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I've been trying to get information on a programming interface to the database. Over
the last while Dave Page and I have emailed each other. Dave has suggested I join the
hacker maillist.
Thus I am forwarding the communication I sent to Dave. I hope this is approriated in
this channel. If not please advise where I should go.
I'll look forward to some clarification about what is or is not available by way of
talking to the database from languages like C.
Thanks.
Terrell Larson
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Date: Fri, 7 Mar 2003 04:18:45 -0700
From: terr
To: Dave Page <[EMAIL PROTECTED]>
Subject: Re: Fwd: ODBC docs
Message-ID: <[EMAIL PROTECTED]>
References: <[EMAIL PROTECTED]>
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In-Reply-To: <[EMAIL PROTECTED]>; from [EMAIL PROTECTED] on Fri, Mar 07, 2003 at
08:49:00AM -0000
Over at M$, I see the following:
* SQQLAllocConnect Function
* SQLAllocEnv Function
* SQLAllocHandle Function
* SQLAllocStmt Function
* SQLBindCol Function
* SQLBindParameter Function
* SQLBrowseConnect Function
* SQLBulkOperations Function
* SQLCancel Function
* SQLCloseCursor Function
* SQLColAttribute Function
* SQLColAttributes Function
* SQLColumnPrivileges Function
* SQLColumns Function
* SQLConnect Function
* SQLCopyDesc Function
* SQLDataSources Function
* SQLDescribeCol Function
* SQLDescribeParam Function
* SQLDisconnect Function
* SQLDriverConnect Function
* SQLDrivers Function
* SQLEndTran Function
* SQLError Function
* SQLExecDirect Function
* SQLExecute Function
* SQLExtendedFetch Function
* SQLFetch Function
* SQLFetchScroll Function
* SQLForeignKeys Function
* SQLFreeConnect Function
* SQLFreeEnv Function
* SQLFreeHandle Function
* SQLFreeStmt Function
* SQLGetConnectAttr Function
* SQLGetConnectOption Function
* SQLGetCursorName Function
* SQLGetData Function
* SQLGetDescField Function
* SQLGetDescRec Function
* SQLGetDiagField Function
* SQLGetDiagRec Function
* SQLGetEnvAttr Function
* SQLGetFunctions Function
* SQLGetInfo Function
* SQLGetStmtAttr Function
* SQLGetStmtOption Function
* SQLGetTypeInfo Function
* SQLMoreResults Function
* SQLNativeSql Function
* SQLNumParams Function
* SQLNumResultCols Function
* SQLParamData Function
* SQLParamOptions Function
* SQLPrepare Function
* SQLPrimaryKeys Function
* SQLProcedureColumns Function
* SQLProcedures Function
* SQLPutData Function
* SQLRowCount Function
* SQLSetConnectAttr Function
* SQLSetConnectOption Function
* SQLSetCursorName Function
* SQLSetDescField Function
* SQLSetDescRec Function
* SQLSetEnvAttr Function
* SQLSetParam Function
* SQLSetPos Function
* SQLSetScrollOptions Function
* SQLSetStmtAttr Function
* SQLSetStmtOption Function
* SQLSpecialColumns Function
* SQLStatistics Function
* SQLTablePrivileges Function
* SQLTables Function
* SQLTransact Function
This looks like the API. Thanks. Now - IMHO "we" should have these docs on "our"
website instead of having to rely on M$.
It this is truely not currently available I may be able to start flanging something
up. I suspect that there may be bits and peices around... perhaps the whole thing.
Also - I really want to find out how some of these functions are implemented. The
problem I'm looking at is that:
(1) if I use ecpg then I get over 1000 parameters stuffed into some of the calls.
This is just plain NUTZ. Aside from it being virtually insane to try to pass this
many parameters to a function call, it makes absolutly no sense to stack over 1000
addresses, call the interface, find out the row is not present, tear down the
addresses, build the row (about 100 fields), stack over 1000 addresses bak up, call
the interface to post the row, and tear the stack back down only to do this all over
again for the next row.
Passing this many addresses is so NUTZ that when I popped into the #C developers group
on Freenode and also the #debian channels and asked if anyone knew the maximum number
of parameters one could pass into a function call - that they started to abuse me!
haha. Some must have thought I was a 1st year uni student without much common sense.
What can I say. IMHO 1000+ parameters is an embarrasment.
(2) if I use libpg then I apparently have to map each and every column for each row
over and over, column by column for each row in a manner that is very similar to (1).
None of the columns change between calls to the database and none of the variables
move around. (in this case the buffers are statically mapped - by design) I should be
able to build up a table of the mapping of MY C VARIABLES into the columns in the
table ONCE at the beginning of a run and then use it over and over row by row as I
post things into the database.
(3) The update functions I have encountered so far are basically a SQL INSERT
statement. This means that my code must go through the buffer containing the row to
be inserted and build up a HUGE string with ugly codes in it - converting binary
values into ACSII and eventually having done this HUGE amount of work, pass the string
to the interface so that it can parse the string which is a HUGE amount of work and
eventually get the data back into a mapped binary buffer from which the database
manager can arrange to store it in the database on disk.
To put it bluntly this sort of interface is INSANE.
