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Date: Sat, 13 Oct 2012 18:10:03 +0000 (UTC)
From: "Dag H. Wanvik (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Message-ID: <1368159317.41825.1350151803358.JavaMail.jiratomcat@arcas>
Subject: [jira] [Closed] (DERBY-3652) Derby does not follow the SQL Standard
 when trying to map SQL routines to Java methods.
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     [ https://issues.apache.org/jira/browse/DERBY-3652?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dag H. Wanvik closed DERBY-3652.
--------------------------------

    
> Derby does not follow the SQL Standard when trying to map SQL routines to Java methods.
> ---------------------------------------------------------------------------------------
>
>                 Key: DERBY-3652
>                 URL: https://issues.apache.org/jira/browse/DERBY-3652
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.5.1.1
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>             Fix For: 10.5.1.1
>
>         Attachments: badsignatures.sql, derby-3652-01-aa-mixTypesOnFirstPass.diff, derby-3652-01-ab-mixTypesOnFirstPass.diff, derby-3652-01-ac-mixTypesOnFirstPass.diff, derby-3652-01-ad-mixTypesOnFirstPass.diff, derby-3652-02-aa-dontWidenExceptForSmalllint.diff, derby-3652-02-ab-dontWidenExceptForSmalllint.diff, derby-3652-03-aa-dontWidenSmallint.diff, derby-3652-03-ab-dontWidenSmallint.diff, derby-3652-04-aa-deprecateJavaRules.diff, derby-3652-05-aa-moreTests.diff, derby-3652-06-aa-dontWidenString.diff, derby-3652-07-aa-dontWidenBigDecimal.diff, derby-3652-08-aa-dontWidenAtAll.diff, derby-3652-09-aa-mixedTypes.diff, derby-3652-10-aa-SignatureChecker.diff, derby-3652-11-aa-binaryTests.diff, derby-3652-12-aa-charAndLongvarchar.diff, derby-3652-13-aa-decimalDateTimeTimestamp.diff, derby-3652-14-aa-blobClobTests.diff, derby-3652-badmatches.diff, releaseNote.html, SignatureMapping.html, SignatureMapping.html, SignatureMapping.html, SignatureProblems.java, signatureProblems.sql
>
>
> I have only tested this in the 10.5 trunk. However, I suspect that this affects all previous releases of Derby as well.
> In resolving method signatures for function/procedure invocations, the SQL standard makes the following definitions in part 13, section 4.5 (parameter mapping). These definitions, in turn, refer to tables B-1 and B-3 in JDBC 3.0 Specification, Final Release, October 2001 ([JDBC]).
>     * Simply mappable - This refers to the correspondence of SQL and Java types described in [JDBC] table B-1. This is the table which defines the mapping of SQL types to Java primitives.
>     * Object mappable - This refers to the correspondence of SQL and Java types described in [JDBC] table B-3. This is the table which defines the mapping of SQL types to Java wrapper objects.
>     * Output mappable - For OUT and INOUT parameters, this refers to a single element array whose cell is simply mappable or object mappable. E.g. Integer[] or float[].
>     * Mappable - This means simply, object, or output mappable.
>     * Result set mappable - This means a single element array whose cell is a type which implements either java.sql.ResultSet or sqlj.runtime.ResultSetIterator.
> Putting all of this together, section 4.5 continues:
>     "A Java method with M parameters is mappable (to SQL) if and only if, for some N, 0 (zero) <= N <= M, the data types of the first N parameters are mappable, the last M - N parameters are result set mappable, and the result type is either simply mappable, object mappable, or void."
> Section 8.6 gives more detailed rules, but they are hard to follow. According to section 8.6, when resolving a routine invocation, Derby should expect to find one and only one static mappable method with the expected external name (Java class + method name).
> I believe that this is a fair description of the rules. This, at least, is what some other databases appear to do. See, for instance, http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.ase_15.0.java/html/java/java126.htm and http://www.service-architecture.com/database/articles/mapping_sql_and_java_data_types.html
> We do not have a regression test which verifies that Derby applies the SQL standard resolution rules. There may be several divergences from the standard. This JIRA is a place to track those discrepancies. Here is one that I have noticed:
> The following SQL signature
> ( a int ) returns int
> should be mappable to any of the following Java signatures
> public static int f( int a )
> public static int f( Integer a )
> public static Integer f( int a )
> public static Integer f( Integer a )
> However, I observe that Derby is only able to resolve the first and third signatures (the ones with primitive arguments). I will attach a test case showing this problem.
> I will also attach an html table summarizing the simply and object mappable rules.

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