeCode())
> {
> changes.add(...);
> }
> and now the Changedetection works like I would expect it to do (no changes on
> identical models, no unnecessary table- or contraint-drops).
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