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From "Thomas Dudziak (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DDLUTILS-214) Primary Key Column order lost (a problem if there are multiple Primary Keys)
Date Fri, 01 Aug 2008 05:28:31 GMT

     [ https://issues.apache.org/jira/browse/DDLUTILS-214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Thomas Dudziak updated DDLUTILS-214:
------------------------------------

    Affects Version/s:     (was: 1.0)
                       1.1
        Fix Version/s:     (was: 1.0)
                       1.1

> Primary Key Column order lost (a problem if there are multiple Primary Keys)
> ----------------------------------------------------------------------------
>
>                 Key: DDLUTILS-214
>                 URL: https://issues.apache.org/jira/browse/DDLUTILS-214
>             Project: DdlUtils
>          Issue Type: Bug
>          Components: Core (No specific database)
>    Affects Versions: 1.1
>         Environment: Any
>            Reporter: Rijk van Haaften
>            Assignee: Thomas Dudziak
>            Priority: Critical
>             Fix For: 1.1
>
>
> Symptom:
> 14558 [btpool0-5] DEBUG org.apache.ddlutils.platform.postgresql.PostgreSqlPlatform  -
About to execute SQL DELETE FROM "a" WHERE "p" = ? AND "q" = ?
> The delete sometimes works, sometimes I get this:
> 14569 [btpool0-5] WARN  org.apache.ddlutils.platform.postgresql.PostgreSqlPlatform  -
Attempted to delete a single row "a": q = 6, p = 3 in table "a" but changed 0 row(s).
> Symptom analysis:
> The query
> DELETE FROM "a" WHERE "p" = ? AND "q" = ?
> is filled in order (6,3), without regarding the field names (q = 6, p = 3) resulting
in
> DELETE FROM "a" WHERE "p" = 6 AND "q" = 3
> Code analysis
> 1. SqlBuilder.getDeleteSql
> SqlBuilder.getDeleteSql uses the Map pkValues iterator to generate the prepared statement.
> 2. PlatformImplBase.toColumknValues
> This has a major problem: Map iterator order is not defined. Java documentation: "Some
map implementations, like the TreeMap class, make specific guarantees as to their order; others,
like the HashMap class, do not." In this case, the Map used is created by PlatformImplBase.toColumknValues:
>     protected HashMap toColumnValues(SqlDynaProperty[] properties, DynaBean bean) {
>         HashMap result = new HashMap();
>         ...
>     }
> so iterator order is undefined.
> 3. PlatformImplBase.delete (for example)
> a)
>             String sql = createDeleteSql(model, dynaClass, primaryKeys, null);
> createDeleteSql uses getDeleteSql (1) and due to (2), the order the columns in the generated
String sql is undefined. So, this could generate either
>  DELETE FROM "a" WHERE "p" = ? AND "q" = ?
>  DELETE FROM "a" WHERE "q" = ? AND "p" = ?
> which one cannot be determined
> b) setObject uses a deterministic array order sqlIndex to fill the ? - marks
>             SqlDynaProperty[] primaryKeys = dynaClass.getPrimaryKeyProperties();
>             for (int idx = 0; idx < primaryKeys.length; idx++)
>             {
>                 setObject(statement, idx + 1, dynaBean, primaryKeys[idx]);
>             }
> so there is a chance of 1/(number of PK columns) this will run correctly.
> Solution:
> use LinkedHashMap or TreeMap: they retain put-order, which is based on the SqlDynaProperty[]
so by definition has the same order as the setObject loop:
>     protected HashMap toColumnValues(SqlDynaProperty[] properties, DynaBean bean)
>     {
>         HashMap result = new LinkedHashMap();
>         ...
>     }

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