What I need is the following structure passed into the database manager:
struct record_mapping {
void *address_of_field; // a pointer to the data
enum field_type; // as defined: pgint, pgfloat, pgvarchar, pgblob...
char *field_name; // internal name in the database
etc
etc
etc
}
and then I can call an initialization routine passing either this structure or the
information in it to the database manager in say a cursor.
If this interface does NOT exist then it should be created.
If I were to do this then I would create the following functions:
pg_cursor_address = pg_Create_Cursor ( db_handle, max_number_variables );
if the address is NULL then the function failed. the error code should be in
db_handle. If we can't put it into the handle, then we pass &success, an int.
int success = pg_Define_Column_Entry ( pg_cursor_address, &myvar, pg_field_type,
"column-name", .... );
If it is successful, sucess = 0, if fails, sucess has the error code.
pg_cursor_address = pg_Destroy_Cursor ( pg_cursor_address );
This routine returns a NULL thus detroying the pointer. Meanwhile any malloc()'s are
freed and the cursor is torn down.
success = pg_Exec_Query ( pg_cursor_address, "insert");
an example of how to insert a row. success = 0 => ok. non-zero carries an extensive
list of reasons. The text of the reason should be retrivable with a sister function.
success = pg_Exec_Query ( pg_cursor_address, "select where blah" );
an example of how to fetch a row. Only the first selected row is copied into the
transfer buffer. Again success = 0 implies you got the data.
success = pg_Exec_Query ( pg_cursor_address, "next-row" );
When the last row has been returned, a success is set to a non-zero.
success = pg_Exec_Query ( pg_cursor_address, "replace-row" );
In this case, the application fetched the row, updated it and wants the replacement
posted into the database.
------------
I'll stop now. I just fired this off the top of my head. I'm looking to find an
interface that will sort of work like this, and work relatively efficiently. Perhaps
this is the ODBC interface and perhaps it is the libpg interface... but if this is in
libpg I sure could not find it.
IF this interface does NOT exist then I could perhaps write it. Now, I am not
familiar with the source tree or what internal functions and structures might be
available to support this. Clearly I could write an interface like this and hook it
up to libpg - but the libpg from what I can tell does NOT support a cursor and needs
to build up a call column by column and this is what we're trying to avoid.
Given the excellent quality of PostgreSQL I just *HAVE* to believe a suitable
interface already exists and I have just not been able to find it.
Again, if it does not exist, with a very small amount of guidence I figure I can
probably make it happen. If this is the direction we need to go, then I would like
the opportunity to knock heads with some people who are already familiar with what is
out there so as to define exactly HOW this interface should look so that it comes out
looking clean and well thought out and not some botch created by an amature.
Thanks for your help.
On Fri, Mar 07, 2003 at 08:49:00AM -0000, Dave Page wrote:
> Why not take a look at msdn.microsoft.com? There is some very useful
> documentation in the Data Access SDK on ODBC - and after all, Microsoft
> did invent it!
>
> Regards, Dave.
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > Sent: 07 March 2003 09:43
> > To: Dave Page
> > Subject: Re: Fwd: ODBC docs
> >
> >
> > I've been through that documentation. THere is some docs on
> > using the odbc interfce from JODBC and from Python, but there
> > is nothing on how to use it from C or C++.
> >
> > In my case, I was planning on doing the database interface in
> > C, bit C++
> >
> >
> > On Fri, Mar 07, 2003 at 08:03:23AM -0000, Dave Page wrote:
> > > Should be OK now. The server had a RAID controller failure.
> > >
> > > Regards, Dave.
> > >
> > > > -----Original Message-----
> > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > > > Sent: 07 March 2003 00:45
> > > > To: Dave Page
> > > > Subject: Re: Fwd: ODBC docs
> > > >
> > > >
> > > > This link takes me to here:
> > > > http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
> > > >
> > > > there is a link there which says "PostgreSQL Docs" the link
> > > > does not work and I get this:
> > > >
> > > > Warning: pg_exec(): supplied argument is not a valid
> > > > PostgreSQL link resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 184
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 187
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 190
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 191
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 192
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 193
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 194
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 195
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 196
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 197
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 198
> > > >
> > > > Warning: pg_result(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/globals.php on line 205
> > > >
> > > > Warning: pg_exec(): supplied argument is not a valid
> > > > PostgreSQL link resource in
> > > > /usr/local/www/www.postgresql.org/docs/view.php on line 23
> > > >
> > > > Warning: pg_numrows(): supplied argument is not a valid
> > > > PostgreSQL result resource in
> > > > /usr/local/www/www.postgresql.org/docs/view.php on line 25
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On Fri, Mar 07, 2003 at 12:19:23AM -0000, Dave Page wrote:
> > > > > It's rumoured that Bruce Momjian once said:
> > > > > >
> > > > > > You can find stuff at odbc.postgresql.org, I think.
> > > > > >
> > > > > >
> > > > >
> > > > > Hi Bruce,
> > > > >
> > > > > That's now deprecated. It's all at
> > > > > http://gborg.postgresql.org/project/psqlodbc/ now.
> > Regards, Dave.
> > > > >
> > > > >
> > > >
> >
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