Platform.alterTables detects way too many changes
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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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