Dennis, your application may not be a microwave oven but it does appear
to be "deeply embedded" as opposed to a general purpose DB server which
handles generic queries.
I was aware of the runtime only version of Sqlite, but is it not
directly comparable to DeviceSQL unless the external compiler handles
not only SQL but also PL/SQL. The addition of the command language
allows for creating a library of data manipulation functions rather than
just embedded SQL. My point was that the DeviceSQL approach could be
used with Sqlite to produce a smaller footprint embedded product and
that such a product has the potential of being less memory hungry than
DeviceSQL simply by virtue of the higher information density of the VDBE
target code compared to native machine instructions.
Dennis Cote wrote:
John Stanton wrote:
DeviceSQL is not suitable for general purpose SQL processing, unlike
Sqlite, and should only be compared as an alternative in deeply
embedded applications so the only useful comparison is one which looks
like a cell phone, microwave oven or a TV set top box.
The application doesn't necessarily have to look like a microwave. :-)
It could be any application that uses a fixed set of predetermined SQL
statements to perform its operations. My primary application does
exactly that using SQLite with all statements prepared and cached as
needed. It runs on a standard PC under Windows. We have no need for
executing arbitrary, runtime generated, or user supplied SQL as many
other applications do. Every SQL statement that can be executed is known
before the application starts.
I can imagine that a version of Sqlite which does not include its SQL
compiler and which uses precompiled VDBE code would provide similar
functionality to DeviceSQL, particularly if the Sqlite compiler were
extended to generate VDBE from PL/SQl. I can imagine that the higher
information density of the VDBE code could deliver the advantage =of a
smaller memory footprint.
I thought that this already existed as a commercial product that Richard
offered, but I can't find any reference to it on the paid support page
at http://www.hwaci.com/sw/sqlite/prosupport.html. My recollection was
an offline compiler that ran on a PC and generated VDBE code to execute
SQL statements, along with source code for a runtime execution engine
that would execute those pre-compiled statements. The execution engine
could be built for any target, and was much smaller than SQLite because
it eliminated the parser and code generator functionality. Does this
exist, or was I just imagining it?
Dennis Cote
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