Could we get the long and the short of it please?

What SQL objects can we safely create and or modify by simply using DML
statements against the system tables?

There are system triggers that don't have the source code included, is
it possible for that source (as it is more of macro format vs C source)
to be released before the rest of the Interbase code?

Is there a simple reference guide to BLR (maybe the bnf or ebnf of the
blr parser?)

I know I am asking alot, but, this would give us a far better
understanding of how IB operates in preparation for the source code.

best regards

Dalton


Charlie Caro wrote:

>
> Jim Starkey wrote:
> >
> > DDL is a different story. The real DDL operations are performed
> > by ordinary DML to the system tables. SQL DDL is what is known
> > in the biz as syntactic sugar.
> >
>
> The DSQL component emits BLR for DML statements and something
> called DYN (dynamic DDL) for DDL statements. DYN is yet another
> byte encoded language for describing data definition statements.
>
> Jim created the DYN language when our VARs were demanding a way
> to upgrade their customers databases in the field. The customers'
> databases were licensed for run-time operation only. The high-level
> tool, GDEF, which performed DDL operations was unlicensed. So, Jim
> created a low-level, byte-encoded language which GDEF generated
> from a high-level, GDEF script. The VARs could then distribute the
> machine-generated DYN to their clients to modify the underlying
> metadata. I guess you could call DYN an obfuscated, back door for
> metadata operations.
>
> Today, the same server-side DSQL parser generates parse trees for
> both SQL DML and DDL statements. The DDL parse trees are passed
> to a component which emits DYN. That DYN is immediately passed to
> the Y-valve entrypoint ISC_DDL which interprets the DYN and performs
> the actions on the system tables.
>
> So the behavior is as Jim describes but the path is a bit more
> circuitous than one would expect.
>
> Regards,
> Charlie
>
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