Was the syntax CREATE VIRTUAL TABLE implemented with these
changes, or are they hard-wired for internal tables only now?
From: Myrna van
Lunteren [mailto:[EMAIL PROTECTED]
Sent: Saturday, November 19, 2005
2:26 AM
To: [email protected]
Subject: Re: [jira] Closed:
(DERBY-571) Virtual Table Mapping for no argument Diagnostic tables
To get this documented in the manuals, do we need an extra JIRA, or are
you already taking care of this?
On 11/18/05, Daniel
John Debrunner (JIRA) <[email protected]>
wrote:
[
http://issues.apache.org/jira/browse/DERBY-571?page=all
]
Daniel John Debrunner closed DERBY-571:
---------------------------------------
> Virtual Table Mapping for no argument Diagnostic tables
> -------------------------------------------------------
>
> Key: DERBY-571
> URL: http://issues.apache.org/jira/browse/DERBY-571
> Project: Derby
> Type: Improvement
> Components: SQL
> Reporter: Daniel John Debrunner
> Assignee: Daniel John Debrunner
> Priority: Minor
> Fix For: 10.2.0.0
>
> Currently four no-argument diagnostic tables exist that provide
information about the running state of Derby,
or its error messages.
> These tables are invoked using an awkward, non-standard syntax. As an
example:
> SELECT * FROM NEW org.apache.derby.diag.LockTable() as LOCK_TABLE
> The improvement will provide an internal mapping from a regular table name
in the SYSCS_DIAG schema
> to the runtime virtual table code. Thus the above example would be
replaced by:
> SELECT * FROM SYSCS_DIAG.LOCK_TABLE
> These diagnostic table expressions are regular table expressions (as is
the NEW VTI construct) and
> can be used wherever a normal table can.
> Any DDL, INSERT/UPDATE/DELETE, compression procedure etc. that references
a diagnostic table
> will result in an exception.
> The old style syntax will remain in place for 10.2, but become deprecated.
> The tables to be implemented in this change are:
> SYSCS_DIAG.LOCK_TABLE replaces org.apache.derby.diag.LockTable
> SYSCS_DIAG.STATEMENT_CACHE replaces org.apache.derby.diag.StatementCache
> SYSCS_DIAG.TRANSACTION_TABLE replaces
org.apache.derby.diag.TransactionTable
> SYSCS_DIAG.ERROR_MESSAGES replaces
org.apache.derby.diag.ErrorMessages
> Adding such a table will be table driven, thus easy for others to provide
additional diagnostics.
> Information about these diagnostic tables will not appear in the system
catalogs or JDBC DatabaseMetaData.
> The ResultSetMetaData for the any query involving a diagnostic table will
be valid.
> This is a first step in a progression towards supporing a fully
application/user defined virtual table.
> These steps are not part of this jira issue, but added for information
purposes.
> - second step - supporting diagnostic tables with parameters, e.g.
> SELECT * FROM SYSCS_DIAG.SPACE_TABLE('sales', 'orders');
> - third step - providing a create virtual table statement (most databases
support
> some form of virtual table, or wrappers). The DDL
would be non-standard but the
> data access would be standard. [need to check table
functions in part 13 of SQL standard]
> E.g. syntax yet to be defined, but to give the
general idea
> CREATE VIRTUAL TABLE (TICKER
VARCHAR(10), START TIMESTAMP, END TIMESTAMP)
> LANGUAGE
JAVA
> PARAMETER
STYLE JAVA
> EXTERNAL
NAME 'com.acme.stocks.historyFromYahooFinance';
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