Re: [MonetDB-users] mapi and xquery

2 Jul 2005

      XQuery works a bit different:
on the first line you send the options,
then after that the query follows.
An example of JdbcClient using it:
% JdbcClient -lxquery -p45789 -Xdebug
Connection warning: database specifier not supported on this server 
(mserver_xquery), protocol version 4
Welcome to the MonetDB interactive JDBC terminal!
Type \q to quit, \h for a list of available commands
auto commit mode: on
monetdb-> 1 + <foo>1</foo>;
+--------------------------------------------------------------+
| xml                                                          |
+==============================================================+
| 2.000000                                                     |
+--------------------------------------------------------------+
1 row
monetdb->
% cat monet_1120328168519.log
RX 1120328168521: 19
RX 1120328168521: ::mserver_xquery:4
TX 1120328168522: monetdb:monetdb:xquery:blocked
TX 1120328168522: �
RX 1120328168523: �
RX 1120328168523: new block: 3 bytes
RX 1120328168563: read chunk: 3 bytes, left: 0 bytes
RX 1120328168564:
TX 1120328171821: write block: 29 bytes
TX 1120328171821: xml-seq-mapi
1 + <foo>1</foo>
TX 1120328171822: zero block (flush)
RX 1120328171822: zero block (flush)
RX 1120328171914: new block: 151 bytes
RX 1120328171914: read chunk: 151 bytes, left: 0 bytes
RX 1120328171914: #-
# 3     # querytype
# xquery_result,        xquery_result   # table_name
# xml   # name
# varchar       # type
# 60    # length
# 1     # tuplecount
# 1     # id
[ "2.000000"    ]
The important aspect for you here is the part:
TX 1120328171821: xml-seq-mapi
1 + <foo>1</foo>
the newline is what separates the options from the actual query.  You 
probably want to use another query mode though, because xml-seq-mapi 
generates the headers and tuple format, so the JDBC driver can deal with it.
Martijn Faassen wrote:
...
Hi there,
I'm trying to figure out how to use mapi to do an xquery. I have been 
able to shred documents (using MIL), but mapi with xquery is giving me 
trouble.
Looking at the implementation of MapiClient, I see the following piece 
of code which appears relevant:
            /* xquery options are passed via the command string
               (becomes first line of query) */
            char *c = command ? command : XQuerydefaultMode;
            char *t = strstr(c, "timing-") ? "" : mark ? "timing-" : 

"";
                char *d = strstr(c, "debug-") ? "" : trace ? "debug-" : "";
                char *m = strstr(c, "-mapi") ? "" : "-mapi";
            command = (char*) malloc(strlen(c) + 20);
            sprintf(command, "%s%s%s%s\n", t, d, c, m);

as well as this code:
    if (command) {
            /* special code for XQuery: prepend command to query */
            hdl = mapi_query_prep(mid);
            CHECK_RESULT(mid, hdl, buf, break);
            mapi_query_part(hdl, command, strlen(command));

what exactly is going on here? The logic is rather opaque... Is there 
some minimal code example somewhere out there that shows how to do an 
xquery using mapi?
Regards,
Martijn

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Re: [MonetDB-users] mapi and xquery

Fabian